500 CADILLAC MODS (pt2)-HOLLEY vs Q-JET
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- Опубліковано 30 вер 2024
- PORTED & EARLY HEADS, BIGGER CAM & CARB COMPARO! FULL DYNO RESULTS! WHICH CARB DOES THE BIG CADDY LIKE MORE? WHO HAS ALWAYS WANTED TO PUT EARLY (SMALL-CHAMBER, HI COMPRESSION) HEADS ON A LATE-MODEL (MEANING MID 70s) 500 CAR MOTOR? HOW MUCH DOES IT INCREASE COMPRESSION AND POWER? WHAT ABOUT PORTED LOW-COMPRESSION HEADS OR A WILDER CAM?
Q-JET !!!!!!! they work great when you know how to work on them just ask people who run super stock and stock class that have to use them. Ford even used the Q-Jet on the 1970-71 429CJ.
7.73 on a quadrajet
I always preferred a Q-jet for daily driver/street motors, specifically because of the barrel setup. The primaries being a little undersized limit fuel use during cruising, saving gas. Hell, in my '82 Trans Am, I leaned it out a bit and could get 25mpg if I kept my foot off the gas, with an idle RPM of around 600.
But those massive secondaries, man - open them up, and just about any V8 with one just ROARS, lol.
Yes, and they won't burn your car down like a Holley.
Holleys are famous for running over and starting a gas fire.
They do have a sound
I always ran Holleys on my hot rods back in the day. Now that I know better, I wish I still had some of those cars.
I build Qjets and Holleys, both for gas and E85/E100, I like them both a lot. I can coax power out of the Holley easier, but they don't have the drivability of the Qjet. If you know what you're doing, its not hard to get Holley power from a Qjet, it just takes a little more trial and error. The Holley is a lot easier to work on, since you don't need to remove the top like a Qjet. My Qjets do a lot better on gas mileage and still make power on par with the Holleys. Doesn't matter if its a 600 vacuum secondary or an 850 double pumper, I can get that power from a Qjet and still drive it like a daily driver.
On E85 its easier to get enough fuel flow and a rich enough AFR with a Holley than a Qjet, the Qjet needs considerably more work, but man do they drive nice on the vodka. 13:1 with iron heads is daily driver stuff on E85, even with a cam that makes a ton of cylinder pressure from idle to 5500.. No need to bleed it off with a bunch of overlap, just throw the vodka at it. Rich is more power on ethanol, if you run it too lean it will still run, just make less power. Stoich isn't where best power happens to be on vodka fuel. Where best power is will depend greatly on the engine, runner length, velocity, chamber shape, cam timing.. all of that makes a big difference on how much fuel an engine wants to make the most power.
Would a "6 tube top" power enrichment system on. Some Q-jets be an advantage running E85. And besides the acceleration pump cup, brass float and the biggest needle an seat ,bigger jets an smaller metering rods is ther anything else you have to do to run E85 using a Q-jet ?
@@dondotterer24 I haven't found any accel pump cups made since 1983 that didn't work. The blue ones for sure work and last a long time. That info came from my testing and passing it on to Cliff.
The blue ones are easy to identify, but the only problem I had was with a kit I had sitting around since the late 80s that was made between '79 and '82. I haven't found any others with cup problems. Even when they sit for a year or two on the shelf, they still work fine when I put them back on the car.
No problems with gaskets, parts, or anything else. I soaked one in a bucket of E85, open to the atmosphere for an entire year, then I drilled it, put throttle shaft bushings in, and ran it on E85/E100 for 8 years. It was really clean.
There is an accel pump circuit restriction in the top cover of some Qjets that needs to be removed, easy enough to do. Sometimes you need to open the orifices as well.
Haven't found a problem with brass or foam floats, they all work, but the level is different than gas, its a trial and error thing per model to know where to set it. Ethanol has a different specific gravity so the float sits higher in it.
Nobody makes jets large enough for E85, so you just drill some from the bottom, how big varies by model. Drill them, use a check ball to make a new radius in the jet orifice and you're good. The metering rods can be the same ones if you get the jets right, but you want to enrich both front and rear. Start at 25% larger orifices and see where it runs, then sneak up on it by going slightly larger until you get it right.
The secondary side is where it gets challenging, .Sometimes you can drill the orifice, sometimes you need to make small rods, its one of those trial and error things where you need a wideband to see where its running.
Idle screw passages get opened to .100-.110, I like the windowed inlets and if I get a solid one I drill it twice in an X pattern where the window is on others, and they get drilled to .152, much larger and the needle seat won't seal, but sometimes you can go larger if the needle is big enough.
Anything you can do to make it run richer will help, because getting one to 7.5:1 AFR where E85 makes best power is hard to achieve. A small float helps if you can get one, and if it has the plastic plug on the passenger side under the 'hat' you can remove it and add bowl volume... provided it doesn't have the port under the plug drilled.
