That was some good info on the idle set. You've got that Galaxie sounding really nice. Being a Ford man myself, I like to see and hear something besides what brand X has to offer. On the size of the Allen head screw, (actually called a "set screw"), it's a thread size #10-32 X 3/8" long. Any good hardware store should have them. If you have a problem accessing the screw from the bottom side once the carb is mounted, you can flip the screw around so that the head is on the top side. You'll need to shut the engine down and place the carb at open throttle and move the secondary arm to get the Allen wrench in place to make an adjustment, but it will be easier than having to remove the carb, that's for sure. One more thing that I've discovered on these Holley carbs is that sometimes this screw will have a sloppy fit. To fix this loose fit, you can wrap some Teflon thread sealing tape around the screw to take up the slack and keep the screw in place. I wouldn't use Lock-Tite because sometimes it works too well and you'll strip the Allen head portion of the screw when you try to make an adjustment.
This some of the best advice I've heard. I have a '83 F-250 w/ a 460 and Holley 4160 750 CFM, #73 primary jets and a #25 secondary metering plate @ 6,000 feet elevation. I could either get my carb to idle right and bog at part throttle or idle rich and run great but not both. I had never thought to use the secondaries for idle. Set the choke up, turned the idle screws out 1 1/2 turns from full seat, and left the transfer slots were he said. After it warmed up, my 460 was idling at about 1100 RPM so I turned the curb idle screw out 3/4 turn and now it idles at the proper 650-700 RPM. Pulls like no other and does 40-70 MPH pulls in fourth gear in about four seconds. Thanks, Thunderhead289!
@@briantarka6146 Port matched Cobra Jet heads and intake from a 429. I put a 4150 rear block on the carb so I could jet the rear. #72 in the front, #76 in the rear. 37° of total timing with a 15° vacuum advance. Everything else was the same from earlier.
When I first bought my car and rebuilt the 302, I watched this video and it ran real good. Long story short booms like to touch stuff and my carb has ran not so well recently. Just remembered this video and it is a legendary trick to tuning carbs! What a difference
I bought a car with a Holley 750/mechanical secondaries and your video really helped me get her running just right now. The carb was WAYYYY out. Thanks for the info. Nice and clear video
Good idea with the Allen screw for secondary adjustment. The way I went with that was just flip the secondaries adjustment screw over when carb is off motor so the flat slot is pointing up. It can then be accessible without hassle. Great video btw a lot of good pointers.
If your secondaries come on too late or to early is that the screw you would ajust to compensate for that ? I am switching from a 2bbl to a 4160 street warrior / classic Holly 600 i knew about the transfer slots from this vid awile back thanks 👍 Luke although not sure about how to ajust secondaries .
@@TheThirdWheel618 no there is a plastic cam that controls the ramp the throttle blades open at. You swap the plastic cams to get more aggressive or lazy throttle opening on mechanical carbs.
@@johnsnow1355 thanks now I seen a video where people were turning the carburetor upside down and there was like a little Allen screw at the secondaries and they were cracking that because they don't want to mess with the the slotted area in the primary section so by turning that little Allen screw I guess they open the secondaries a little and it caused the idle to go up without touching the idle screw at all. I have that quick change diaphragm cap I'm assuming to adjust your wide open throttle it's controlled by the stiffness of the spring with them vacuum secondaries I probably would never need it but I bought that kit with the assorted Springs so if I wanted it to come on sooner I would just put the shorter weaker spring and if I wanted my secondaries to open later I would put the longer stiffer spring I'm guessing that's the way it works I doubt if I will ever need it because my engine is not that beefed up it just has a mild cam although I put an Edelbrock RPM on top of my 390 I'm not sure if the 600 CFM with a single feed gas inlet is going to be adequate I'm going to have to play around with it and find out.
Very good advise, optimum transfer slot exposure is .045, which results in the opening being open the same amount as the width, aka “Square” Setting the curb idle with the Secondary throttle blade works great unless you have a really low manifold vacuum. Plus there’s other concerns when your dealing with a 4 corner idle carb in terms of balancing the carb, that’s when you can play with adding small holes in the throttle blades and/or use the Barry Grant idle ease feature. Both ways adding holes/idle ease were implemented to add idle air while maintaining the transfer slot function. Great Video! 👍👍👍
Very informative! Thanks, I just grabbed a used Holley and have been wanting to properly set the idle. This gives me a great place to start and adjust timing from there.
I used a 1 1/2" long screw an put a light film of silicone so it will stay where I left it for vibration control,i adjust it while it's running,works excellent!
