cfm quadrajet?

[ronm69c10]

i need to buy a new quadrajet to replace one that is cracked and old.I found an 800cfm quad at a good price.My question I have a stock 454 out of a p3o with headers.I have no ideal what was done during rebuild 5000 miles ago but motor seem's to be stock.numbers on bad carb. are 17080212. Is a 800cfm. a good choice. Also turbo350 trans,373 rear in truck. RON

[harpo231]

650 for stock

[Steeveedee]

Big inch Pontiacs have been fitted with 800 CFM Q-Jets. Your 454 counts as big inch. If it were up to me, I'd be calling Cliff Ruggles for information. The removal of some of the venturi material to accomplish that kind of air flow makes these carbs a little touchy to make idle right.

https://cliffshighperformance.com/

[mike16]

and buicks from the early 70's

[Coley]

New internal kit will get you there
....new jets, rods, spring, float etc.
This upgrade will give you greater flow for the bigger cubes.

Coley

[Problems]

Originally Posted by Steeveedee

Big inch Pontiacs have been fitted with 800 CFM Q-Jets. Your 454 counts as big inch. If it were up to me, I'd be calling Cliff Ruggles for information. The removal of some of the venturi material to accomplish that kind of air flow makes these carbs a little touchy to make idle right.

https://cliffshighperformance.com/

Cliff is “the” guy for quadrajets, he literally wrote the book on high performance modifications. but he can get pretty far behind if you want him to build a custom one. Last year about this time he told me he had a 6 month wait, everyone sends him stuff as spring gets near. I didn’t have that kind of time so I tried quadrajetpower out of Texas, after a couple of long conversations with them. they built a 800 cfm that’s on a 467 Pontiac in my wife’s 69’ firebird. I wouldn’t hesitate to go with them again, they did a nice job.

[truckster]

Originally Posted by harpo231

650 for stock

All Quadrajets were rated a minimum of 750 CFM; there are no 650 CFM Quadrajets.

The Quadrajet will work on almost any size motor because of the way it is designed. GM used them on engines from 283 cubic inches to high-performance 455s and Cadillac 500 cubic inch engines. As long as it's in good shape, that carb should work fine on your 454.

[Steeveedee]

Originally Posted by Problems

Cliff is “the” guy for quadrajets, he literally wrote the book on high performance modifications. but he can get pretty far behind if you want him to build a custom one. Last year about this time he told me he had a 6 month wait, everyone sends him stuff as spring gets near. I didn’t have that kind of time so I tried quadrajetpower out of Texas, after a couple of long conversations with them. they built a 800 cfm that’s on a 467 Pontiac in my wife’s 69’ firebird. I wouldn’t hesitate to go with them again, they did a nice job.

Multiple responses here-

Yes, Mark is another good source for Q-Jets.

I'm going to have to say that I've never seen a 283 with a Q-Jet, though. I HAVE seen them with 4GC Rochesters.

Whether you go with Mark or Cliff, make sure to give them the number off the side of the carburetor as well as the intended application, which includes cam, trans, etc., if you buy a kit. You might try Ken at Everyday Performance as well; depending on where you live, he might be closer. I rebuild my own, though. There are many parts in a carburetor that aren't in a regular kit, like the cam that pulls the secondary metering rods out of the jets when the secondary air valve opens. Cliff's kits supplies them, but I haven't bought kits from Mark or Ken, so I can't say one way or the other, with them.

[mike16]

Cliff did not write "the book". Doug Roe wrote "the book" back in '81. and it has gone through several editions. Doug Roe's book, "used", sells for more than Ruggles does new. Roe's book covers an enourmous amount on the Q-Jets including alot more on mods than Ruggle's does and he research it himself. If your going to build a Q-Jet Roe's book is still hands down the best origonal source. I bought a new copy of Ruggles book for less than 8 dollars while Roe's book, 35 years later sells for about 20 dollars. It is truly the diffinitive source.

[67_C-30]

Originally Posted by truckster

All Quadrajets were rated a minimum of 750 CFM; there are no 650 CFM Quadrajets.

The Quadrajet will work on almost any size motor because of the way it is designed. GM used them on engines from 283 cubic inches to high-performance 455s and Cadillac 500 cubic inch engines. As long as it's in good shape, that carb should work fine on your 454.

X2

The stock carb on a '83 Z28 with a boat anchor 305 is 800 cfm. In the late 70's most quadrajets being made were 800cfm carbs, but the metering for smog and emissions control made them less desirable carbs.

