+mark teague no problem, i have started to go through a carb series where im going to explain all my basic holley carb tuning points. you can find it on my channel under recent uploads. im doing a jet video today.
good afternoon friend I write from of Venezuela my name is jesus I have a holley 600cfm carburetor and I have a problem I smoked spark plugs and it gives me a lot of power failure have to remove and clean all the spark plugs every day that produces much carbon my question is this which should give the carburetor that can regulate and where that nadien not get to help me to regulate the amount of fuel Injection as safe as that would be the cause of the problem and you correct me if I equivoco I thank you very much for the help you can give me this is my mail dj : caiman@gmail.com
@@ThunderHead289 so is a Holley power valve the same thing basically as a accelerator pump on a 2V? I am trying to solve a issue on my stock 351M 2V thats in a 77 f150. It idles great but starts breaking up around 2500 rpms, even worse under load. Ignition timing set at 10° So far I have replaced plugs, rotor & button, ignition coil & connector, voltage regulator, alternator and battery. Looked under the hood at night and there's no spark jump from wires at all.
the quality of sound reminds me of the old high school reel movies that you never watched since you were too busy thinking of the dynamite chick sittin a few tables away from ya
I run 58 primary jets and 72 secondary with a block off plate on my 850 dp,so it's actually a lot more like 10-14 sizes higher for your secondaries.thank you I enjoyed the video very much..
850? I wouldn`t think an 850 would run that lean. 80 and 86, with back power valve plugged, would be a starting point. Hell, even a 650 would use 67`s.
Good video but behind the power valve are the two pvcr ( power valve channel restricters) the emulsion bleeds are on the the vertical air legs of the metering block mixing with the fuel leg directly under the high speed air bleed and power valve typically adds 8-10 jet sizes , you can measure the actual size of holes on your own carb and calculate the area as it varies especially when you have a blow through carb on a 1000 plus hp ride .
Like you, I've found that using a power valve a number or two larger than the usually original 6.5" gives me a bit better responsiveness when I floor the throttle. Again, as said, it depends on the engine's amount of manifold vacuum at cruise to be the factor in determining which one to use, but Holley's formula for determining which rating to use usually is on the low side, numerically. If it calls for a 6.5", I'll go with a 7.5". Another thing I'd like to add is to use Holley's type of gray fiber material P/V gasket. I tried using an aftermarket Nylon gasket and I had a problem with the P/V backing out and obviously not sealing as it should. It seems that the nylon isn't a good sealing material because it's too hard for it to compress and if it were to seal, the amount of torque necessary for that to happen is going to get you close to stripping some threads on an expensive metering block and the P/V itself. FYI, the wrench or socket size necessary to fit the power valve is 1 inch. Holley also has two types of the fiber P/V gaskets. The old style has raised tooth like areas on the inner portion of the gasket. The newer type that fits the modern power valves is lacking those raised areas. Use the wrong gasket and the P/V isn't going to seat. Those older style gaskets are usually found in most rebuild kits regardless of who made them. While I mention rebuild kits, never use an off brand part store kit. Always use either a Holley rebuild kit or one of their "Trick Kits". Part store kits are JUNK. You'll run across needle and seat assemblies with the wrong thread sizes and their designs will be completely wrong to function as they should.
+William Charles The power valve has nothing to do with full throttle. It's only for part throttle and high speed enriching purpose. The only way power valve can effect flooring is if the diaphragm is ruptured from a leaning backfire. You will notice on power valves spring tension. Buy a hand vacuum pump with inch pound gauge at your loco parts house and vacuum test the power valve to see if it holds vacuum. Common problem with flooring the car is that the accelerator IE {cam piece, spring tension and gap, passages, diaphragm, spring, check ball and weigh, injection needles , etc. } all have to be tune correctly for a good flooring without spit or sputtering. The best you can do is find a old racing mechanic still working in a shop to tune that carb for you. Because these young kids have to much of the easy life driving fuel injected cars
curtis perry I am an old racing mechanic. I've been turning wrenches for 50 years. Just because a power valve may be open, doesn't mean that it is able to discharge fuel by itself. Fuel discharge from this valve is fully dependent on venturi effect. This is the amount of draw (pressure drop) that's created by the velocity of air that is going through the carb barrels which have a venturi and fuel discharge port inside of each barrel. The only pressurized fuel that is getting discharged out of the carb at any time is from the accelerator pump circuit. All other fuel fuel circuits in the carb depend upon a vacuum being present in the carb's venturi or barrels. A bog or flat spot that's present when the throttle is depressed is usually caused by too little fuel getting discharged out of the accelerator pump discharge nozzles. An increase in pump nozzle size is the usual cure if the accelerator pump's initial adjustment is correct. I always check the opening point on new power valves with a hand held vacuum pump before I install them. I've found as much as one inch of vacuum, plus or minus, variation in their opening point than what their stamped value will indicate.
+William Charles im going to weigh in here. a power valve will open when the manifold vacuum drops below the noted vacuum rating on the valve(within plus or minus reason). the power valve is definitely ripping at full throttle as noted by my afr gauge. when the valve comes in too early, i can note a rich mixture on my gauge and feel the very slight flat spot. oddly enough, as you build rpm your manifold vacuum will tend to increase and at the upper end, your power valve can actually not be adding fuel if vacuum is high enough. truth be told, i set my carbs with the afr gauge. i shoot for 13.5 to 14 cruising, and 12.5 under hard acceleration with no lean or rich spikes. depending on the weight of the vehicle, engine power, carb size, and gearing, power valve settings will always be different.
good afternoon friend I write from of Venezuela my name is jesus I have a holley 600cfm carburetor and I have a problem I smoked spark plugs and it gives me a lot of power failure have to remove and clean all the spark plugs every day that produces much carbon my question is this which should give the carburetor that can regulate and where that nadien not get to help me to regulate the amount of fuel Injection as safe as that would be the cause of the problem and you correct me if I equivoco I thank you very much for the help you can give me this is my mail dj : caiman@gmail.com
+Ismael Rivas sorry for the slow response. I have been overloaded with car repairs. I need to know 3 things first. #1. Remove both front and back bowl sight plugs and start your car. If you can see the gas in the bowl but not spilling out then we are good so far. #2 with car running , look down from top of carburetor and see if gas is dripping from front or back ventures, and is the carburetor making a smooth hiss. #3. While car running, turn each fuel mixture screw all the way in, 1 at a time and notice if the engine and how the engine responds. Then e-mail me the results of your finding. sfperry2003@yahoo.com.
remember too that these valves get damaged diaphragms and the vacuum will pull gas through and really enrich the mixture. I always use a new one if I'm in that far, and especially if the carb has been used and sat around because the diaphragm gets hard and brittle.
on turning in mixtures screw and engine does not stumble doesn't guaranty a bad power valve as someone stated. you could have the float set to high, or crack in the metering block, or incorrect metering block gasket. Two ways you can see if a power valve is bad, bench test with vacuum hand pump or look down from top of ventures and see if gas is dripping sporadically, you will head a popping sound with air filter off at idle.