Getting 8.8:1 to 9.5:1 where it gets the best mileage is relatively easy.
If you drill the boosters it will pick up a lot of power but it will also use A LOT MORE fuel. My smallest bit is too big, and its like .027 or so. Might work better to 'file' on it with a torch cleaner to sneak up on the target AFR.
Every model is slightly different, some need more work in areas than others, it really varies. So it takes me a while to get it all figured out, lots of driving, testing, and watching the wide band.
If you have Cliff's book, its a slightly larger version of his 'race' recipe, with a couple extra changes like the accel passage. If you don't know how Qjets function, you can really screw one up.
@@SweatyFatGuy Yep. My last one I bought from you. And have told many people to buy everything they need from you. And explained why. And I will do the same. BTW what do you think of what they done during the test? Do you think they should of changed the secondary throttle blade angle when they put it on the aluminum intake?
@@SweatyFatGuy sorry I thought you were cliff I didn't read. But if you will pass it on to Cliff please.
Thanks for the time and alot of information! I do have Cliffs book. My friend Ken Shawver that used to run super stock has run one even without the primary metering rods.
"Where's the Q'jet fans?"
Here's one!
You have to know that after 40+ years of tuning you learn things.
At wide open throttle, the 750 and 800cfm versions of the Q'jet equaled every other carb of the same flow rating.
Where the Rochester really shined is at everything below wide open. With interchangeable jets, metering rods, rod hangers, part throttle "power springs" for the primary metering rods, adjustable acc. pump shot, and vacuum and spring adjustable air flappers above the secondary throttle plates the Q jet is tunable over the entire throttle position range of throttle positions between idle and wide open throttle.
There's absolutely no question the Holleys are much easier to tune, but the drivability of the Holley can't come close to the Q jet.
When accurate fuel mixture anywhere below wide open throttle matters just as much, it's the Rochester hands down.
Want better? You have to be willing to learn how to tune for it.
Holley carbs are like Chevy engines. They're everywhere, and they allow kids with no experience to build power easily. Q-jets are a grown man's tinker toy. All the power and smoothness you'll ever need or want, but ya gotta be smart and experienced enough to tune them in correctly.
Q Jet is a great carb. No idea why it gets the disrespect it gets. You have a great carb for cruising with that little 2 barrel then step on the loud peddle and the the toilet bowl opens up and it’s time to fly.
Best carburetor ever build
All you guys with your old school black magic. Carbs are dead. You know how hard it is to find a carb tuner now.. they are either dead or in a old folks home.
I am 34 and could tune a carb blindfolded. Carbs aren't dead, plenty of race cars and street rods atill run them.
Nobody's mentioned yet that a .060 over Cad 500 is 514. Just saying.
But it's freaky listening to a dyno pull starting at 2000 and ending at 5500. The engine never sounds stressed.
Id like to see 8 o2 sensors with a q jet vs Holley to see if the q jet has distribution issues with big and little butterfly's.
You know that's a damn good idea I second that
That would be awesome! That and also swap out different intakes
I recall reading somewhere that the secondary throttle plates are designed to stop just short of 90* to help direct airflow into the rear cylinders,on certain application. Maybe it was in Cliff Ruggles book?
that would be cool
@ my qjet would suck the bowl dry on a 402ci chevy
Richard, can you show and give more details on the head modifications, flow numbers, etc?
Built a very similar 500 for a military M715 4x4 20+ years ago. Mine had forged JE "D shape dished" pistons for 10 to 1 compression. I used Oldsmobile 425 forged rods (bolt in with custom pistons). I had a massive amount of time in the early 76cc heads. Machined for 2.19 and 1.77 Pontiac valves, un-shrouded chambers, ported through the push rod reliefs and patched with epoxy. A 238 @ .050 custom ground cam. Started with a custom welded Ford 460 intake W/ spacers, then a fabricated sheet metal cross ram intake, but switched to the Edelbrock when it came out.
Never put it on the dyno, but I estimated around 525 HP and 550 torque. It was happy to rev to 6000 RPM although it was done pulling hard by 5500. It was an overpowered scary beast off roading in that old truck that needed suspension upgrades to match the power.
The truck: drive.google.com/file/d/1Dx9uIzrUbfzyeLZUkOE0zS5VVnKBFRCU/view?usp=sharing
I don't have flow numbers unfortunately
Awesome truck
The sound of vacuum secondaries opening up under power on a qjet will never be forgotten ❤️ unfortunately I only remember Holley for engine fires
Cuz they leak like a Harley!
I once counted 17 places they could leak and probably missed a few.