I've thought about setting mine up like this. Just swapped my freshly built 327 with a 383 (i couldn't keep up 💨). I built it from scratch, 800 main body, billet aluminum hi flow metering blocks, base plate is tight with all new brass floats and everything. Worked awesome on my 327 then put it on my cj7 jeep 304 for a month then in on the stroker but i swapped the jets from 68 f 74 r to 73 f and 78 rear. Hasn't been right since, I've jetted down, checked for all sorts of possible air leak areas, swapped the power valve but nothing. It'll only idle at a very hi rmp but not in gear unless idled extremely high and if you try to idle it down It'll just die. The more you screw the idle air screws out the higher it idles but no matter what i try it i can't get it back to normal. Going to try your setup this weekend and see how it goes. Motor is .060 bore, scat 9000 3.75 crank/5.7 rod, flycut huge dome pistons, 1969 041X heads shaved to 62cc and running an elgin solid lift 30/30 duntov cam and lifters. Strange that the carb worked flawlessly on my 10.25:1 40 over 327 tight lash isky .465 solid grind and the jeep 304 with a small elgin .465 hyd. I had a 750 vacuum secondary on the 383 the 1st week i ran it and that carb worked good on it but jetted down and on the cj now. Do you think maybe it's throttle plate related, run 2 fuel filters and only run 110 octane turbo blue racing fuel at 12.5:1 compression
Great suggestion on the allen key and allen screw. I have a 90 degree, low-profile screw driver set that I use to adjust this secondary throttle screw.
Any setting over .020 on the slot will cause a very rich idle. You can purchase the Billet base plate from Proform that has a screw on the top side of the secondary shaft for this adjustment. Its just like an idle screw. Lots of people dont want you drilling their primary shaft blades.
Great tip on keeping your high signal strength on your idle circuit with a big cam with really too much over lap, another top would be to incorporate a air bleed off in the center port which I believe Holley has already done.
I took my Carter AFB off my 64 Buick Riviera to check this stuff. The primaries were not even close to square! I readjusted the floats and mounted it up and it works again!! Only thing is the high idle cam does not engage the idle screw and the choke isn't effective. Longer screw? BUT VERY COOL INFOMATION. Keep it up.
A lot of the racers with double pumpers adjust their transfer slots square, then they start out with a smalll drill and drill a hole in each primary butterfly, and possibly step up the drill size.
Hey man, Getting ready to try tuning the carb on my truck I just finished touching every nut and bolt on. I got it to fire up and put around but it's really bad. Had a question though, some of your videos contradict (or rather, use different methods) to setting idle. Sometimes you say use timing, in this you say use secondaries. Which would be the proper way? Are you still tuning your idle with the secondaries mainly? Should I aim for keeping those closed and trying to set idle with timing first, then if I need adjustment, use the secondaries? Thanks a bunch
With my big cam vortec everything square the motor won't even run..... No messing with timing will fix a motor that has under 5inch of vaccum at idle. Would drilling holes in the throttle plates be the way to go with mechanical secondary on a Holley brawler carb. Instead of messing with the secondary throttle blades to let in more air and increase the vacuum.
I have a 383 with a 700r4 and big cam... Idle gives 11 vacuum but once I put into drive it idles too low!!! I need it to be at 1400 to be able to drop it into drive to keep it alive... I was told to adjust the secondaries because of the big cam I have.... Any tips?
Juan, do you have vacuum advance on your distributor? If so, is your hose hooked up to straight manifold vacuum or metered vacuum (ie: off the metering block) ?? Vacuum advance should be hooked up to straight manifold vacuum for proper performance. Try that.
I've recently started learning about these and how to really set up a holley, as I've always used a summit or edelbrock which seem to be fine already when I get them. I have an almost stock 390 FE with an "RV" cam that just has a little more lift/duration than stock. I have a summit distributor and where it's curved right now I need like 15° BTDC initial timing to get 36° total, any if I move the initial down much it really bogs and loses power in the low end and it SEEMS to want more than 15. The problem, my idle is too high. I took the carb off and set the secondary and primary blades so I have just the square of the transfer slow showing. I set the curb idle screw so that it was basically backed out all the way when you could see just the square. Now when I back the screw out all the way with the engine running it's idling too high. Long comment, but is it ok to have less than a square of the transition slot showing? Or even none of it? Basically when I set it by eye with the carb off and I have a square, put it on, it idles too high.
What size is the allen screw? I'll have to give this a try. I should be able to have less throttle plate opening since I have a smaller cam with higher vacuum as well.
1972FordF150 i dont remember the exact size and i dont think i even looked. i pulled the screw out of my carb and compared it against others by putting the threads together. really makes a big difference when you get full transfer slot usage on the primary size. really has cleaned up that lean stumble a lot.