In the past if you look at Holley books the PV size was determined by taking your vacuum reading at idle and going down 2 sizes. Today for some idiotic reason it changed to 1/2 of your vacuum at idle. I also like to torque mine to specs. Make sure you have the proper PV gasket too, cause there are 2 diff shapes of PV.
The other thing they do now is drill the Pv orifices much larger to really richer the circuit. I have another video come my out soon where I jet drill some set screws and make my own PV jets.
Been having trouble with my boat not having any power at full throddle. Had a bad backfire, then all went to hell. engine runs on 6 or 7 cyl , all plugs become fouled quickly. I am hoping its the power valve as someone mentioned a bad backfire will ruin a power valve. Also having a new coil installed (the coil is checking in at 9.1 ohms and should be between 9.5-15ohms per service manual).everything in the carb must be good because the boat ran fine before the backfire. enjoying these videos,thanks
Definitely sounds like the power valve after a backfire through the carb. So, this happened because it was lean. Jet up 2 sizes and see how she responds on the top end. (Make sure your fuel pressure is consistent at rpm or else you will be lean as well)
we will find out this weekend.i am worried the idle screws, accelerator pump, have been messed with and i dont have a vaccum guage ,or know how to adjust it.The carb will be rebuilt this winter for sure.Thanks
It was the power valve.Installed a new one and boat runs well.adjusted idle mix screws, started at 1 and 1/2 out (12 inch vaccum) and slowly got to 17 inch vaccum max. But the only thing that concerns me is the idle screws are 1/2 turn from bottoming out.Will the engine backfire again? because I am assuming I am running lean. Boat runs great at this setting.Any suggestions?
302 mercruiser. idles at 800rpm then drops to 700-750 in gear.it would bang into gear around 900rpm.Manual says 550-600 in gear,motor wants to quit at 600 rpm,and idle screw feels like it is close to bottomed out already. I have seen your video where you set the idle with t slot slightly exposed.Carb is a 450cfm 4160 holley.
Sweet I think I just figured out which part I need to change next on this poorly performing off road avenger 670... trouble with secondaries not opening, changed diaphragm and unplugged the port, now she breathes but still has a lean stumble and isn't getting the fuel... I think this is next. float levels are fine...
while i'm waithing in myy carb cheater i'm adjusting my quick fuel 650 with a wideband gauge. I have a 331 stroker with a 290/290 comp cams wit 230/230 on 50 . My idle vacuum is 11.5 but my cruising is 14.5 afr at 15-16 inches steady throtlle and steady speed but when i wanna put a litlle more throtlle in it for getting on a small incline the car stutters and afr is going to 16.5 afr so i tested with my throtlle and vacuum gauge and when i'm throtling to 13inches yhe carb richens out . what powervalve do you recommend? there is now a 6.5 in it thanks for helping
I live in California, ugh, and I have to replace power valves about every 8-10 months because the ethanol kills them. My buddy uses a Edelbrock AFB in his '75 El Camino and doesnt have that problem because it doesnt use power valves.
You don't drive enough then. We have 15 percent ethanol and I never have to replace them. But yes that is true, if your car sits a lot, your better off with the eddy spring and needle design
@@ThunderHead289 I drive both my cars almost every day (one has a Holley 2300 and the other has a Motorcraft 2150) and this problem happens all the time with both of them. Just last week, the 2150 was running like crap on startup and would clear up. Then I let it sit for a couple of hours and did the same thing. The next morning, I removed the power valve cover and it was full of gas!
Anytime the metering block is removed turn it around and look at the vacuum side, if it's wet with fuel it's shot. Sucking fuel right out of the bowl. Most of them are short lived with todays fuel. The pv plug and rejet idea is good.
You might need to file the carb body flat than, most are warped/crooked and dont provide a good seal. File on it, you'll see quite a few thousandths where the file doesnt touch metal.
I am going to be that guy........you stated that manifold vacuum pulls on the jets......that is incorrect! Manifold vacuum pulls on the idle circuits because they are located under the throttle plates where manifold vacuum exists. The boosters pull on the jets due to airflow through the Venturi which creates a low pressure area (Venturi effect) which in turn pulls on the jets. Otherwise a great informative video!
Hello all! Question. When we adjust our Idle mixture screws using a Vacuum gauge, Do we need to have it idleing in park or in gear?Then take the highest number we get and divide by two for powervalve needed? Thank you very much!
If you turn in the mixture screws and the engine stumbles your power valve is NOT blown. If you have both screws ALL THE WAY clockwise and the engines didn't drop RPM's then the power valve needs replaced.
i do have a truck cam I agree i think ten is too much...right now im running the 6.5 and its doing good......just dont know the carb well enough yet to really be able to read it well
I have a holley 600 Vac 2nd, I just had my carb tuned, dropped down to 63 jets.. Has a real slight off idle stumble.. Should I move my PV up to a 7.5 from 6.5? Last I checked I was pulling 14 1/2 vacumm.. I was told I could just richen my idle screws up 1/8.
I’m running 2 Holley 450’s on a cross ram intake on a 350 Chevy. After a couple backfires several years ago, I had someone go through the carbs. He actually blocked off the power valves. He said the carbs are a little too much for what I’m running. Hasn’t been a problem except for today. Started running like crap and backfiring again. I’d stop and let the vehicle sit for a bit. It started back up and ran ok for a few minutes. I finally got it home. Fuel wasn’t pouring out so I don’t believe the floats are stuck. Tomorrow I’ll check the plugs. Any other suggestions or thoughts on what’s causing my issue?
hi 30--50mph main jets 40--75 % of primary throttle 14-15:1 A/F PV at engine vacummn open at 45mph 75--100% of throttle of primary 13:1---13.5 :1a/f mixture set by PVR On a vac/ sec the sec jets are +8 up jet sizes 12.5 :1a/f max effort
could really use some help, just added a new 670 Brawler to my 468, my understanding is that the power valve opens when the vacuum drops, so here is my situation, my truck with the large cam drops to 5hg of vacuum on idle in gear so the power valve would normally be open unless i go to the 2.5hg power valve,, what is the best way to set this up
350 sbc solid flat tappet cam vortec heads street warrior carb jegs performer intake full exhaust 6 speed trans 4.10 gear 3400 pound car 10 inches of hg 66 jets stock 6.5 pv vacuum secondarys. ? Is should I put a 4.5 pv in or leave it alone
the one i have has NO power valves at all . Front screw in block off and rear is factory blocked. 4777 series 77 up front and 80 in the back is that normal?