There's no vacuum secondaries on a quarter jet. They're a mechanical secondary with an air valve, a spring-loaded air valve to keep the vacuole up so it pulls air fuel and is air valve opens. It actually takes the shape of a Venturi
Test matching carbs. Its a no brainer that a 950 CFM Holley is going to out perform a 800 CFM Qjet. If you had them even 800 vs 800 Qjet they would likely be about the same if not the Qjet would at least slightly outperform the Holley.
You cannot beat a properly set up Qjet on the street. Their throttle response is amazing. But if youre comparing a Qjet to a Holley, shouldn't they be the same size carb? I mean youre comparing an 800cfm carb to a 950cfm carb. That kind takes the "which is better" arguement away and replaces it with "how much airflow does this engine need".
It's simple Holley is a brilliant toilet..if you need to support big cubes it's an ok choice..hell look at my avatar..those are 1100 cfm dominators..the Rochester on the other hand is a very simple to tune efficient variable venturi (up to around 800 cfm) carburetor..
Have any Q-Jet guys tried using a Model #17085213 from a 1985-88 or so one ton Chevy pickup? This is a non-electronic carb with more adjustments than almost any other Q-jet. Without pulling the air horn you can adjust both upper limit and lower limit travel on the primary metering rods. There is also an adjustable air bleed in the secondary circuit, under a brass plug on the back of the carb. There is also the usual spring tension adjustment on the secondary air valve as well as secondary metering rod and hanger adjustments. So this carb can be fine tuned much quicker and easier than a Holley!
Hey Rich,Thanks for excellent video .I would rebuild the Q.jet carb during my coffee break and run only part throttle primaries during work week and wide open on weekend.Got the best of both worlds with Q.jet.
It's amazing the horsepower gains that the basically stock, original carburetor can support. I can't think of any other stock carbureted engine (besides other q-jet engines) where you can double the horsepower on the original carb.
Thermoquad comes to mind for one example. Some thermoquads were 1000cfm.
@@wildrosegarage4208 Thermoquads were originally designed as "performance" Qjet replacements.
Awesome video! Love that when something doesn't go quite right you own it and figure it out and fix it. So much knowledge being shared on this channel that otherwise is in danger of being forgotten and lost in the next few years. Great job,sir!
Thank you for adding this insight.
I agree the reality of the process is not lost here .rich is the most detailed and easy to understand
I'll watch anything he does. Ty rich!
Back in the 80's I could make a Q-Jet perform better than a Holley. I had guys give me their Holley because they would go faster with my Q-Jets. I don't know if that would be possible nowadays because Holley has got so much better. And I have not touched a carb in many years.....
Q-jet needs me to tune it, LOL. Power piston spring, primary jets and rods plus secondary rods and hanger. All need changing.
This really makes me want to go with the old school Cadillac swap instead of the LS swap in my 84 El Camino.
Cad 500 parts dot com has the mounts. Bolts right into g bodies. I've been wanting a cad powered g body for years.
Maximum Torque Specialties in MA had a kit to drop a 1970 500 into a Malibu of that era. They ran 11's without modifying the 400 hp engine. Before the 502 Chevy was cheap enough to buy used at swap meets, a Cad was the secret for Chevy/GMC pickup trucks. Buy one at the junkyard, get the 425 single plane intake, Chevy or Ford 429 header tubes welded onto an aftermarket flange, and don't worry about the low compression--you had a beast for towing, with diesel like torque off idle.
Nowadays, of course, you can pick up a motorhome 454, it won't be sludged with motoroil like a 1970's engine, and make decent power that shocks the LS fanbois who think anything older than them must suck.
Q.m
I get the feeling that needs to be made into a shirt.... "Who wants to see a bigger cam shaft?"
Yes please
"Who wants to see my bigger camshaft?"
Who wants to see my camshaft with longer duration.
@@axleratio this one wins!! Hands down. Lol
lol - SIZE IS everything...
*PLEASE DO A 403 OLDS!!* I have a 79 trans am and would love for you to do a 403 and Big Bang it I mean come on it’s the biggest small block! 😁
Olds stuff (even more than Pontiac) is rarely found, at least valuable/accurate content. Bill Travato did a bada$$ turbo Olds from a 350 diesel block. If anyone could pull it off its Richard. It'd make a Great addition in "the other guys" series though
I do like 6.6L Trans Ams
@@robertmacpeek424 Trovato also ran his Starfire with Nitrous Oxide I believe .. It went high 7s IIRC..
@@richardholdener1727 I doubt that anyone cares but I put a 403 olds in my 69 cutlass and compared it to the 350 olds that came out of it on my channel
holley is a great replacement carb,fairly inexspensive and a little more flow and tuneabilty.[easier to tune].anybody who got to tune a q-jet or weber or ect for there cars emission or performance back in the 70's thru 90's had to learn how to bend rods and drill out carb bodies,not needed on hollies.test will be close but give it to holly.took a little tweaking but got a 71-buick 455 riv to pass 80's emission's.keep up the good work.
