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#1
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Q-Jet on Olds 455 surprizes Nicks Garage
Dynoing the Olds 455 the first impression Holley carb was the way to go until they bolted on the original Q-jet. https://youtu.be/5Iu0eJUjEAQ
Last edited by Big Bear; 06-10-2024 at 10:29 PM. |
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#2
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This is the correct link. https://youtu.be/5Iu0eJUjEAQ?si=wa4fRXwDZZBnO1cU
the old square bore on a spread bore intake senario too. that can't be ideal for the Holley.
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1979 Firebird Trans Am 301/4spd (Now 428) 1977 Firebird Formula 400/Auto 2007 Grand Prix GXP 5.3L Last edited by 74Grandville; 06-10-2024 at 10:19 PM. |
#3
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loved the guys reaction!! the idle circuit wasn't correct. so I'm thinking it could have been dialed in a bit more for more power. love q-jets !!
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#4
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Good thing I didn't give them a 1976 or later Olds Q-jet for the testing or they would have been dialing 911 for old Tony!
The unit they used was a 1970-74 style Olds Q-jet. They aren't that great anyplace and I avoid them for high performance work. Probably OK on the dyno at that power level but Olds (and Cadillac) continued to use the poorly located hinge pin and large float from the 1965-68 designs. I'd add here that it still has an advantage in that scenario as a spread bore carb doesn't require an adapter and lines up perfectly with the center of the plenum areas vs the square flange carb they were testing. I've been asked more times than I can count to do that type of testing, dyno and at the track. I very quickly learned to keep a box of diapers close by so I could hand them out when the old/ugly Q-jet whipped up on the Holley and Holley cloned stuff!.......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#5
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In my 63 GP I installed a 65 421 years ago with carter afb. Tried edelbrock aluminum intake with square bore small Holley. Then tried holley spread bore with iron qjet intake rejetted both rejetted. Then I acquired 70 455 ho qjet. I tried it. Cant remember if I changed jetting. It was better everywhere,performance mileage, response on the street.
Last edited by sdbob; 06-11-2024 at 08:43 AM. Reason: Spelling |
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#6
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When one looks at all the cars in NHRA classes that have been forced to use them and the times that those cars turn it becomes very clear that those who use a blanket statement that they suck just don’t know about them because they have spent their entire carburetor learning curve with Holley’s.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#7
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My 70 qjet (reworked by cliff) made around 3-4 hp more on the dyno than shops 850 Holley DP.
On nicks olds 455 dyno engine I was more concerned with the oil pressure dropping through the run but it made good power for what it was.
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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86' |
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#8
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You could tell no one in that room could even tell what size it was. I was kind of shocked at the oil psi dropping as mentioned plus 19 psi at an idle on a new engine? Yikes.
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“Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan Press On! has solved and always will solve the problems of the human race.” ― Calvin Coolidge |
#9
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To me working on all kinds of engines on the dyno, a Holley carb is like a anvil and a mini-sledge. It will get the job done and can deal with huge changes very quickly and easily to get an engine in the ball park. A Quadrajet is like a fine surgical instrument. If your willing to put in the time and effort, they are just fantastic and do everything well. No matter what I do tuning wise, I can't match the economy of a Q-Jet with any Holley I have ever used. Pontiacs just seem to really love Q-jets.
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#10
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Right now, I'm running a 69 cast iron manifold w/ a matching Q-jet from a 428. Rebuilt with one of Cliff's kits & parts. By far, the best street combo to date.
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65 Tempest, 400, TH400 86 Fiero SE 2.8 |
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#11
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I wish they would have stuck a sock in Dr. Olsmobile's big yapper, and made him sit in the corner. He had nothing worth contributing to the dyno session. The big guy, named Tom, had they right ideas of what to try next.
I'm glad Cliff got to see that. I was wondering about that specific Q-Jet... The engine owner Tony mentioned that 800 cfm Olds carbs were rare??? Are not nearly all Q-Jets after 1976, 800 cfm units? Cliff? I don't think they mentioned who built the carb. Nick does all this engine building, but doesn't seem to want to tear into any carb that's not a Holley. He worked at a GM dealer, way back. Nick says all his dyno carbs are new carbs. It was nice to see a 53 year old carb stand in there!!!