Is manifold vacuum the same thing as the vacuum I have from a vacuum pump on front of my motor ??? Jw because at idle my vacuum is like 2 inches. At WOT i have it set for around 11 inches of vacuum.
The more race oriented the engine is built, you dont want to go all the way down to the ÷2 method of vacuum #, you want to keep the number of your power valve a little higher.
this vid has been very helpful to me, ive put a 4150 650 dp on my 85 dodge 318 and im trying to get it fine tuned for economy. its a huge improvement over the 6280 i had on it from the factory, do you have any hints on high altitude jetting? i am running 62 primary and 70 secondary with a 6.5 power valve. any suggestions would be helpful!
+Kyle Redman from my experience with driving to virginia from iowa, for about 1800 to 2300 feet i had to pull one jet size. the carb is factory set for sea level, so if you have 68 jets stock and are sitting at 2000 feet, you will most likely need a 67 if the jetting was 100 percent correct previously. does this make sense?
the kit i got comes with 2 6.5s and one 10. Would the 10 be too much? Sorry to sound dumb but this is my first time with a 4150, and i must say so far i love the thing, im actually trying to see if i can get a manifold and a bigger version carb for my 64 buick wildcat 401 nailhead........great carb!
+Kyle Redman it all depends where your manifold vacuum is at! 10 is way too much id think unless you have a truck cam. go with the 6.5 if you have to choose between the two!
When tuning for wot if it's sluggish with the pedal to the floor wot then as you let off it accelerated slightly is the power valve to big ? Or too small ?
Sounds like your lean at wot, when you back off and gain power it's because your cutting off the airflow some and the mixture gets better. Main jet change is what you need not power valve.
@@bobstephens8851 yeah it's lean on top, but if your cruise is nice and lean with no lean stumble, you should slowly go up in size with the pvcr. Drill em out 0.002" to 0.003" at a time until your Wot keeps pulling power nicely.
Have you ever tried adjusting the power valve itself? Looks to me like you can get one in the range needed and then adjust the pressure being applied to the spring? It looks like a threaded rod with a round end capturing the spring, so tightening it may increase the power valve number and loosening it may reduce the power valve number. I don't think it would work to adjust it more than 1 size since there are different springs weights and different valve seats from what I can observe, but I think a person could fine tune the power valve a bit. What are your thoughts on that?
+ThunderHead289 I was thinking more along the lines of tuning than expense. If it makes sense to custom tune a metering block with specific restriction sizes for a power valve, does it make sense to adjust the timing of the power valve opening to something more specific than 1" increments? I'm using a 2 barrel Holley 4412 on a Ford 390, and having no secondaries really makes tuning a lot more challenging than it probably would be with a 4 barrel.
on a 650 Dbl Pumper, First remove the power valve and put a holley power valve plug in its place. Yes take it out and throw it in a drawer. Next install new jets at least 3 steps up from what is in there from the factory. Lastly block off the vacuum advance. of course you will have to adjust the timing a bit but you will notice a big difference in performance .the above is only recommended for high performance engines.......
Consider the idle vacuum rule is faulty lore or a over simplistic rule of thumb. One needs to know the vacuum at steady cruise, and set pv to be assured closed for cruise economy and open at lower vacuum, higher load. One use of the pv plug is to set the mains for best lean cruise with confidence. It's not about decreased flow through the mains due to drop in vacuum, its the engine requires 25% more fuel to switch from 14.5:1 lean cruise to 12.5:1 high load mode. The pvco's in the metering block set the extra flow, the pv decides when it comes on. With a few jetting tests, one can then plug and precisely drill new pvco's so both modes are optimal when pv is installed. 'universal' holleys are notoriously rich, to keep hobbiests from fragging their engines and H being blamed. Seems only the application specific carbs, and medium duty truck and marine carbs seem set spot on out of the box.
Great video! I have a Holley 600, idle tuned to the peak performance without a load. Everytime I turn on my fan motor (heater/def or AC) she wants to stall. Would increasing the power valve have any effect on the performance issue when it's under load? (my timing is also set at 12 deg due to a bigger cam if that has any bearing)
i do not think so. it sounds like when the engine gets under a load, the vacuum is such that the power valve could be inopportunely opening, causing a rich condition based on your primary jetting. can you give me some info first? whats the cam lift, is it a manual or auto? what is the rear gear ratio?
Intake Exhaust .510 .512 gross valve lift 268 280 duration @ .006 tappet lift .3190 .3200 Lobr Lift FMX Automatic transmission with a 2500 RPM torque convertor Rear gear is factory 300 9" I hope this helps...I'm considering buying a anti stall solenoid that Holley sells, to see if that helps the stall issue when my AC is on. My jet size is 62
TH289, ElkyLou here. My Sbc 350 build with TH350 auto-trans. Holley1989 1850 Carb, 6.5 PV, stock jets. in in my El Camino 84. Starts on turn -a-key and runs like a sewing machine. Used vacuum gauge to set idle mixer 20Hg at Idle, 18Hg in gear. still Stumbles when I accelerate. Holley suggested going up from 31 nozzle to 35. I'm looking to resolve this issue alone with getting better mileage. Any suggestion would appreciate.
hmmm what is your initial timing set at and what is your transfer slot setting? if there is too much transfer slot exposed, you will get a hard lean bog off the line. let me know your thoughts
I really appreciate you taking your time to get back to me on this issue. First step, before switching up nozzle, you suggest to get the initial timing to you. I'll will need time to remove the Carb to see the transfer slots as you explained in your video. I will say this; when it comes to Carburetors, you know what you're talking about as seen in all your videos.Thank you for all your help.
TH289, so far here's I checked initial timing Idel 10 deg., 3500-34 deg. I'll need the weekend to pull the Carb and check transfer slots unless you see by the Initial time numbers, it wont be necessary.
@@ThunderHead289 I think I have an idle circuit issue? I had a block off in the rear metering block that I switched for another power valve I think it's pouring fuel in the carb I'm parting it together from other carbs
TH289, ElkyLou here. Slight bog of the line. My Sbc 350 build with TH350 auto-trans. Holley1989 1850 Carb, 6.5 PV, stock jets. in in my El Camino 84. TH289, so far here's what I found. You asked me to checked initial timing, Idel 10 deg., 3500rpm-34 deg. Tranfer slots fine. Slight hesitation off the line. Do you suggest moving up nozzle from 31 to 35?
I have a quick fuel hot rod 780. vacuum secondary, single pumper, secondary power valve factory blocked off. my jets are 73/76. car runs strong. why doesn't this Carb need big jet spacing like a double pumper does?