Love it. What a great content.
Your 3-4% power increase rule per point of CR seems to apply in this case as well. Increased CR by 3 points increased power around 10%.
Q jet all the way ! Ben spankin holleys for 40 years . I think the carb cfm should be the same for a test . Ditch the 950 cfm holley . Get a 800 cfm so ther the same ! I get 3 , 4 more miles to the gallon with my q jets than the holley guys and beat them more often than not when race . One example a buddy did a 400 bb ford . Rv cam headers holley . Hes in a 79 short bed . Im in a 79 blazer . Stock 350 . Q jet n headers . Even my buddy agreed i got him by at least 12 truck lengths . Spreadbore power all the way !
My experience with the Quetta is size for size cfm for cfm the q jet makes impressive power with a knowledgeable tuner. The 1971 Pontiac 455 Ho I believe used a 750 cfm Q jet. Most significant problem I experienced was getting a inlet needle and seat large enough to provide enough fuel for the carb to work properly (not run out of fuel). Properly tuned they, the Q jet, works great. enjoyed the test. Thanks for sharing.
That motor loved that compression increase! Wonder if that could be run conservatively with 93 octane gas!
put it on e85
That's a big maybe. You might have to cut some timing but the gain is power the 99% of the time you're not at wot will be worth it. It will also idle way better.
If it was put together for this and had things like positive deck pistons, 035 or less quench clearance and polished chambers and piston tops it would probably run no problem with a 160° thermostat. At the drags or even doing pulls on the street it would be fine. If you put it in a one ton pickup and tried to pull a trailer up a grade for miles, you'll run into issues pretty fast. Hot rod built an 11 to one all iron small block fifteen years ago that didn't pick up any power with fuel above 87 octane. It can be done.
👍
I doubt i tried 11 to 1 on an iron headed engine and that was pushing it
500+ lb.ft. Torque from 2000-5600 rpm!!! Umm,... YES PLEASE! That’s as much or more torque than most turbo diesels (5.9, 6.0, 6.4, 6.6) from the 2000’s and it’s over a much larger rpm range. That motor would be a beast in about anything you could put it in.
Hi,
Need 'O2 ' sensors in each exhaust port . on the ' Q-JET , Let the secondary butterflies open past 90* decrees to put more fuel to the front
Cylinders . Check fuel pressure @ the fuel inlet on the Q-JET To Prevent A lean condition .
The q jet was always a junk carb. It has ridicules uneven fuel delivery, uneven air delivery. A d dumps raw fuel into the motor from no rear boosters.
Annular discharge Holly's rule. Q jets have tubes in the secondaries for boosters.......lol
The rear bolt on the intake is awesome fun. No really the caddy motor is the best.
Favorite part of this site. Absolutely love the Other Guys content!
I have a 72 caddy hearse with a 472 and I have two 500 caddy’s in my shop I’m gunna build one and put it in a square body Chevy truck
My grandfather had 12 of these 472 and 500 ci caddies. You know they only weigh 75lbs more than a sbc.
This is motor I want to put in a 32 ford . Tired of seeing the small blocks . A 450 hp 550 torque cad motor in a 32 would do the job nice . I would guess 11 second quarter mile times?
Just put it in Drive and stab the gas.......LOL
its a wide engine to toss in that engine bay (in the day, folks preferred the Buick nailhead on Model A's due to the narrow width) and there's the length of the front water/oil pump and filter, but you'll certainly want highway gears, maybe even a Buick two speed to kill launch torque. Otherwise you'll do 11 seconds b/c you're blowing the tires away at launch.
Of course, a Ford in a Ford isn't a bad deal, either. A low deck Windsor is nice and light, or a crate 427 cid tall deck Windsor would have all that torque you want and run EFI cheaply, too.
Haha try like 9s 450 horse and 550 ft lbs of torque will rocket anything especially since nearly 500ft lbs comes in at 2k rpm
@@tedteddy2293 that's what made them such a great engine in a brick nosed Chevy pickup you used to pick up cheap. All that room in the engine compartment for 'em with diesel-like torque. And Chevy BB headers for those slabside trucks could be cut to fit the Caddy.
Qjets are a great carb for everyday driving. If it wasn't for the heak soak problem, they'd be the perfect street carb.
This motor looks like it can be a budget build competitor to the Chevy 502 BB?? The Cadillac bolts onto a TH 400 ?
No way
Yup. I switched from a TH400 to a 700r4 for that additional gear.
They came with a TH400 from the factory, just with an extremely long (somewhere in the 14" range) tailshaft. Nice part is BOP TH400s are alot easier to come by for cheap than chevy versions.