Ive heard time and time again about adjusting the transfer slot exposure even on new carbs. What doesn't make sense to me is if it's so important, why isn't it set "correctly" from the factory right out of the box? I ask this because the new carb i just bought didnt have the transfer slots setup like Ive seen several content creators suggest.
It usually is. Then some meth head starts winging the curb idle screw all over. Edelbrock made a new carb that uses a bypass air valve to adjust idle speed - the way it should have been done from the start.
@@ThunderHead289 I appreciate ur reply, Luke, Thanks. The next question that comes to mind tho is if u shouldn't adjust idle with the curb idle screw....why is it there as an adjustment in the 1st place? As you can probably surmise, I'm no carb guru but I'm trying to overcome my ignorance. And yes, Ive got a carb (Street Demon 625) that's giving me trouble getting it setup on my '72 Camper Special. I'm not finding any adjustment for secondaries that will allow me to alter idle speed and that's not surprising as a Street Demon is a different design from the Holley you used as an example. So I'm still kind of swimming in circles looking for answers to a list of questions like why I lost 20% fuel mileage just by bolting this carb on. And why after the engine is warmed up completely and then shut down, 5 mins later it wont start etc etc....SMH.
Regarding the lawnmower fix(with dirt in the fuel screen), can you make a video that shows how to just take off the gas tank to clean fuel lines, screen, etc. on the exact same Briggs and Stratton engine model that you already have videos of? That would be flipping awesome if ya could! I need to do the exact same thing you did, but I don't want to mess with coil and such...Thanks so much if you do.
Hey enjoying your videos and learning a lot, thank you. I got a vacuum gauge, put in on port and am pulling 5” of vacuum at idle, so i backed off the idle til the vacuum went down to zero and then added timing til it idled decent but it was then at 30 deg. So I backed the timing down to 22 which was as low as i could and still keep it running (about 600 rpm). I was wondering if you had any advice for me. Thanks I have a Holley 4160, big block Mopar. Mostly stock. Mild cam
run a vacuum advance can if you dont . 30 degrees at idle is OK with vacuum advance , it will pull more vacuum to help the motor idle with less throttle blade opening , and when you jump on the throttle , manifold vacuum with fall away , and it will run on the mechanical advance . you can run 22 advance and the vacuum advance could pulll it up to thirty
I amhaving a hard time with my Holley carb. How do you set you air/fuel mixture? Mine is at about 1 1/4 out and it just doens't seem right and when I hook up a vac. gauge the gauge doens't even move.
I have too much primary slot showing and I cant figure out how to reduce it. The idle speed screw is not touching and neither is the fast idle speed screw. What else can I do to make opening smaller? Like a square.
Rolando Paz id use a generic walmart brand after your fuel pump if your running a mechanical pump. if your upgrading your fuel system, i recommend running a return line. im finishing up my return line system here in the next two weeks and i plan to make a video over how i did it for cheap. return lines are very nice from eliminating minor vapor lock and leaner loss of power conditions in hot weather. number one thing for old car stalling.
This adjustment is also called the " cold idle cam adjustment" right? It is this adjustment that sets the cold idle-up when you 1st crank your engine right? Sorry man.. I have a 64 Fairlane and the previous owner half-ass installed the Holley 4 barrel and didn't bother even connecting the electric choke wire. He decided that it was just easier to slap the Holley carb on the engine then use the curb-idle to idle the whole engine up all the time to keep it running.. I am NOT a mechanic (and don't want to be one) but I am now forced to try to fix this problem myself (and Im getting pretty good at this I might say) lol .. I have my electric choke connected properly and my butterfly opens up to full as the engine warms up but unfortunately the engine doesnt idle UP when cold in order to keep it running. I have to sit in the car and tend the accelerator until the engine is warm enough to run on its own then its idled way too high of course.. I have the engine warm idle pretty much adjusted now. Now all I need to figure out is how to get the engine to idle-up when cold or (first started). Shit am I even making any sense? I am so sleepy as I am trying to research this shit. :( Thanks for any help you can give me man.
Hey there thuunderhead , how come no one tells us to WATCH how many turns or turn in my case were your idle transfer slots are correct ? Then you no 1 turn in from contact which is when most holleys are squared on t slot ,would not have to remove carb great info as always
This is a pretty old video at this point - but mostly because many different carbs have different curb idle screw assortments and throttle blade drillings. One way would be to hook a vacuum gauge to the ported port of a carb - there should be no vacuum at idle on that port, if there is, it's too much throttle
@@ThunderHead289 shows my computer illiteracy, bieng born end of 1960s we struggle some ,thanks for reply I realy enjoy your work and your hell of a tuner ,and that tip about the vaccum ,see I did not no that although I should ,thank you j
So I have the 4160 vac secondary. My idle mix adjustments have no effect. I set primaries to have the square. Can’t remember what secondaries are at (not with truck). So does the secondaries need to have the square too or should they be closed at idle?