Like truckster said, don't get too hung up max cfm. A stock peanut port 454 isn't going to need the full 750 or 800. The earlier non emissions 750's are fine for most engines 95% of the time. The straight inlet early 70's Buick 755 carbs are great if you happen to find on, but they need the throttle bracket changed up if you running an auto trans.

For s stock or mild 454 you'd be better off looking for a early 70's 402 or a early to mid 70's 454 carb if you just want to put a kit in it and run it. They will be metered pretty close to what you want as they are.

[Steeveedee]

Originally Posted by mike16

Cliff did not write "the book". Doug Roe wrote "the book" back in '81. and it has gone through several editions. Doug Roe's book, "used", sells for more than Wiggles does new. Roe's book covers an enourmous amount on the Q-Jets including alot more on mods than wiggle's does and he research it himself. If your going to build a Q-Jet Roe's book is still hands down the best origonal source. I bought a new copy of wiggles book for less than 8 dollars while Roe's book, 35 years later sells for about 20 dollars. It is truly the diffinitive source.

The price of a book means little for the value received. I've bought many new books for less than used books, on Amazon. Can you point me to a failure on the part of either author on making a recommendation of carburetor work? Have you made a "better mileage or best of drags ever with a Q-Jet" comparison? Please let me know.

[suville]

I've used SMI Sean Murphy Induction and was very happy with the carb. He worked for the "Carb Shop" before opening his own

[Alex V.]

The Quadrajet was only made in 2 CFM's: 750 and 800. The vacuum secondaries make it, in a way, a variable CFM carb. because when adjusted properly the secondaries only open as far as engine vacuum will pull them open. Many factory small blocks came with Q-jets - 650 is a good minimum for a stock big block but when speaking of a Q-jet it won't be "too much".

[mike16]

Originally Posted by Steeveedee

The price of a book means little for the value received. I've bought many new books for less than used books, on Amazon. Can you point me to a failure on the part of either author on making a recommendation of carburetor work? Have you made a "better mileage or best of drags ever with a Q-Jet" comparison? Please let me know.

.
I have not made a better mileage or best of drags ever with a q jet comparison. why reinvent the wheel. It does not increase credability do do what others have already done, unless your audience does not know that. Thats why Roes book remains the best source on the Q Jet.

But I do make choices based on moral and ethical grounds. Does that Count? I have a Dyno App so I could have lied and say yes I did. It does not take more than a few questions to find out if someone is fibbing.

Hands down Roe's book is the better value. think about it.... a 35 year old used book on the subject going for more than a new one. The old one covers alot more.

And ultimatley.... I'm giving credit where credit is due. It avoids the issue of plagerism if you can reference your sources. But standards vary. No Chewing Gum or pencils. But now that the word is out on Roe's book. I'll buy a few and watch their prices rise.

all kidding aside it was stated that Cliff's book was "the book". It is not. Roe's was, is, and always will be. I like to set the two side by side and let others make an informed choice.

[truckster]

Originally Posted by mike16

.
I have not made a better mileage or best of drags ever with a q jet comparison. why reinvent the wheel. It does not increase credability do do what others have already done, unless your audience does not know that. Thats why Roes book remains the best source on the Q Jet.

But I do make choices based on moral and ethical grounds. Does that Count? I have a Dyno App so I could have lied and say yes I did. It does not take more than a few questions to find out if someone is fibbing.

Hands down Roe's book is the better value. think about it.... a 35 year old used book on the subject going for more than a new one. The old one covers alot more.

And ultimatley.... I'm giving credit where credit is due. It avoids the issue of plagerism if you can reference your sources. But standards vary. No Chewing Gum or pencils. But now that the word is out on Roe's book. I'll buy a few and watch their prices rise.

all kidding aside it was stated that Cliffy's book was "the book". It is not. Roe's was, is, and always will be. I like to set the two side by side and let others make an informed choice.

I'm just wondering why you feel the need to belittle the guy by calling "Wiggles" and "Cliffy". Cliff Ruggles is very knowledgeable and also a really nice guy. He's answered phone calls for many of us on this board and given his advice free of charge. I don't think belittling someone like that is what this board is about.

[brown7373]

I have both books and use them both. As truckster mentioned, you can call and talk with Cliff. You can discuss anything and everything about your carb issues or questions. And, he can supply complete quality parts and rebuild kits, which run circles around generic parts store kits. Do they cost more? Yep, but I have found they are WELL WORTH IT!