@@calebdean2440 TH400 and TH425.
Not a competitor.. a 454 has 92% of the CID of a 500 cad and zillions more head choices at the junkyard. 454 + junkyard heads + cam over 500 cad every day of the week.. much cheaper n better.
I’m ignoring all the comments and say the Cadillac likes the holly best above 4000. Just a guess.
Very cool!!
Love hearing the engine's run on the dyno!
Thanks Richard!
Welcome to the Richard Holdner EDM dance party! Oh and Richard will be doing some Dyno testing as well.
I got a test for you. No cats vs regular cats vs high flow cats.
Everyone keeps talking about potential to make good and equal peak power with both carbs but the q-jet is better for millage and low speed driveability but what about a spread bore holly?
Those small chamber heads didnt have piston to valve clearance issues with the 75 shortblocks pistons?
From what I have read Qjets are only good for about 500 hp do lack of fuel flow through the needle and seat. This is do to to the small float. The needle and seat size is the limiting factor.
You should contact Justin minahan he runs a Nostalgia dragster in the west coast Nostalgia drag Association known as ANRA. Copper Cadillac, its a bad ass ride
When u r in the middle of nowhere a mechanical repair is easy w a Q J
Try McGivring a computer F l
Can't use bailing wire and duct tape with F I
I love the QJet. I guess because it took me to school.lol. I had to learn so much just to understand the basic function. After a buying a used junker QJet. Cliff Ruggles book and hours at the kitchen table,don't tell my wife. I ordered Cliffs rebuild kit. Dial in the APT and larger down tubes. The Qjet is a wonderful carb now. My 780 Holley VS with 79/84 runs well but doesn't have the throttle response like the QJet. But the Holly seems to fell stronger from 4k to 5200rpm. But that just might be me idn
Agreed. Quadrajet has those nice snappy "small" primaries. Makes them great on the street when just cruising around at part throttle and then mashing your foot to the floor. It's really my favorite out of the Factory OEM carbs by far. Sure it's more difficult to take apart, service, etc. but that's because it designed really to just be left alone and ran on a factory stock engine. But they are capable of greatness. Especially in offroad applications.
Q jets are trash. The quadrabog was the reason no one buys american cars anymore....
@@thefinalroman While in theory you may have had an argument given the small cross section singling out SMOG era cars of the mid-70's to late 80's combined with the built in obsolescence factor from the same era designed to promote continual refresh the quadrajet was around long before that time as a very reliable carb used on a large percentage of the most powerful and respected cars that US auto manufacturers ever made which are still highly sought after to this day. In regards to "nobody buys american cars anymore" well.. Worldwide automotive sales figures would tend to disagree with that with combined totals of between 15 million and 17 million units annually over the past 7 years.
@@thefinalroman quadrabog,-dog,-junk,-smog blah blah blah blah!!! Ive heard it all. Don't bash it due to lack of patience and understanding on your part. That's simply elementary my dear Watson. Elementary.
@@pjmccoy4216 Lol those carbs were trash. Forf,Chrysler,Honda,Toyota had good carbs but those quadrabog junks never started ran like crap leaked gas stalled out and even when they worked the 305 dog motor with a quadrajunk barely got 10mpg. People want a car that runs not a piece of shit you can polish all day and never get out of the garage....
Quadrajet had a lot of cfm for a stock carb. Depends what holley you use.
That’s like diesel numbers on torque. That thing would tow really good.
Y'all keep running Chevy qjets
Need to run a qjet meant for a Cadillac. All qjets were make model year and application specific.
My dad had a 79 camaro that had a broken choke on the carb. I bough an 800 Qjet at a swap meet, tracked down the build tag to a 455 olds. He didn't think it worked as good until we went to the strip. Kind of wish I had a wideband.
If its correctly built the original application doesn't matter unless it's for a buick, then there may be manifold clearance issues
A properly sized and tuned Q-jet will make the same power as a Holley while being more drivable and get better mileage.
Love the Cad 500 motor! Years .....many, ago, I put a 500 into a 1968 Riviera. All stock and not fast. But would do burnouts from Hell!!!!!
Did you use a 425 belly button pan?
Why the hell do you have a mask on?
engine has enough torque I would run a high rise intake and a big camshaft and lose down low but gain hp up top how much does this engine weigh power vs weight
All that extra compression needs is more camshaft to bleed off the extra pressure. Either that or change to E85 or methanol.
The best anything I’ve watched during this quarantine I’m so excited with these videos Cadillac!
Glad you like them!
Qjets get MUCH better fuel economy than holleys. I'll take that trade off any day!!
Qjet vs Holley. Well what's the sound of a Qjet worth to you??? 5 hp???