Usually on a vacuum secondary, the adjustment is just below the transfer slots. Resist the urge to mess with that. When idle mix screws have no effect and the primaries are set to a square, either the choke is closing off a bit or the power valve is blown so it’s dropping in fuel
@@ThunderHead289 I know this a very old one, but always relevant to non EFI guys. A friend has a pristine 70 1/2 Z28 with it's original 4555 780 CFM carb. It's a vacuum secondary. You showed tuning a 4 corner carb? Before pulling the carb, I'd like to be prepared a little more. You just replied to a fella (Justin W) with vac secondaries and suggested he "resist the urge" to mess with the screw. His carb was a 4160 vac secondary. That leaves me confused now as to if it's ok to adjust this Holley 780 carb's idle speed as you showed in the video. You showed adjusting the primary slot to square, then not messing with it anymore, and instead, adjusting the secondary screw to obtain idle RPM........ I love that idea. It's so logical. I love how methodical you are. In another comment, someone mentioned a stand alone air bleed not related to the primary's or secondaries. Makes a guy want to drill and tap a new hole in the carb's baseplate and install an idle adjustment screw to make that possible. ........now where did I leave my drill bits? 😁
Love the sound of the car. Instead of a smooth sound idle, yours sounds amazing. Is that because of the cam? I want my 289 to sound like that. Please suggest cam, exhaust carb set up!
Look on youtube how the pros put the transfer slot where it needs to be. They start by drilling a .080 hole in each butterfly and go from there you will understand why the racers have done this for about 50 years tp get better response.
+Ben luck you can get everything adjusted quite close this way, you will end up with a proper throttle blsade position and an ignition timing where your engine wants to run. this is even better if you have an afr gauge like i do in my galaxie. then you can really dial in the engine. if you have to go to too much timing, your engine just needs more air and the secondary throttle blades can be open. im going to do a series right quick since im doing some head swap stuff where i set an engine up using these methods.
That was some good info on the idle set. You've got that Galaxie sounding really nice. Being a Ford man myself, I like to see and hear something besides what brand X has to offer. On the size of the Allen head screw, (actually called a "set screw"), it's a thread size #10-32 X 3/8" long. Any good hardware store should have them. If you have a problem accessing the screw from the bottom side once the carb is mounted, you can flip the screw around so that the head is on the top side. You'll need to shut the engine down and place the carb at open throttle and move the secondary arm to get the Allen wrench in place to make an adjustment, but it will be easier than having to remove the carb, that's for sure. One more thing that I've discovered on these Holley carbs is that sometimes this screw will have a sloppy fit. To fix this loose fit, you can wrap some Teflon thread sealing tape around the screw to take up the slack and keep the screw in place. I wouldn't use Lock-Tite because sometimes it works too well and you'll strip the Allen head portion of the screw when you try to make an adjustment.
This some of the best advice I've heard. I have a '83 F-250 w/ a 460 and Holley 4160 750 CFM, #73 primary jets and a #25 secondary metering plate @ 6,000 feet elevation. I could either get my carb to idle right and bog at part throttle or idle rich and run great but not both. I had never thought to use the secondaries for idle. Set the choke up, turned the idle screws out 1 1/2 turns from full seat, and left the transfer slots were he said. After it warmed up, my 460 was idling at about 1100 RPM so I turned the curb idle screw out 3/4 turn and now it idles at the proper 650-700 RPM. Pulls like no other and does 40-70 MPH pulls in fourth gear in about four seconds. Thanks, Thunderhead289!
Is you 460 Stock? I just put a 4150 750 on my 460 and am having the same issue. I was going to tackle the jets but am going to try this first.
@@briantarka6146 Port matched Cobra Jet heads and intake from a 429. I put a 4150 rear block on the carb so I could jet the rear. #72 in the front, #76 in the rear. 37° of total timing with a 15° vacuum advance. Everything else was the same from earlier.
When I first bought my car and rebuilt the 302, I watched this video and it ran real good. Long story short booms like to touch stuff and my carb has ran not so well recently. Just remembered this video and it is a legendary trick to tuning carbs! What a difference
I wish I had seen this 6 years ago! Great tip using the secondary to set idle. Never too late to learn something new!