[67_C-30]

Originally Posted by brown7373

I have both books and use them both. As truckster mentioned, you can call and talk with Cliff. You can discuss anything and everything about your carb issues or questions. And, he can supply complete quality parts and rebuild kits, which run circles around generic parts store kits. Do they cost more? Yep, but I have found they are WELL WORTH IT!

I have both books as well. There are some things in both books that are not in the other, so they both have value, IMO.

I can't say which guy is the best, but I can say if you go to any BOP event that has drag racing it's amazing to see how fast some of the cars are with Cliff's Q-jets.

[leddzepp]

Who are Ruggles and Roe?

Bob Stone is the man when is comes to Q-Jets

[Steeveedee]

Originally Posted by leddzepp

Who are Ruggles and Roe?

Bob Stone is the man when is comes to Q-Jets

Toe-may-to, toe-mah-to and tomate in a Mexican standoff!

[HO455]

Originally Posted by truckster

All Quadrajets were rated a minimum of 750 CFM; there are no 650 CFM Quadrajets.

The Quadrajet will work on almost any size motor because of the way it is designed. GM used them on engines from 283 cubic inches to high-performance 455s and Cadillac 500 cubic inch engines. As long as it's in good shape, that carb should work fine on your 454.

Well technically that isn't true. Due to internal GM rules and issues there were Quadrajets that left the factory as 650 cfm units. Most notably the 400 ci first gen Firebirds. The exact engine in a GTO made 350 HP but in the Firebird it made 335 HP. The carburetor was the same on both engines with the exception that the secondary throttle shaft was limited to prevent full throttle. So yes both throttle bodies were capable of 750 cfm but unless you modified the secondarys you wouldn't be getting 750 CFM. There are more strange exceptions but none of the are very common. Like a Q-jets on 230 ci engines. To run them on these small cubic inch engines there are physical internal differences from the large cubic inch engine carbs that relate to idle quality and low rpm throttle response. It is easier to find a carb that started life on a similar sized engine unless you are aware of the challenges you are facing. In your case the 800 cfm units came on 454's from the factory. In fact I believe it is the most common application of the 800.

[67 chevelle]

Originally Posted by truckster

All Quadrajets were rated a minimum of 750 CFM; there are no 650 CFM Quadrajets.

The Quadrajet will work on almost any size motor because of the way it is designed. GM used them on engines from 283 cubic inches to high-performance 455s and Cadillac 500 cubic inch engines. As long as it's in good shape, that carb should work fine on your 454.

True

[old Rusty C10]

lets not get into name calling here this thread is a good source of info and in some instances user opinion of which we all have one, and one is not to be bashed for theirs

[Steeveedee]

Originally Posted by HO455

Well technically that isn't true. Due to internal GM rules and issues there were Quadrajets that left the factory as 650 cfm units. Most notably the 400 ci first gen Firebirds. The exact engine in a GTO made 350 HP but in the Firebird it made 335 HP. The carburetor was the same on both engines with the exception that the secondary throttle shaft was limited to prevent full throttle. So yes both throttle bodies were capable of 750 cfm but unless you modified the secondarys you wouldn't be getting 750 CFM. There are more strange exceptions but none of the are very common. Like a Q-jets on 230 ci engines. To run them on these small cubic inch engines there are physical internal differences from the large cubic inch engine carbs that relate to idle quality and low rpm throttle response. It is easier to find a carb that started life on a similar sized engine unless you are aware of the challenges you are facing. In your case the 800 cfm units came on 454's from the factory. In fact I believe it is the most common application of the 800.

Many 455 Firebirds had the 800 CFM carb as well.

[67_C-30]

Again, the majority of Q-jets, on most everything made after 1976 was M4M casting 800 cfm carbs. Most carbs on everything after 1976 had the same 1 7/32" primaries as the Super Duty 455 carbs from '73-74. 800 cfm Q-jets are not rare or uncommon by any stretch. The HP versions are, not an 800 cfm capable CFM carb.

[geezer#99]

Originally Posted by 67_C-30

Again, the majority of Q-jets, on most everything made after 1976 was M4M casting 800 cfm carbs. Most carbs on everything after 1976 had the same 1 7/32" primaries as the Super Duty 455 carbs from '73-74. 800 cfm Q-jets are not rare or uncommon by any stretch. The HP versions are, not an 800 cfm capable CFM carb.

Just to clarify, you mean 1 7/32 primary Venturi and not primary throttle size.
Is that correct.

FWIW I thought the last 800 came from the 80 T/A with the 301 turbo. 750 cfm after that.