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
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#12
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I wish they would have stuck a sock in Dr. Olsmobile's big yapper, and made him sit in the corner. He had nothing worth contributing to the dyno session. The big guy, named Tom, had they right ideas of what to try next.
I'm glad Cliff got to see that. I was wondering about that specific Q-Jet... The engine owner Tony mentioned that 800 cfm Olds carbs were rare??? Are not nearly all Q-Jets after 1976, 800 cfm units? Cliff? I don't think they mentioned who built the carb. Nick does all this engine building, but doesn't seem to want to tear into any carb that's not a Holley. He worked at a GM dealer, way back. Nick says all his dyno carbs are new carbs. It was nice to see a 53 year old carb stand in there!!!
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#13
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The only big cfm early carburetors are the 1971 HO 455 units (and the 1971 400 4speed), 1971-74 Buick 455's and 1973-74 Super Duty.
All the non CCC front inlet carbs from 1975-up will be the larger castings and most of the side inlet as well provided they are the later hot-air or electric choke models. The 1971 455 HO carbs flow 827cfm, the 71-74 Buick 455's and Pontiac Super Duty Q-jets are 850cfm. All of the large casting models are typically dubbed "800" cfm but the flow numbers on them are all over the map as the factory limited the full open angle of the secondaries for the application. A good example of this are the Pontiac 301 Q-jets. The stop on them is so long that the air flaps barely open. About 5 seconds with a grinder to shorten up the stop and they are 850cfm. My bood describes the optimum opening angle for the secondary air flaps for maximum CFM without going too far with them. I used a 1977 Pontiac carb on five different engines that powered my Ventura over a span of nearly 40 years. It's been on the dyno countless times and thousands of track runs with PLENTY of back to back testing against other types of carburetors. Not one single time, dyno or at the track has anything outran it. I'll also add that a grinder or sanding roll has never touched it, so it's a completely "stock" unit with a little ground off the stop to get it to "850" cfm, and recalibrated exactly for what it was being used on. The only times to date it was "outran" was at the track during one of the HPP "Shootouts". I replaced both the intake and carburetor with a Tomohawk, 1" spacer the 4781-2 Holley DP carb. For all testing that day that combo was worth a solid 2mph on top end over all other carbs, intakes and spacers tested. Even so the 1977 Pontiac Q-jet on a factory cast iron intake with no spacer ran the quickest ET that day, besting out the big intake and Holley by .02-.03 seconds. Another example clearly showing how big intakes and carbs do make more upper mid-range and top end power, but more average power gets the car there quicker as it leaves harder (improved 60' times) and more power in the loaded RPM range.......FWIW.....
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#14
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The only big cfm early carburetors are the 1971 HO 455 units (and the 1971 400 4speed), 1971-74 Buick 455's and 1973-74 Super Duty.
All the non CCC front inlet carbs from 1975-up will be the larger castings and most of the side inlet as well provided they are the later hot-air or electric choke models. The 1971 455 HO carbs flow 827cfm, the 71-74 Buick 455's and Pontiac Super Duty Q-jets are 850cfm. All of the large casting models are typically dubbed "800" cfm but the flow numbers on them are all over the map as the factory limited the full open angle of the secondaries for the application. A good example of this are the Pontiac 301 Q-jets. The stop on them is so long that the air flaps barely open. About 5 seconds with a grinder to shorten up the stop and they are 850cfm. My book describes the optimum opening angle for the secondary air flaps for maximum CFM without going too far with them. I used a 1977 Pontiac carb on five different engines that powered my Ventura over a span of nearly 40 years. It's been on the dyno countless times and thousands of track runs with PLENTY of back to back testing against other types of carburetors. Not one single time, dyno or at the track has anything outran it. I'll also add that a grinder or sanding roll has never touched it, so it's a completely "stock" unit with a little ground off the stop to get it to "850" cfm, and recalibrated exactly for what it was being used on. The only times to date it was "outran" was at the track during one of the HPP "Shootouts". I replaced both the intake and carburetor with a Tomohawk, 1" spacer the 4781-2 Holley DP carb. For all testing that day that combo was worth a solid 2mph on top end over all other carbs, intakes and spacers tested. Even so the 1977 Pontiac Q-jet on a factory cast iron intake with no spacer ran the quickest ET that day, besting out the big intake and Holley by .02-.03 seconds. Another example clearly showing how big intakes and carbs do make more upper mid-range and top end power, but more average power gets the car there quicker as it leaves harder (improved 60' times) and more power in the loaded RPM range.......FWIW.....