I bought a car with a Holley 750/mechanical secondaries and your video really helped me get her running just right now. The carb was WAYYYY out. Thanks for the info. Nice and clear video
Good idea with the Allen screw for secondary adjustment. The way I went with that was just flip the secondaries adjustment screw over when carb is off motor so the flat slot is pointing up. It can then be accessible without hassle. Great video btw a lot of good pointers.
If your secondaries come on too late or to early is that the screw you would ajust to compensate for that ? I am switching from a 2bbl to a 4160 street warrior / classic Holly 600 i knew about the transfer slots from this vid awile back thanks 👍 Luke although not sure about how to ajust secondaries .
@@TheThirdWheel618 no there is a plastic cam that controls the ramp the throttle blades open at. You swap the plastic cams to get more aggressive or lazy throttle opening on mechanical carbs.
@@johnsnow1355 thanks now I seen a video where people were turning the carburetor upside down and there was like a little Allen screw at the secondaries and they were cracking that because they don't want to mess with the the slotted area in the primary section so by turning that little Allen screw I guess they open the secondaries a little and it caused the idle to go up without touching the idle screw at all.
I have that quick change diaphragm cap I'm assuming to adjust your wide open throttle it's controlled by the stiffness of the spring with them vacuum secondaries I probably would never need it but I bought that kit with the assorted Springs so if I wanted it to come on sooner I would just put the shorter weaker spring and if I wanted my secondaries to open later I would put the longer stiffer spring I'm guessing that's the way it works I doubt if I will ever need it because my engine is not that beefed up it just has a mild cam although I put an Edelbrock RPM on top of my 390 I'm not sure if the 600 CFM with a single feed gas inlet is going to be adequate I'm going to have to play around with it and find out.
Very good advise, optimum transfer slot exposure is .045, which results in the opening being open the same amount as the width, aka “Square”
Setting the curb idle with the Secondary throttle blade works great unless you have a really low manifold vacuum. Plus there’s other concerns when your dealing with a 4 corner idle carb in terms of balancing the carb, that’s when you can play with adding small holes in the throttle blades and/or use the Barry Grant idle ease feature. Both ways adding holes/idle ease were implemented to add idle air while maintaining the transfer slot function. Great Video! 👍👍👍
Great video man, good info. I just switched from Edelbrock to Holley and still learning all the different stuff you can adjust.
Very informative! Thanks, I just grabbed a used Holley and have been wanting to properly set the idle. This gives me a great place to start and adjust timing from there.
I used a 1 1/2" long screw an put a light film of silicone so it will stay where I left it for vibration control,i adjust it while it's running,works excellent!
I got a new 600 cfm Holley vac sec (1850) and put a metric M5x20 screw with hex head in it and used a nut to fix the adjustment. Works great.
I've thought about setting mine up like this. Just swapped my freshly built 327 with a 383 (i couldn't keep up 💨). I built it from scratch, 800 main body, billet aluminum hi flow metering blocks, base plate is tight with all new brass floats and everything. Worked awesome on my 327 then put it on my cj7 jeep 304 for a month then in on the stroker but i swapped the jets from 68 f 74 r to 73 f and 78 rear. Hasn't been right since, I've jetted down, checked for all sorts of possible air leak areas, swapped the power valve but nothing. It'll only idle at a very hi rmp but not in gear unless idled extremely high and if you try to idle it down It'll just die. The more you screw the idle air screws out the higher it idles but no matter what i try it i can't get it back to normal. Going to try your setup this weekend and see how it goes. Motor is .060 bore, scat 9000 3.75 crank/5.7 rod, flycut huge dome pistons, 1969 041X heads shaved to 62cc and running an elgin solid lift 30/30 duntov cam and lifters. Strange that the carb worked flawlessly on my 10.25:1 40 over 327 tight lash isky .465 solid grind and the jeep 304 with a small elgin .465 hyd. I had a 750 vacuum secondary on the 383 the 1st week i ran it and that carb worked good on it but jetted down and on the cj now. Do you think maybe it's throttle plate related, run 2 fuel filters and only run 110 octane turbo blue racing fuel at 12.5:1 compression
Your tutorial really helped me adjust my 670 holley. Thanks
Great suggestion on the allen key and allen screw. I have a 90 degree, low-profile screw driver set that I use to adjust this secondary throttle screw.
How much should the secondary blade be opened or is it variable based on the engine cam? Thanks
Any setting over .020 on the slot will cause a very rich idle. You can purchase the Billet base plate from Proform that has a screw on the top side of the secondary shaft for this adjustment. Its just like an idle screw. Lots of people dont want you drilling their primary shaft blades.