Man that caddy made stupid Torque power and the horsepower was great as well for flat tapped cam
Stupid test. I already know the answer from 35 years ago
I’ve worked on most all carburetors and modified ones , I’ll take the Quadrajet every time.! Less parts and it can be taken apart while it’s still mounted on the engine… never been a Holly fan to many issues with them ( but they do have a broader cfm flow ) plus when on a 4x4 in various terrain they cut out unless you buy the float springs which will fail after a period of time.. Q-Jet all the way.!!!!
Love it! The caddy is pretty strong. I actually expected it to be more torque biased than the Buick but then again these are ported heads versus non so that makes a difference.
I’m a Q-Jet fanatic. It makes my blood boil when I hear some knuckle-dragging wanna-be racer run their mouth saying Holley/Quick fuel/whatever make more power 🙄. The ONLY time a Holley or whatever will make more power is if the engine it’s bolted onto needs more airflow than a Q-Jet can provide. Assuming both carbs are properly calibrated, they should be equal. Where a Q-Jet shines is the part throttle drivability. The things that make the grease monkeys bitch about the Q-Jet being “too complicated” is what makes it so versatile and efficient.
10/4
WHAT ARE YOU YELLING AT??!!?? Yowza, might be time to ease up on the caffeine just a bit.
crisp and clean and no caffeine
*Why do you guys always work in slow motion?*
Can't ya speed it up?
Blower?
Big fan of the Q jet. The problem with the q-jet is the aftermarket doesn't care for it. They think it's difficult and hard to work on. So intake manifold companies don't bother to make much over a 5500 RPM manifold for them
Very cool! I should make a response video to this! You always put up awesome content!
You can use a 10.25 1 or 10.5 1 motor. They aren't all 8.5.1
As for the jeep
It has a big quad holly
All needs rebuilt
At some point. Could you show a comparison of a 248 cam on a 350 to this 500? In relation, tbis 500 is acting like a 350 with a 220 cam.!!!
On the dyno it's really hard to quantify it. Youre only looking at power at wide open throttle. If you take a new Ls2 crate engine and put the biggest cam you can fit to the valves and take another an put the highest flowing largest port heads on it, they will have similar power curves. When you start to compare these at part throttle you will get some substantial differences. If the factory or ported heads had huge port volumes, it would really cripple the low end torque with the bigger camshaft especially at part throttle.
do you think biggest head with a stock cam will make as much as the biggest cam (p-V) with a stock head?
@@richardholdener1727 that depends. An ls2 will gain somewhere north of 90hp with a max effort cam swap, and a stock cammed ls2 will gain about 45 with max effort heads. If you do the same comparison on an ls3 it's not even close, the factory heads are too good and max effort porting doesn't do too much. What if you had an L78, it's got pretty aggressive cam timing and pretty good heads but the huge dome on the piston might cut your fun early, and the factory heads don't flow over 300cfm until 700 lift, where a modern set of cnc ported heads might make lots of power with the factory camshaft. That's why I specified ls2. I don't know what the cam is like in this Cad stock but probably less than 190@050 and around 400 lift. It doesnt matter what head you put on it at that point, not a lot will happen.
My point is with an ls2 the shape of the curve will be similar. My point also stands that putting a cam with 600 lift and 240@050 might work really good at even 2500rpm on the dyno with no manifold vacuum, that camshaft is going to cause issues at 1500rpm and 15" of vacuum.
I can't find the port volumes of these heads but they look like they are in the 240-260cc range. Really small for the 514 cubes they are tasked with feeding.
Do you think you could overcam a 500 inch ls stroker with stock ls1 heads, or do you think that every camshaft up to the big cam here you put in will add power everywhere when you test it on the dyno?
I still have a small tackle box full of Q-jet needles and crap . lol
Is something wrong with the current lot of hydraulic lifters, seems a lot more issues with them than in the past. Has the quality been reduced. The only issues you use to see was ‘pump up’ and loss of valve control over 5000rpm?
Made in China...
Michael Angelo I guessed that, but who is going to start paying for rebuilding engines destroyed by hydraulic lifters that have lost their guts.
We need to name and shame companies that sell sub standard parts, more so us backyard engine builders with low budgets don’t loose out.
@@vintagetintrader1062 Yes, I agree.
Those numbers are incredible!!! The torque curve is a perfect for some street fun
Agreed!
This era of cadillac really were engineered so well these engines are dead reliable and super balanced with unmatched smoothness .
Cant wait to see boost!
I'm thinking the perfect truck/4×4 engine.
Hi
I faver the use of Q JETS
Y ?