+Raymond Crespo thats strange, it is hard to tell what exactly it might be doing at higher rpm without an afr gauge. my guess it has something to do with opening rates. on my cars, they get leaner at higher rpm so i have to jet my carbs for what rpm i tend to rip on them at moreso. that interesting, never seen spacing quite that close in carb jetting.
nice. awesome that you have a gauge. there are many things that factor into why that could be based on your engine combo. those are awesome numbers, could lean her off one jet size on the secondaries if your not running 10 percent ethanol gas. i like to be 12.5 -13.5 as long as im not detonating.
thats what i idle at and what i run in my car. works well. on my cruiser i can run it leaner with a closer power valve. on a car your ripping on, your right on the money. it really doesnt matter what your carb combo is, as long as the afr's are right
ThunderHead289, my engine is pulling a vacuum reading of 15 so do I bump up to a 7.5 or stick with the stock 6.5 power valve? I am running a Holley 600 on a cammed 305 sbc with a 700r4 and 241 gears in the rear it's a 77 cutlass not sure of total weight. Any help would be greatly appreciated! Trying to cure a stumble. I have 67 jets in and 28 nozzle and blue cam, but have a stumble mid way between 1st and 2nd.
+ostwo thanks for your info! I have made an improvement by setting cam (orange) in the #2 position and raised the idle to just under a grand and in gear to around 750rpm I too am running a 31now get a lot better response and performance. Again thank you for replying!
That was exactly what I needed...thank you.. I've a 67 galaxie 500.. stock 289.. stock gearing.. automatic trans. Can u recommend a jet size? I've a 600 holley.. thanks Scott
600 Holley's are usually good out of the box for stock engines. You can check the plugs for color but with E10 gas it's harder than it used to be. Feel for lean surging under full throttle.
@@bobstephens8851 ill be pulling the plugs tonight to check coloring.. also picked up a power valve and a accelerator diaphram.. hope it clears up my issues
Use this as an example. If your idle vacuum is 13 and there is a power valve that is 7.5, as the vacuum drops during acceleration it will reach 7.5 before it would reach 5.5 which means it will open sooner with the bigger number.
When measuring your idle vacuum, do you divide based off of your vacuum idle in park or while in drive ? In park I idle at 22" does that mean I need an 11 power valve ? Or do I need to check my vacuum while in drive ?
I applaud your effort, but you need to study up. They changed how they mark power valves. I could see in the video the markings. Jetting effects your needed 13:1 fuel ratio. Power valve has no bearing on jet size. Upon open throttle the accelerator pump gives the motor the needed shot, then under low vacuum/heavy load the power valve steps in. And your method of removing the jet blocks is not going to work in most carbs I encounter, which is 2-300 per year.
+david smith how are you sure its rich? she juts idles down and shuts down? pressure needs to be regulated to 6.5 maximum on a bras s float holley, hot carb conditions and pressure spikes will cause things to go all to hell at idle. geta handle on your pressure and float height while the engine idles. i run a carb spacer to also keep the heat off. make sure your mix screws are correct. start with them 2.5 turns out and adjust with a vacuum gauge when engine is fully warmed. your looking for the highest vacuum reading, and then turn the screws a quarter to a half turn richer(out) from there. this make sense? check your timing - im sure your idle timing is between 10-15 degrees mechanical.
love the flag decal on the dash of the truck!!! such a shame this new generation continues to deface and destroy families heritage, and no one does a thing about it...just about criminal
+david smith whats your vacuum at idle and dynamic compression? i did a 12:1 static engine with 9 dynamic and it ran off an 850. 850 is pretty large. i dont know what to tell you, IF you make good manifold vacuum, your pressure is regulated with a consistant proper float height, heat is off the carb with as spacer or heat deflector, mix screws set right, and a proper initial timing setting it should honestly be able to idle. im assuming you have a new air filter on as well. dont overlook any of those aspects, or your idle will be fubared. id have to be standing right in front of your vehicle to really be able to diagnose
Edelbrocks use tapered needles into the jet, with the needles held in place by springs, at high vacuum the needles are pulled down restricting the jet, when vacuum drops at wot the needles lift and the thinner part of the needle is allowing more flow to the jet. The springs coming in different tensions to adjust the transition at different vacuum levels
@@ThunderHead289 My 600 Edy runs 13.0's in the quarter. Too many myths about Edelbrock carbs, just because people don't know how to tune them. I've been fighting with Holley's trying to get them to do better than the Edy, no luck so far.. and I've been tuning Holley's for 30 years.. Leaky, power valve blowing nightmares.
Your videos are underrated. Thank you for what you do.
Good video you seem to want to share information rather than just try to impress thank you very informative.
Thanks for sharing your philosophy on the whole power valve mechanism.
+mark teague no problem, i have started to go through a carb series where im going to explain all my basic holley carb tuning points. you can find it on my channel under recent uploads. im doing a jet video today.
good
afternoon friend I write from of Venezuela my name is jesus I have a
holley 600cfm carburetor and I have a problem I smoked spark plugs and
it gives me a lot of power failure have to remove and clean all the
spark plugs every day that produces much carbon my
question is this which should give the carburetor that can regulate and
where that nadien not get to help me to regulate the amount of fuel
Injection as safe as that would be the cause of the problem and you
correct me if I equivoco I thank you very much for the help you can give me this is my mail dj : caiman@gmail.com
@@ThunderHead289 so is a Holley power valve the same thing basically as a accelerator pump on a 2V? I am trying to solve a issue on my stock 351M 2V thats in a 77 f150. It idles great but starts breaking up around 2500 rpms, even worse under load. Ignition timing set at 10° So far I have replaced plugs, rotor & button, ignition coil & connector, voltage regulator, alternator and battery. Looked under the hood at night and there's no spark jump from wires at all.
the quality of sound reminds me of the old high school reel movies that you never watched since you were too busy thinking of the dynamite chick sittin a few tables away from ya
I run 58 primary jets and 72 secondary with a block off plate on my 850 dp,so it's actually a lot more like 10-14 sizes higher for your secondaries.thank you I enjoyed the video very much..
850? I wouldn`t think an 850 would run that lean. 80 and 86, with back power valve plugged, would be a starting point. Hell, even a 650 would use 67`s.
Good video but behind the power valve are the two pvcr ( power valve channel restricters) the emulsion bleeds are on the the vertical air legs of the metering block mixing with the fuel leg directly under the high speed air bleed and power valve typically adds 8-10 jet sizes , you can measure the actual size of holes on your own carb and calculate the area as it varies especially when you have a blow through carb on a 1000 plus hp ride .