Great tip on keeping your high signal strength on your idle circuit with a big cam with really too much over lap, another top would be to incorporate a air bleed off in the center port which I believe Holley has already done.
You answered alot of questions for me thanks!
Awesome video about mechanical secondary and timing 👏
First accurate video iv watched, excellent
I took my Carter AFB off my 64 Buick Riviera to check this stuff. The primaries were not even close to square! I readjusted the floats and mounted it up and it works again!! Only thing is the high idle cam does not engage the idle screw and the choke isn't effective. Longer screw? BUT VERY COOL INFOMATION. Keep it up.
A lot of the racers with double pumpers adjust their transfer slots square, then they start out with a smalll drill and drill a hole in each primary butterfly, and possibly step up the drill size.
does this also wotk with a brawler quick fuel double pumper and manual choke and manual secondaries
my 600 Brawler doesnt have a adjustable primary throttle screw to adjust the transition slots? Only the secondary side does? Any tips for this setup?
My float level changes everytime I start the engine. Is this caused a bad needle and seat? Thank you
Hey man,
Getting ready to try tuning the carb on my truck I just finished touching every nut and bolt on. I got it to fire up and put around but it's really bad.
Had a question though, some of your videos contradict (or rather, use different methods) to setting idle. Sometimes you say use timing, in this you say use secondaries. Which would be the proper way? Are you still tuning your idle with the secondaries mainly? Should I aim for keeping those closed and trying to set idle with timing first, then if I need adjustment, use the secondaries?
Thanks a bunch
How do you adjust the primary transfer slot? I'm flooding the engine but have no idea how to set this without the idle speed screw.
With my big cam vortec everything square the motor won't even run..... No messing with timing will fix a motor that has under 5inch of vaccum at idle. Would drilling holes in the throttle plates be the way to go with mechanical secondary on a Holley brawler carb. Instead of messing with the secondary throttle blades to let in more air and increase the vacuum.
Just asked on another one of your vids, what does setting to square mean.
This explains it. Thanks
How do you adust the throttle blades to only have the little square part of the transfer slot showing?
You were a big help thanks .
Commenting only to compliment intro music !!
I have a 383 with a 700r4 and big cam... Idle gives 11 vacuum but once I put into drive it idles too low!!! I need it to be at 1400 to be able to drop it into drive to keep it alive... I was told to adjust the secondaries because of the big cam I have.... Any tips?
Juan, do you have vacuum advance on your distributor? If so, is your hose hooked up to straight manifold vacuum or metered vacuum (ie: off the metering block) ?? Vacuum advance should be hooked up to straight manifold vacuum for proper performance. Try that.
I have a 318 that I'm putting a 4 bbl street warrior 600 cfm holley carb on. I have no idea what I'm doing but maybe you can help
I've recently started learning about these and how to really set up a holley, as I've always used a summit or edelbrock which seem to be fine already when I get them. I have an almost stock 390 FE with an "RV" cam that just has a little more lift/duration than stock. I have a summit distributor and where it's curved right now I need like 15° BTDC initial timing to get 36° total, any if I move the initial down much it really bogs and loses power in the low end and it SEEMS to want more than 15.
The problem, my idle is too high. I took the carb off and set the secondary and primary blades so I have just the square of the transfer slow showing. I set the curb idle screw so that it was basically backed out all the way when you could see just the square. Now when I back the screw out all the way with the engine running it's idling too high.
Long comment, but is it ok to have less than a square of the transition slot showing? Or even none of it? Basically when I set it by eye with the carb off and I have a square, put it on, it idles too high.
What size grub screw did you use so I don't have to pull it apart before I start please.
Its a 10-32 thread
What size is the allen screw? I'll have to give this a try. I should be able to have less throttle plate opening since I have a smaller cam with higher vacuum as well.
1972FordF150 i dont remember the exact size and i dont think i even looked. i pulled the screw out of my carb and compared it against others by putting the threads together. really makes a big difference when you get full transfer slot usage on the primary size. really has cleaned up that lean stumble a lot.
How do you do this on a 2barrel Holley carburetor? you can also drill a small hole in the throttle plate to get the same results.
Very good on setup of Idle circuit. Why do some guys drill holes into the throttle blades?
Will this work on dual carb tunnel ram? Sideways mount????
Nice video. Good info, will give it a try when it's time to assemble my rebuild engine. thx
I was hoping I could pick your brain on a few questions I have
Very good video, thanks
Ive heard time and time again about adjusting the transfer slot exposure even on new carbs. What doesn't make sense to me is if it's so important, why isn't it set "correctly" from the factory right out of the box? I ask this because the new carb i just bought didnt have the transfer slots setup like Ive seen several content creators suggest.