Driveability serviceability
Center fuel bowel
Tuneability
Duel booster primary
Best of both driveability
Raceing
Won several street
Races with a 327 L 79 1965 NOVA Wagon have more details
And info
I like all the details
We're did u get the 4 4 2
Q-jets get a bad rap because people don;t know how to tune them and they don;t have the millions of parts available holleys have. Holleys are for if you want to tinker and get every .01 second out of it. Q-jets and Edelbrock performer carbs are for when you want driveability. I'd take a well tuned Q-jet of either if going carb, although these days its gonna have some kind of aftermarket EFI on it instead. I'd like to see what the engine makes just swapping on a holley EFI or similar system.
Yall need to include an aftermarket EFI swap in these videos with the carbs. They're cheap enough now, it ought to be Q-jet vs efi since yall havent gotten to badass racecar stuff yet and most people are gonna want efi for set it and forget it tuning. no more tweaking carbs as the seasons change fron summer to winter. just get in it and crank it up and go.
this is a damn good comparison video with a motor that i always found fascinating....big brute torque at an ultra low rpm and massive power from the caddy!
Is it possible to see the brake specific fuel consumption?
I used to be pretty good with Q-Jet's.
The first thing I did was to have my buddy TIG weld the leaky plugs in the bottom of the float bowl, then start massaging the jets and metering rods and adjusting the secondary air valves. Way more reliable than the Holly's with the old power valves that almost always needed replacing after a backfire.
Porting heads is usually a waste of time and money.
awesom vid, well done Richard and team, keep'em coming
Hard to see but I think the secondary air valve wasn't opening enough. I'm guessing they will loosen up the tension on it to provide more air and fuel lifting the metering rods out of the orifices and maybe a metering rod change or a metering rod hanger change also. Maybe some other mods requiring the top to come off. Might have to change the secondary throttle blade angle also
Where are my quadrajet fans... Crickets
In the 60’s they had leaded premium fuel at the pump . The 72cc heads were on 472” motors . 472s were more common.
not just on the 472s
The 500 from 70-73 had the 76cc head as well.
Those heads even ported must be turds. Also, I wonder if the collapsed lifter happened on just that run and what caused it? Not like you're spinning it very high.
too much preload-there is a story
You need to get together with Uncle Tony's Garage. The two best tech channels on the internet
Lol... He's so far ahead of Tony...
@@michaelangelo8001 I don't think that's quite true. They do two different things. I think.of Richard as the lab tech, and Tony as the field guy.
Don't forget, Tony has a history in this world that goes back almost 40 years. He.must be doing something right.
@@ericlandstrom6155 I'm not putting anyone down, but I have more "history" than either of them.
When I saw Richard's first video attempts, I was disgusted, frankly. He looked an acted like an arrogant, know-nothing, baldheaded jerkoff.
But now that he's dropped the fake act, and started putting real meat and potatoes on the table, I can see that the guy actually has an incredible amount of experience in comparison to your average internet wannabees.
Tony knows the ordinary things that all of us with any experience with cars already know, but Richard takes us into a world that 99% of us could never afford to experience.
Dyno time is VERY expensive, and most people in this audience can not afford it. Everytime you watch one of these videos, it's like he is just handing you money.
Tony bores me, I know lots of people like him, personally. But the information that Richard provides is on a completely different level.
you got all that from a video?
@@richardholdener1727 Many videos.
Dyno flogging a Caddy, anyone who's been in a cell during a test knows how noisy it is, yet the Caddy still sounds quiet and refined.
True. But it is on mufflers. I'm not saying Caddys aren't quiet, but most of his tests are run open headers.
Because the motor is so huge it sounds refined I know guys running an Ls2 (364ci) with cams in the 254 duration area and they sound like a damn top fuel car lol so no surprise a 500ci motor it's like nothing to it 🤔
@@coreyrowe2052 /lp
Would definitely deceive someone , just a mild small block
Put it in a 78 2 door Caprice , with a T5 tremec
Love waking up to Coffee and Richard lol.
Sippin on some high octane liquid right now!☕☕
I'm hittin the milk....straight up
“Coffee and Richard” sounds a bit more suspect
@@HioSSilver1999 🤣
Special Agent Jim Harris, SSD. Lol
500 lft lbs at 2000 rpms... LOL
That's almost hellcat levels
its a Pontiac, Olds, Buick and Caddy thing. My daily drivers have that kind of torque with Pontiac 455s. They are still making 500ftlbs at 5500rpm too. The Hellcat needs a blower to do it.
It's the cubic inches (and the stroke, cam, etc.) that allow for the torque. It is an impressive amount of torque is all I was saying.
@@futon02 It is awesome torque, its why I love these engines. The Caddy is just too hard to find and the cost of parts is a bit more, Pontiac stuff is easy to come by cheap, even if the aftermarket thinks they need a premium for parts.