Excellent video, good explanation much better than that SUMMIT guy, thank you for taking the time to teach us
Like you, I've found that using a power valve a number or two larger than the usually original 6.5" gives me a bit better responsiveness when I floor the throttle. Again, as said, it depends on the engine's amount of manifold vacuum at cruise to be the factor in determining which one to use, but Holley's formula for determining which rating to use usually is on the low side, numerically. If it calls for a 6.5", I'll go with a 7.5". Another thing I'd like to add is to use Holley's type of gray fiber material P/V gasket. I tried using an aftermarket Nylon gasket and I had a problem with the P/V backing out and obviously not sealing as it should. It seems that the nylon isn't a good sealing material because it's too hard for it to compress and if it were to seal, the amount of torque necessary for that to happen is going to get you close to stripping some threads on an expensive metering block and the P/V itself. FYI, the wrench or socket size necessary to fit the power valve is 1 inch. Holley also has two types of the fiber P/V gaskets. The old style has raised tooth like areas on the inner portion of the gasket. The newer type that fits the modern power valves is lacking those raised areas. Use the wrong gasket and the P/V isn't going to seat. Those older style gaskets are usually found in most rebuild kits regardless of who made them. While I mention rebuild kits, never use an off brand part store kit. Always use either a Holley rebuild kit or one of their "Trick Kits". Part store kits are JUNK. You'll run across needle and seat assemblies with the wrong thread sizes and their designs will be completely wrong to function as they should.
+William Charles The power valve has nothing to do with full throttle. It's only for part throttle and high speed enriching purpose. The only way power valve can effect flooring is if the diaphragm is ruptured from a leaning backfire. You will notice on power valves spring tension. Buy a hand vacuum pump with inch pound gauge at your loco parts house and vacuum test the power valve to see if it holds vacuum. Common problem with flooring the car is that the accelerator IE {cam piece, spring tension and gap, passages, diaphragm, spring, check ball and weigh, injection needles , etc. } all have to be tune correctly for a good flooring without spit or sputtering. The best you can do is find a old racing mechanic still working in a shop to tune that carb for you. Because these young kids have to much of the easy life driving fuel injected cars
curtis perry I am an old racing mechanic. I've been turning wrenches for 50 years. Just because a power valve may be open, doesn't mean that it is able to discharge fuel by itself. Fuel discharge from this valve is fully dependent on venturi effect. This is the amount of draw (pressure drop) that's created by the velocity of air that is going through the carb barrels which have a venturi and fuel discharge port inside of each barrel. The only pressurized fuel that is getting discharged out of the carb at any time is from the accelerator pump circuit. All other fuel fuel circuits in the carb depend upon a vacuum being present in the carb's venturi or barrels. A bog or flat spot that's present when the throttle is depressed is usually caused by too little fuel getting discharged out of the accelerator pump discharge nozzles. An increase in pump nozzle size is the usual cure if the accelerator pump's initial adjustment is correct. I always check the opening point on new power valves with a hand held vacuum pump before I install them. I've found as much as one inch of vacuum, plus or minus, variation in their opening point than what their stamped value will indicate.
+William Charles im going to weigh in here. a power valve will open when the manifold vacuum drops below the noted vacuum rating on the valve(within plus or minus reason). the power valve is definitely ripping at full throttle as noted by my afr gauge. when the valve comes in too early, i can note a rich mixture on my gauge and feel the very slight flat spot. oddly enough, as you build rpm your manifold vacuum will tend to increase and at the upper end, your power valve can actually not be adding fuel if vacuum is high enough. truth be told, i set my carbs with the afr gauge. i shoot for 13.5 to 14 cruising, and 12.5 under hard acceleration with no lean or rich spikes. depending on the weight of the vehicle, engine power, carb size, and gearing, power valve settings will always be different.
good
afternoon friend I write from of Venezuela my name is jesus I have a
holley 600cfm carburetor and I have a problem I smoked spark plugs and
it gives me a lot of power failure have to remove and clean all the
spark plugs every day that produces much carbon my
question is this which should give the carburetor that can regulate and
where that nadien not get to help me to regulate the amount of fuel
Injection as safe as that would be the cause of the problem and you
correct me if I equivoco I thank you very much for the help you can give me this is my mail dj : caiman@gmail.com
+Ismael Rivas sorry for the slow response. I have been overloaded with car repairs. I need to know 3 things first. #1. Remove both front and back bowl sight plugs and start your car. If you can see the gas in the bowl but not spilling out then we are good so far. #2 with car running , look down from top of carburetor and see if gas is dripping from front or back ventures, and is the carburetor making a smooth hiss. #3. While car running, turn each fuel mixture screw all the way in, 1 at a time and notice if the engine and how the engine responds. Then e-mail me the results of your finding. sfperry2003@yahoo.com.
yes this does make sense it is running great on 62s and 70s, getting great fuel milage but was more concerned with power valves
remember too that these valves get damaged diaphragms and the vacuum will pull gas through and really enrich the mixture. I always use a new one if I'm in that far, and especially if the carb has been used and sat around because the diaphragm gets hard and brittle.
Such brilliance
on turning in mixtures screw and engine does not stumble doesn't guaranty a bad power valve as someone stated. you could have the float set to high, or crack in the metering block, or incorrect metering block gasket. Two ways you can see if a power valve is bad, bench test with vacuum hand pump or look down from top of ventures and see if gas is dripping sporadically, you will head a popping sound with air filter off at idle.
Pretty decent explanation. Thank you I have a better understanding on how power valves work
In the past if you look at Holley books the PV size was determined by taking your vacuum reading at idle and going down 2 sizes. Today for some idiotic reason it changed to 1/2 of your vacuum at idle. I also like to torque mine to specs. Make sure you have the proper PV gasket too, cause there are 2 diff shapes of PV.
The other thing they do now is drill the Pv orifices much larger to really richer the circuit.
I have another video come my out soon where I jet drill some set screws and make my own PV jets.
Well keep reading the Holley carburetor book , your getting closer.
Been having trouble with my boat not having any power at full throddle. Had a bad backfire, then all went to hell. engine runs on 6 or 7 cyl , all plugs become fouled quickly. I am hoping its the power valve as someone mentioned a bad backfire will ruin a power valve. Also having a new coil installed (the coil is checking in at 9.1 ohms and should be between 9.5-15ohms per service manual).everything in the carb must be good because the boat ran fine before the backfire. enjoying these videos,thanks
Definitely sounds like the power valve after a backfire through the carb. So, this happened because it was lean. Jet up 2 sizes and see how she responds on the top end. (Make sure your fuel pressure is consistent at rpm or else you will be lean as well)
we will find out this weekend.i am worried the idle screws, accelerator pump, have been messed with and i dont have a vaccum guage ,or know how to adjust it.The carb will be rebuilt this winter for sure.Thanks
It was the power valve.Installed a new one and boat runs well.adjusted idle mix screws, started at 1 and 1/2 out (12 inch vaccum) and slowly got to 17 inch vaccum max. But the only thing that concerns me is the idle screws are 1/2 turn from bottoming out.Will the engine backfire again? because I am assuming I am running lean. Boat runs great at this setting.Any suggestions?
+lonecedarfarm what is your idle rpm? You may have your transfer slots open too far and it's feeding in fuel. What size engine with what size carb?