It usually is. Then some meth head starts winging the curb idle screw all over.
Edelbrock made a new carb that uses a bypass air valve to adjust idle speed - the way it should have been done from the start.
@@ThunderHead289 I appreciate ur reply, Luke, Thanks. The next question that comes to mind tho is if u shouldn't adjust idle with the curb idle screw....why is it there as an adjustment in the 1st place? As you can probably surmise, I'm no carb guru but I'm trying to overcome my ignorance. And yes, Ive got a carb (Street Demon 625) that's giving me trouble getting it setup on my '72 Camper Special. I'm not finding any adjustment for secondaries that will allow me to alter idle speed and that's not surprising as a Street Demon is a different design from the Holley you used as an example. So I'm still kind of swimming in circles looking for answers to a list of questions like why I lost 20% fuel mileage just by bolting this carb on. And why after the engine is warmed up completely and then shut down, 5 mins later it wont start etc etc....SMH.
good idea with the allen key.
Regarding the lawnmower fix(with dirt in the fuel screen), can you make a video that shows how to just take off the gas tank to clean fuel lines, screen, etc. on the exact same Briggs and Stratton engine model that you already have videos of? That would be flipping awesome if ya could! I need to do the exact same thing you did, but I don't want to mess with coil and such...Thanks so much if you do.
Hey enjoying your videos and learning a lot, thank you. I got a vacuum gauge, put in on port and am pulling 5” of vacuum at idle, so i backed off the idle til the vacuum went down to zero and then added timing til it idled decent but it was then at 30 deg. So I backed the timing down to 22 which was as low as i could and still keep it running (about 600 rpm). I was wondering if you had any advice for me. Thanks
I have a Holley 4160, big block Mopar. Mostly stock. Mild cam
run a vacuum advance can if you dont . 30 degrees at idle is OK with vacuum advance , it will pull more vacuum to help the motor idle with less throttle blade opening , and when you jump on the throttle , manifold vacuum with fall away , and it will run on the mechanical advance . you can run 22 advance and the vacuum advance could pulll it up to thirty
I amhaving a hard time with my Holley carb. How do you set you air/fuel mixture? Mine is at about 1 1/4 out and it just doens't seem right and when I hook up a vac. gauge the gauge doens't even move.
Go to the recent uploads playlist on my my pre and go through the bench setting and first start tuning vids I literally just made a week ago.
What holley is it? 2 barrels in my experience you have to hook the vac gauge to the pcv port, not where the vacuum for the distributor goes.
I have too much primary slot showing and I cant figure out how to reduce it. The idle speed screw is not touching and neither is the fast idle speed screw. What else can I do to make opening smaller? Like a square.
John Evans drill a very small hole in each primary butterfly.
@ 6:12 is that a wood carb spacer?
I got a high cam and I get. Burning eye stinky exhaust. Is it the carb rich or..juzt a HighCam and can't do anything. To make better
So how do you set idle on a 350 2 barrel with no secondary?
Can this adjustment be made with the Carb installed ?
But if the tranfer slots are squared when set and the butterflies are closed, were will the motor suck Air from???..
Your butt
What exhaust are you running on your car?
Good info, thanks.
Going to overhaul my fuel system, new lines, new tank. I've got a 302, what inline fuel filter would you recommend
Rolando Paz id use a generic walmart brand after your fuel pump if your running a mechanical pump. if your upgrading your fuel system, i recommend running a return line. im finishing up my return line system here in the next two weeks and i plan to make a video over how i did it for cheap. return lines are very nice from eliminating minor vapor lock and leaner loss of power conditions in hot weather. number one thing for old car stalling.
This adjustment is also called the " cold idle cam adjustment" right? It is this adjustment that sets the cold idle-up when you 1st crank your engine right? Sorry man.. I have a 64 Fairlane and the previous owner half-ass installed the Holley 4 barrel and didn't bother even connecting the electric choke wire. He decided that it was just easier to slap the Holley carb on the engine then use the curb-idle to idle the whole engine up all the time to keep it running.. I am NOT a mechanic (and don't want to be one) but I am now forced to try to fix this problem myself (and Im getting pretty good at this I might say) lol .. I have my electric choke connected properly and my butterfly opens up to full as the engine warms up but unfortunately the engine doesnt idle UP when cold in order to keep it running. I have to sit in the car and tend the accelerator until the engine is warm enough to run on its own then its idled way too high of course.. I have the engine warm idle pretty much adjusted now. Now all I need to figure out is how to get the engine to idle-up when cold or (first started). Shit am I even making any sense? I am so sleepy as I am trying to research this shit. :( Thanks for any help you can give me man.