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
#15
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While we are on the subject of Q-jets and CFM ratings, performance potential, etc, consider this. Below is a link to Brent Flynn's Firebird at the track. It's a pretty "basic" engine build, 408cid, upgraded rods, pistons, and ported early "D" port cast iron heads. It's higher compression and uses a Comp flat solid 300B camshaft. On top of the intake sits a 1969 Q-jet, the smaller casting, set up for E-85. This Q-jet has the better hinge pin location and smaller float but the same size casting as the Olds Q-jet Nick was impressed with. It would have made more power on the dyno simply due to the superior design and improved fuel control. I've dyno and track testing both variety back to back enough times to know that I would never use one of the early units with the short hinge pin and large float unless class rules mandated it.
https://www.facebook.com/brentwillia...21130332784502 Brents car is also a prime example of the performance potential of the Pontiac 400's. No roller cam, no stroker crank, no CNC ported aluminum heads, no big intake manifold or big CFM aftermarket carburetor. Just a well thought out combination to end up with a strong running Pontiac without a lot of aftermarket or exotic parts......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#16
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As Cliff mentioned, the adapter could have held back the Holley slightly; air fuel mixture like a straight line direction.
The guys just didn't want to give up on the Holley, even confronted with the numbers. But honestly, an 850 Holley probably does not flow any more or possibly even as much as a 750 Q-Jet WHEN the Holley is sitting on top of an adapter. Now the real question is: what would have the numbers been with a 850 TQ or a 1000 TQ, both of which would require no adapter? Or is the 750 CFM of the Q-Jet actually enough for the 455 Olds? Jon
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"Good carburetion is fuelish hot air". "The most expensive carburetor is the wrong one given to you by your neighbor". If you truly believe that "one size fits all" try walking a mile in your spouse's shoes! Owner of The Carburetor Shop, LLC (of Missouri). Current caretaker of the remains of Stromberg Caburetor, and custodian of the existing Carter and Kingston carburetor drawings. |
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#17
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I have run Qjets I've taken the time to dial in and Holley/Demons. Like Mike said way easier to start dialing in a Holley/Demon.
As far as the adapter debate-yes theoretically the flow probably is not as great with a square bore but I did an at the track swap years ago on my first E head motor. I kept the HO intake so I could use my Shaker until I could find another Shaker base to modify for Holley/Demon clearance. I had run on my RAIV heads on a 455 then a 400 and the 73 SD SR replacement I had Brad Urban tweaked, since then tweaked by Cliff but not run since that. 259/262 @ 0.050 solid roller and ported E heads so maybe a little more air flow than ideal for the HO. At the track swapped on an out of the box Demon 850 DP WITH the adapter picked up 0.3 seconds at the track! So if it was hurting air flow the motor sure did not know it. Later swapping a Torker II -not same day-it picked up a bunch more and idled even better with the single plane and the Demon. I had blended the adapter some to smooth out any transitions and it was the open one not the 4 hole like the Edelbrock. https://www.edelbrock.com/quadrajet-...-kit-2697.html https://www.amazon.com/Trans-Dapt-20.../dp/B000CQ47QK I have noticed this new edelbrock open does slightly move the carb centers between square bore and spread bore. the GM Racing SBC iron intake for both for classes that require a cast iron intake does the same. https://www.edelbrock.com/competitio...fold-2693.html
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4-sold 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs 1964 Corvette Coupe 327 4 speed |
#18
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Quote:
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
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