302 mercruiser. idles at 800rpm then drops to 700-750
in gear.it would bang into gear around 900rpm.Manual says 550-600 in gear,motor wants to quit at 600 rpm,and idle screw feels like it is close to bottomed out already. I have seen your video where you set the idle with t slot slightly exposed.Carb is a 450cfm 4160 holley.
Sweet I think I just figured out which part I need to change next on this poorly performing off road avenger 670... trouble with secondaries not opening, changed diaphragm and unplugged the port, now she breathes but still has a lean stumble and isn't getting the fuel... I think this is next. float levels are fine...
So after your done you put the carb on a flow bench right? or your a l tune by ear kinda guy?.
while i'm waithing in myy carb cheater i'm adjusting my quick fuel 650 with a wideband gauge.
I have a 331 stroker with a 290/290 comp cams wit 230/230 on 50 .
My idle vacuum is 11.5 but my cruising is 14.5 afr at 15-16 inches steady throtlle and steady speed but when i wanna put a litlle more throtlle in it for getting on a small incline the car
stutters and afr is going to 16.5 afr so i tested with my throtlle and vacuum gauge and when i'm throtling to 13inches yhe carb richens out .
what powervalve do you recommend? there is now a 6.5 in it
thanks for helping
I live in California, ugh, and I have to replace power valves about every 8-10 months because the ethanol kills them. My buddy uses a Edelbrock AFB in his '75 El Camino and doesnt have that problem because it doesnt use power valves.
You don't drive enough then. We have 15 percent ethanol and I never have to replace them.
But yes that is true, if your car sits a lot, your better off with the eddy spring and needle design
@@ThunderHead289 I drive both my cars almost every day (one has a Holley 2300 and the other has a Motorcraft 2150) and this problem happens all the time with both of them. Just last week, the 2150 was running like crap on startup and would clear up. Then I let it sit for a couple of hours and did the same thing. The next morning, I removed the power valve cover and it was full of gas!
You explained it well. Thanks
... thanks again for the KNOWLEDGE. 👍👍💯💯💯💯🎬
Anytime the metering block is removed turn it around and look at the vacuum side, if it's wet with fuel it's shot. Sucking fuel right out of the bowl. Most of them are short lived with todays fuel. The pv plug and rejet idea is good.
Robert Eskins I put out a series on carb tuning recently or I guess within the last two years. Really the most straight forward for understanding
You might need to file the carb body flat than, most are warped/crooked and dont provide a good seal. File on it, you'll see quite a few thousandths where the file doesnt touch metal.
I am going to be that guy........you stated that manifold vacuum pulls on the jets......that is incorrect! Manifold vacuum pulls on the idle circuits because they are located under the throttle plates where manifold vacuum exists. The boosters pull on the jets due to airflow through the Venturi which creates a low pressure area (Venturi effect) which in turn pulls on the jets. Otherwise a great informative video!
Hello all! Question. When we adjust our Idle mixture screws using a Vacuum gauge, Do we need to have it idleing in park or in gear?Then take the highest number we get and divide by two for powervalve needed? Thank you very much!
If you turn in the mixture screws and the engine stumbles your power valve is NOT blown. If you have both screws ALL THE WAY clockwise and the engines didn't drop RPM's then the power valve needs replaced.
Thank you...I needed that information.
I can wind in the driver's side idle mixture screw all the way & it does nothing.
But if I wind in the passenger side screw it almost stalls
Unless, both idle fuel orifices are plugged, and someone upped the idle screw till it's idleing on the transfer slots that get fuel from the mains
i do have a truck cam I agree i think ten is too much...right now im running the 6.5 and its doing good......just dont know the carb well enough yet to really be able to read it well
Actually doesn't vacuum hold the PV closed? When vac drops the valve opens? Thanks for all your informative vids...
Im not sure what i said in the video, but yes - you are 100 percent correct on that.
You explained it correctly and I have no doubt that this will help people.
Yes
great explanation.
I have a holley 600 Vac 2nd, I just had my carb tuned, dropped down to 63 jets.. Has a real slight off idle stumble.. Should I move my PV up to a 7.5 from 6.5? Last I checked I was pulling 14 1/2 vacumm.. I was told I could just richen my idle screws up 1/8.
You going to come up here and help me set up my carb on my ls
I’m running 2 Holley 450’s on a cross ram intake on a 350 Chevy. After a couple backfires several years ago, I had someone go through the carbs. He actually blocked off the power valves. He said the carbs are a little too much for what I’m running. Hasn’t been a problem except for today. Started running like crap and backfiring again. I’d stop and let the vehicle sit for a bit. It started back up and ran ok for a few minutes. I finally got it home. Fuel wasn’t pouring out so I don’t believe the floats are stuck. Tomorrow I’ll check the plugs.
Any other suggestions or thoughts on what’s causing my issue?
hi 30--50mph main jets 40--75 % of primary throttle 14-15:1 A/F
PV at engine vacummn open at 45mph 75--100% of throttle of primary 13:1---13.5 :1a/f mixture set by PVR
On a vac/ sec the sec jets are +8 up jet sizes 12.5 :1a/f max effort
Good job.
could really use some help, just added a new 670 Brawler to my 468, my understanding is that the power valve opens when the vacuum drops, so here is my situation, my truck with the large cam drops to 5hg of vacuum on idle in gear so the power valve would normally be open unless i go to the 2.5hg power valve,, what is the best way to set this up
350 sbc solid flat tappet cam vortec heads street warrior carb jegs performer intake full exhaust 6 speed trans 4.10 gear 3400 pound car 10 inches of hg 66 jets stock 6.5 pv vacuum secondarys. ? Is should I put a 4.5 pv in or leave it alone
the one i have has NO power valves at all . Front screw in block off and rear is factory blocked. 4777 series
77 up front and 80 in the back is that normal?
i was the 420th like....i can die happy now
Is manifold vacuum the same thing as the vacuum I have from a vacuum pump on front of my motor ??? Jw because at idle my vacuum is like 2 inches. At WOT i have it set for around 11 inches of vacuum.
The more race oriented the engine is built, you dont want to go all the way down to the ÷2 method of vacuum #, you want to keep the number of your power valve a little higher.
this vid has been very helpful to me, ive put a 4150 650 dp on my 85 dodge 318 and im trying to get it fine tuned for economy. its a huge improvement over the 6280 i had on it from the factory, do you have any hints on high altitude jetting? i am running 62 primary and 70 secondary with a 6.5 power valve. any suggestions would be helpful!
+Kyle Redman from my experience with driving to virginia from iowa, for about 1800 to 2300 feet i had to pull one jet size. the carb is factory set for sea level, so if you have 68 jets stock and are sitting at 2000 feet, you will most likely need a 67 if the jetting was 100 percent correct previously.
does this make sense?
the kit i got comes with 2 6.5s and one 10. Would the 10 be too much? Sorry to sound dumb but this is my first time with a 4150, and i must say so far i love the thing, im actually trying to see if i can get a manifold and a bigger version carb for my 64 buick wildcat 401 nailhead........great carb!