Can you do this on an Autolite 4100?
I know this is old but is that a piece of wood for a spacer? Looks like a wood grain on the side of it.
Phenolic spacer , B&B sold them they don't hold heat
Hey there thuunderhead , how come no one tells us to WATCH how many turns or turn in my case were your idle transfer slots are correct ? Then you no 1 turn in from contact which is when most holleys are squared on t slot ,would not have to remove carb great info as always
This is a pretty old video at this point - but mostly because many different carbs have different curb idle screw assortments and throttle blade drillings. One way would be to hook a vacuum gauge to the ported port of a carb - there should be no vacuum at idle on that port, if there is, it's too much throttle
@@ThunderHead289 shows my computer illiteracy, bieng born end of 1960s we struggle some ,thanks for reply I realy enjoy your work and your hell of a tuner ,and that tip about the vaccum ,see I did not no that although I should ,thank you j
Great idea
So I have the 4160 vac secondary. My idle mix adjustments have no effect. I set primaries to have the square. Can’t remember what secondaries are at (not with truck). So does the secondaries need to have the square too or should they be closed at idle?
Usually on a vacuum secondary, the adjustment is just below the transfer slots. Resist the urge to mess with that. When idle mix screws have no effect and the primaries are set to a square, either the choke is closing off a bit or the power valve is blown so it’s dropping in fuel
@@ThunderHead289 I know this a very old one, but always relevant to non EFI guys.
A friend has a pristine 70 1/2 Z28 with it's original 4555 780 CFM carb. It's a vacuum secondary.
You showed tuning a 4 corner carb?
Before pulling the carb, I'd like to be prepared a little more.
You just replied to a fella (Justin W) with vac secondaries and suggested he "resist the urge" to mess with the screw. His carb was a 4160 vac secondary.
That leaves me confused now as to if it's ok to adjust this Holley 780 carb's idle speed as you showed in the video.
You showed adjusting the primary slot to square, then not messing with it anymore, and instead, adjusting the secondary screw to obtain idle RPM........ I love that idea. It's so logical.
I love how methodical you are.
In another comment, someone mentioned a stand alone air bleed not related to the primary's or secondaries.
Makes a guy want to drill and tap a new hole in the carb's baseplate and install an idle adjustment screw to make that possible.
........now where did I leave my drill bits? 😁
Love the sound of the car. Instead of a smooth sound idle, yours sounds amazing. Is that because of the cam?
I want my 289 to sound like that. Please suggest cam, exhaust carb set up!
myfoodexperiments probably can but idle has a play in it to if your idle is higher you don’t hear a cam and mufflers make a huge difference
will the secondary idle adjustment effect vacuum actuator? ie if closed to far the vacuum diaphragm won't open the secondaries
Love it
This is probably why I'm rich at idle
What if u cant get idle low enough
Excellent, excellent video, though you did tap the gold butterflies in the beginning of the video and said they were the primaries
Lol that's hilarious if I did that
do u set idle air mix in gear for automatic as holley recommends or 750 rpm in park is okay?
800 900 or so in park is probably fine.
YES-SIR!!! Your motor sounds STRONG!
What lift/intake duration does the cam have?
What causes it to pop on Acceleration
allmond944 being too lean
Use a screw with knob on the end
gold
Song name
Did you ever find out the song name??
Eric Clapton - Layla
@Dennis Massengill Neat.
Can I have your Galaxie? Thank you in advance!
lol. not too many people would like to have the rat trap
I dont think I would tell anyone to change there idle by adjusting you timing lol
Then you are lost
@@ThunderHead289 well I cant be lost the car likes 44deg timing my idle would be just a little hi
Great information. Just invest in some lighting.
Check my more recent carb stuff out.
Look on youtube how the pros put the transfer slot where it needs to be. They start by drilling a .080 hole in each butterfly and go from there you will understand why the racers have done this for about 50 years tp get better response.
Yeah DO NOT set your idle by adjusting your timing
+Ben luck you can get everything adjusted quite close this way, you will end up with a proper throttle blsade position and an ignition timing where your engine wants to run. this is even better if you have an afr gauge like i do in my galaxie. then you can really dial in the engine. if you have to go to too much timing, your engine just needs more air and the secondary throttle blades can be open. im going to do a series right quick since im doing some head swap stuff where i set an engine up using these methods.
So on a mechanical secondary it need to be square off like the front? Just a little square with transfer slot?
what size holley carb do you have on this post