You can take a bbc that is the same size ci and you won't make that much torque, possibly nowhere in the RPM range. You have to drastically increase the cubes on a bbc to get that kind of grunt.
the difference is in the intake runners and ports. The bbc has lazy ports at low RPM, they are great for over 5500rpm, but the velocity isn't there down low from idle to 4500.
The longer runners with higher velocity of the Pontiac, Olds, and Caddy fill the chambers very well from 2000 to 4500 in stock form, its difficult to kill the bottom end on these things. The Pontiac has a venturi shape that speeds up the airflow before it goes into the cylinder, whereas the chevy and Buick do not.
The Caddy has very long runners, is a wide engine so you get a larger column of air moving through a relatively small hole, that makes for a higher velocity, but it limits RPM potential. he way it drops off at 4500 is indicative of that. Make the ports bigger but keep the length and you allow the engine more RPM potential without sacrificing much bottom end.
The longer stroke helps, but if you take the same engine design and build the same ci with different stroke and bore, you will get the same power from it, the size of the bore doesn't matter much as long as its large enough to clear the valves and not shroud them, same with the stroke, if it has a smaller bore but is still the same ci as the large bore short stroke, its going to make power roughly the same. There is always some variance.
The power is in the heads and intake runners. The cam timing dictates where in the RPM range any particular engine will make its power.
The fun thing about grunt monsters like my 455s and this Caddy, is we can run a 2.73 gear instead of a 3.73-5.13 and often go faster than other engine designs that need RPM and gears to run well.
So my daily driver iron head flat tappet cam 455 with a 3.08 can run low 11s easily where a 350 chevy needs 4.88s, aluminum heads and lots of RPM to come close, Sure there is 100ci difference, but the big difference is in how much torque its making and how long that torque is used to accelerate the vehicle. 500ftlbs over 3500rpm is very different than 350ftlbs over a narrow band higher in the RPM range where its making more HP.
The chevy guys I used to race in the 90s said my cars don't sound like race cars, they sound like I am going to the store for a loaf of bread. My engines never got over 6000rpm back then, no need to.
Its all fun with math and physics. Pontiac guys often race cars with full interiors and street manners, running elevens, tens and nines NA, because they can. Caddys can too, and in a light vehicle they work great if you go tall enough with the gears and can get it to hook.
That is another thing that takes different thought with the grunt engines. A deeper gear allows the rear tires to catch up to the quicker, so it doesn't spin as long but this much grunt means its very easy to do an 1/8 mile burnout with a 2.73 posi leaving from idle with a 275 tire under a heavy car. Been there done that, just whack the throttle and the tires go up in smoke until you let off. These things are stupid fun.
@@SweatyFatGuy I get it. My first car was a Pontiac large journal engine. I cut my teeth on the quadrajet and Pontiac combination
QUICK FUEL QUICK FUEL QUICK FUEL!!!!!!!!!!!!!!!!!!!
Why are they doing head work for a carb test
Q jets never beat Holly or edlebrock carbs
500 foot pounds of Torque @ 2000 with a 248 degree cam.
I don't think I've ever seen that much down that low with a cam that big. Really amazing.
Great video. How much $$ for a crate motor?
I'm gonna say the Q-jet carb
I love what he is doing here. I build a few engines and I have a friend that owns a Superflow 901 dyno with the later windyn software. I have also done some things like this where we would try different things on the engine trying to get an improvement in the power numbers. Even things like changing the air bleeds on the Holley carbs will make a big difference on certain combinations. It's always fun and educational to be able to do this and I especially enjoy what Richard is doing here and respect that it's a lot of work to do all the parts swapping, taking the thing apart time after time, many times to be disappointed at the results. I must tell everyone that this is the real way to use a dyno, it's a tool for learning and that Richard's work can help everyone see how things need to be done so a to get proper results. Great job on this and every other engine project he has done.
Didn't some monster trucks use those motors ?
They were called q junk for a reason
Not a GM guy but these always intrigued me. Just wish there were more around.
If the holley and q-jet are the same cfm, I'll actually take the q-jet for street driving because of the primaries are smaller and more responsive, probably would at the track also, as there is no real point in replacing a perfectly good carb with a perfectly good carb, I mean I've committed sacrilege and ran a q-jet on a 302 ford for a while.. it only takes an adapter. The secondaries needed some tuning otherwise it ran fine. If the manifold is a 4 hole holley style max power is probably the holley, if the manifold is a spread bore then I'll take the q-jet.
I had a 302 Ford with a performer 289 intake. I had an edelbrock 600 that was damaged and would cause a rich misfire when the secondaries opened. An adapter and Qjet later and it had never pulled so hard. Qjets aren't any more diffict to tune and AFB or performer style carbs.
@@timothybayliss6680 I used the q-jet till i got a holly 600, I was using an original torker with a twist and needed a carb, hell the motor was stock.