+Kyle Redman it all depends where your manifold vacuum is at! 10 is way too much id think unless you have a truck cam. go with the 6.5 if you have to choose between the two!
ThunderHead289 hj
When tuning for wot if it's sluggish with the pedal to the floor wot then as you let off it accelerated slightly is the power valve to big ? Or too small ?
Sounds like your lean at wot, when you back off and gain power it's because your cutting off the airflow some and the mixture gets better. Main jet change is what you need not power valve.
@@bobstephens8851 yeah it's lean on top, but if your cruise is nice and lean with no lean stumble, you should slowly go up in size with the pvcr. Drill em out 0.002" to 0.003" at a time until your Wot keeps pulling power nicely.
Have you ever tried adjusting the power valve itself? Looks to me like you can get one in the range needed and then adjust the pressure being applied to the spring? It looks like a threaded rod with a round end capturing the spring, so tightening it may increase the power valve number and loosening it may reduce the power valve number. I don't think it would work to adjust it more than 1 size since there are different springs weights and different valve seats from what I can observe, but I think a person could fine tune the power valve a bit. What are your thoughts on that?
+mmoecnc i have never tried it, but if you dont want to pay 2 bucks for a power valve, i suppose it could be done for sure
+ThunderHead289 I was thinking more along the lines of tuning than expense. If it makes sense to custom tune a metering block with specific restriction sizes for a power valve, does it make sense to adjust the timing of the power valve opening to something more specific than 1" increments? I'm using a 2 barrel Holley 4412 on a Ford 390, and having no secondaries really makes tuning a lot more challenging than it probably would be with a 4 barrel.
on a 650 Dbl Pumper, First remove the power valve and put a holley power valve plug in its place. Yes take it out and throw it in a drawer. Next install new jets at least 3 steps up from what is in there from the factory. Lastly block off the vacuum advance. of course you will have to adjust the timing a bit but you will notice a big difference in performance .the above is only recommended for high performance engines.......
Let it be known that this is for race application only! This methodology will kill your fuel economy
Most racers only plug the secondary.
@@donrutter6765 agree my quick fuel came with the secondaries have a plug but tell ya to jump 6 to 8 settings in back with plug
Consider the idle vacuum rule is faulty lore or a over simplistic rule of thumb.
One needs to know the vacuum at steady cruise, and set pv to be assured closed for cruise economy and open at lower vacuum, higher load.
One use of the pv plug is to set the mains for best lean cruise with confidence.
It's not about decreased flow through the mains due to drop in vacuum, its the engine requires 25% more fuel to switch from 14.5:1 lean cruise to 12.5:1 high load mode.
The pvco's in the metering block set the extra flow, the pv decides when it comes on.
With a few jetting tests, one can then plug and precisely drill new pvco's so both modes are optimal when pv is installed.
'universal' holleys are notoriously rich, to keep hobbiests from fragging their engines and H being blamed.
Seems only the application specific carbs, and medium duty truck and marine carbs seem set spot on out of the box.
Great video! I have a Holley 600, idle tuned to the peak performance without a load. Everytime I turn on my fan motor (heater/def or AC) she wants to stall. Would increasing the power valve have any effect on the performance issue when it's under load? (my timing is also set at 12 deg due to a bigger cam if that has any bearing)
i do not think so. it sounds like when the engine gets under a load, the vacuum is such that the power valve could be inopportunely opening, causing a rich condition based on your primary jetting. can you give me some info first? whats the cam lift, is it a manual or auto? what is the rear gear ratio?
Intake Exhaust
.510 .512 gross valve lift
268 280 duration @ .006 tappet lift
.3190 .3200 Lobr Lift
FMX Automatic transmission with a 2500 RPM torque convertor
Rear gear is factory 300 9"
I hope this helps...I'm considering buying a anti stall solenoid that Holley
sells, to see if that helps the stall issue when my AC is on. My jet size is 62
thats a sizely cam, but a decent stall. on your deal here, id go with the old holley way, and set your power valve to half of your idle vacuum
Skip Barrus g
On hotter cams, dont put a power valve at half the vacuum #, go a tad higher. If the math says you need a #6, try a number 6.5 - 7.
TH289, ElkyLou here. My Sbc 350 build with TH350 auto-trans. Holley1989 1850 Carb, 6.5 PV, stock jets. in in my El Camino 84.
Starts on turn -a-key and runs like a sewing machine. Used vacuum gauge to set idle mixer 20Hg at Idle, 18Hg in gear. still Stumbles when I accelerate. Holley suggested going up from 31 nozzle to 35. I'm looking to resolve this issue alone with getting better mileage.
Any suggestion would appreciate.
hmmm what is your initial timing set at and what is your transfer slot setting? if there is too much transfer slot exposed, you will get a hard lean bog off the line. let me know your thoughts
I really appreciate you taking your time to get back to me on this issue.
First step, before switching up nozzle, you suggest to get the initial timing to you. I'll will need time to remove the Carb to see the transfer slots as you explained in your video. I will say this; when it comes to Carburetors, you know what you're talking about as seen in all your videos.Thank you for all your help.
TH289, so far here's I checked initial timing Idel 10 deg., 3500-34 deg.
I'll need the weekend to pull the Carb and check transfer slots unless you see by the Initial time numbers, it wont be necessary.
Sir I need help!! I have a 750 dp flooding like hell I have two power valves one on the primary and another on the rear...
If it's by definition flooding, id look to your float height
@@ThunderHead289 I think I have an idle circuit issue? I had a block off in the rear metering block that I switched for another power valve I think it's pouring fuel in the carb I'm parting it together from other carbs
TH289, ElkyLou here. Slight bog of the line. My Sbc 350 build with TH350 auto-trans. Holley1989 1850 Carb, 6.5 PV, stock jets. in in my El Camino 84. TH289, so far here's what I found. You asked me to checked initial timing, Idel 10 deg., 3500rpm-34 deg. Tranfer slots fine. Slight hesitation off the line. Do you suggest moving up nozzle from 31 to 35?
What position is your pump cam in, and is this a relatively stock engine? What does it make for manifold vacuum ?
TH289, cam position #1, SBC 350 1990 block, Pro series 1.5 aluminium rockers, 7116 Edelbrock performer intake dual plane, Aluminium pistons,
Camshaft from Z-28 Camaro, Holley 1850, vacuum reading 20 idel, 18 in drive. auto-trans. TH350.
TH289, cam position #1, SBC 350 1990 block, Pro series 1.5 aluminium rockers, 7116 Edelbrock performer intake dual plane, Aluminium pistons,
Camshaft from Z-28 Camaro, Holley 1850, vacuum reading 20 idel, 18 in drive. auto-trans. TH350.
I have a quick fuel hot rod 780. vacuum secondary, single pumper, secondary power valve factory blocked off. my jets are 73/76. car runs strong. why doesn't this Carb need big jet spacing like a double pumper does?
+Raymond Crespo thats strange, it is hard to tell what exactly it might be doing at higher rpm without an afr gauge. my guess it has something to do with opening rates. on my cars, they get leaner at higher rpm so i have to jet my carbs for what rpm i tend to rip on them at moreso. that interesting, never seen spacing quite that close in carb jetting.
ThunderHead289 idle 13.8 af . cruise 13.9-14.2. Wide open throttle hovers 11.9-12.6
ThunderHead289 13 in vacuum at idle so I went 6.5 pv
nice. awesome that you have a gauge. there are many things that factor into why that could be based on your engine combo. those are awesome numbers, could lean her off one jet size on the secondaries if your not running 10 percent ethanol gas. i like to be 12.5 -13.5 as long as im not detonating.
thats what i idle at and what i run in my car. works well. on my cruiser i can run it leaner with a closer power valve. on a car your ripping on, your right on the money. it really doesnt matter what your carb combo is, as long as the afr's are right
ThunderHead289, my engine is pulling a vacuum reading of 15 so do I bump up to a 7.5 or stick with the stock 6.5 power valve? I am running a Holley 600 on a cammed 305 sbc with a 700r4 and 241 gears in the rear it's a 77 cutlass not sure of total weight. Any help would be greatly appreciated! Trying to cure a stumble. I have 67 jets in and 28 nozzle and blue cam, but have a stumble mid way between 1st and 2nd.
i run orange cam with 31 mozzel 64 main jet that seems to work the best for me
i hame 86 elcamino 355 sbc 3.23 gears 700r4 trans 13 in vac 5.5 pv
+ostwo thanks for your info! I have made an improvement by setting cam (orange) in the #2 position and raised the idle to just under a grand and in gear to around 750rpm I too am running a 31now get a lot better response and performance. Again thank you for replying!
That was exactly what I needed...thank you..
I've a 67 galaxie 500.. stock 289.. stock gearing.. automatic trans. Can u recommend a jet size? I've a 600 holley.. thanks Scott
600 Holley's are usually good out of the box for stock engines. You can check the plugs for color but with E10 gas it's harder than it used to be. Feel for lean surging under full throttle.
@@bobstephens8851 ill be pulling the plugs tonight to check coloring.. also picked up a power valve and a accelerator diaphram.. hope it clears up my issues
@@bobstephens8851 yeah but what if the guy before him put in plugs that are way to cold for his setup?
the new problem with these power valves is leakage right through the gasket. Yes they leak, these news gaskets are shit right from the factory.
best thing to do is use a viton o ring. saw it on some forums and started using it myself. theres a size that fits the outside groove perfectly.
I just rebuilt a 780 and it was leaking around the power valve and fouled my plugs. The gaskets are like cheap card board.. wtf Holley?
question. so what opens sooner, a bigger number or a smaller power valve number?..
The bigger number would open sooner.
Because it requires more vacuum to keep it closed. Right?
Use this as an example. If your idle vacuum is 13 and there is a power valve that is 7.5, as the vacuum drops during acceleration it will reach 7.5 before it would reach 5.5 which means it will open sooner with the bigger number.
When measuring your idle vacuum, do you divide based off of your vacuum idle in park or while in drive ? In park I idle at 22" does that mean I need an 11 power valve ? Or do I need to check my vacuum while in drive ?
+Damian Ramirez I would definitely use your measurement and drive.
dart pro heads 230 intake runners
Any way to check for a bad power valve ?
If you suck on the back of it and pull air through, it’s bad.
If when removed there is fuel in the vacuum chamber behind the power valve, she’s blown.
@@ThunderHead289 Thank you
I applaud your effort, but you need to study up. They changed how they mark power valves. I could see in the video the markings. Jetting effects your needed 13:1 fuel ratio. Power valve has no bearing on jet size. Upon open throttle the accelerator pump gives the motor the needed shot, then under low vacuum/heavy load the power valve steps in. And your method of removing the jet blocks is not going to work in most carbs I encounter, which is 2-300 per year.
do you have any ideas for a super rich idle im at my wits end I built a 383 stroker it pulls hard and runs great but at idle it will run you out
+david smith how are you sure its rich? she juts idles down and shuts down? pressure needs to be regulated to 6.5 maximum on a bras s float holley, hot carb conditions and pressure spikes will cause things to go all to hell at idle. geta handle on your pressure and float height while the engine idles. i run a carb spacer to also keep the heat off.
make sure your mix screws are correct. start with them 2.5 turns out and adjust with a vacuum gauge when engine is fully warmed. your looking for the highest vacuum reading, and then turn the screws a quarter to a half turn richer(out) from there.
this make sense? check your timing - im sure your idle timing is between 10-15 degrees mechanical.
+ThunderHead289 yes I did I even built a carb with anular boosters
Still idling ruch
Dammit rich
annular boosters? how big is your carb?
Compensate is a better word to use here than atone., we are not talking about forgiveness. =)
love the flag decal on the dash of the truck!!! such a shame this new generation continues to deface and destroy families heritage, and no one does a thing about it...just about criminal
Engine vacuum at gear..for Autos
850 cfm
+david smith whats your vacuum at idle and dynamic compression? i did a 12:1 static engine with 9 dynamic and it ran off an 850. 850 is pretty large. i dont know what to tell you, IF you make good manifold vacuum, your pressure is regulated with a consistant proper float height, heat is off the carb with as spacer or heat deflector, mix screws set right, and a proper initial timing setting it should honestly be able to idle. im assuming you have a new air filter on as well.
dont overlook any of those aspects, or your idle will be fubared. id have to be standing right in front of your vehicle to really be able to diagnose
Edelbrock Bullet proof. No power valve needed or mechanic geek.
Definitely is not. That's why I'm going to do a comparison video. Thy leave so much power on the table
ThunderHead289 Holley's are pretty darn easy to fine to tune if you spend some time learning about them. Excellent videos.
Edelbrocks use tapered needles into the jet, with the needles held in place by springs, at high vacuum the needles are pulled down restricting the jet, when vacuum drops at wot the needles lift and the thinner part of the needle is allowing more flow to the jet. The springs coming in different tensions to adjust the transition at different vacuum levels
@@ThunderHead289 My 600 Edy runs 13.0's in the quarter. Too many myths about Edelbrock carbs, just because people don't know how to tune them. I've been fighting with Holley's trying to get them to do better than the Edy, no luck so far.. and I've been tuning Holley's for 30 years.. Leaky, power valve blowing nightmares.