# 64 GTO-Carter AFB Replacement Suggestion Needed



## tguggino (Aug 31, 2013)

Hi all.

We restored our 64' 389 GTO motor with the original Carter AFB (rebuilt) to keep everything authentic. Turns out, the AFB is causing some issues. (hesitation, poor idle, etc). The shop is suggesting we replace the AFB (if we can't get it working correcting) with an Edelbrock 750. 

The 389 was just rebuilt, valves done, 9:1 compression, ported (stock 1964) heads. They put a more aggressive cam in, but I don't have the spec. It idles smooth, revs strong to about 5500 rpm, good top end as well. 

We are looking for some advice and/or suggestions about the best carb to use. 

https://www.youtube.com/watch?v=zRtQ1ArzUGA

Thanks 
Tom


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## geeteeohguy (Feb 2, 2008)

The best carb to use is the AFB you have, rebuilt by a qualified professional. It is calibrated for your car. Edelbrock carbs are generic 'one size fits all' units, and are not as good as the AFB. They are seen as an 'easy out' by those who don't understand carbs, and simply want to band-aid the situation. Adding one will get you going for now, but will be a downgrade.


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## tguggino (Aug 31, 2013)

If we had to swap out, what would be the best aftermarket?


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## Koppster (Jul 27, 2008)

I vote for a Quadrajet rebuilt for a Pontiac by someone who knows what they are doing.

That said, the link below is for the carburetor shop, the guy, Jon, is an ace on Carters.

THE CARBURETOR SHOP

Rick


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## tguggino (Aug 31, 2013)

Good info. Thanks. If we wanted to go aftermarket. Would you recommend holly or Edelbrock?


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## tguggino (Aug 31, 2013)

If we look to go Qjet, is there a modern one that would fit on a 64 Gto stock manifold?


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## 1968gto421 (Mar 28, 2014)

Probably the easiest way to do that is with an adapter, here's a link to one:
Edelbrock Carburetor Adapters 2692 - Free Shipping on Orders Over $99 at Summit Racing

That said, a better way is to use a '68-'72 Pontiac 4bbl intake, usually cheap to come by. They flow well and the Q-jet bolts up with no adapters. An adapter will limit mid and upper range performance.


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## tguggino (Aug 31, 2013)

Would the later year intake bolt to 64 gro heads?


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## rickm (Feb 8, 2012)

no, it wont.


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## 1968gto421 (Mar 28, 2014)

{That said, the link below is for the carburetor shop, the guy, Jon, is an ace on Carters.

THE CARBURETOR SHOP

Rick[/QUOTE]

Looks like if authenticity is important, the Carb Shop is the way to go, per Rick.
Cliff Ruggles, the Q-jet guru, states he uses the Carb Shop to provide him with parts. This is a strong recommendation for them. :thumbsup:


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## BearGFR (Aug 25, 2008)

:agree: In this day and age, the number of shops - even professionals - who really know their way around a carburetor are dwindling rapidly. Couple that with a pro shop who makes all their money based on 'time actually spent' vs. 'standard shop rate time' and it's not hard to understand why they'd jump to recommending a replacement instead of repairing and tuning the AFB you already have. The more time they actually spend on your car, the less profit for them.

AFB's are good carbs and unless there's something seriously wrong with it (cracked body, etc.) I'd bet real money up against the hole of a rolling donut that it can be made to run like it's supposed to without an extreme amount of time, effort, and expense.

Cliff Ruggles has an excellent book out on the QJet. I'll bet if you spend a little time looking, you'll find similar reference material on the AFB. Get some reference material, study it, and don't be afraid to work on it yourself. Carbs have this 'mystique and folklore' around them of being difficult to understand, hard to work on, etc. It ain't true. You DO have to know what you're doing, but the good news is that acquiring that knowledge is possible for the average bear as long as he's willing to try.

Bear


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## tguggino (Aug 31, 2013)

Good advice. Thanks. 


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## PontiacJim (Dec 29, 2012)

Trying to nail down a "best" replacement is always a matter of opinion - as you have seen. If you don't know carburetors or have not played "swap & change" yourself, then you are at the mercy of others who have and who also have their own preferences and dislikes.

Here is some info on the Pontiac AFB's The Carburetor Shop / Pontiac AFB carburetors

Q-jets, Holley's, AFB's, Thermo-Quad, Demon, etc. all have their followings. I am a Q-jet supporter with regards to single carb/pontiac and AFB for dual carbs/anything. I don't have much experience with the Holley only because I had no need for one. 

You are somewhat limited in that you have a '64 intake which is for a square-bore carb, ie the AFB or Holley. To use a later Q-jet you will need an adapter that will mount the Q-jet to square-bore manifold. There are both the open style and tapered bore type adapters. It wiil raise the carb higher thus your air cleaner - which I don't believe will fit as the factory AFB has a smaller dia top as compared to the Q-jet, so you may need a new air cleaner with correct base to fit.

Sometimes the base of the carb is different than the mounting surface of the intake and this has to be checked. You don't want a carb hanging over the base where it should be sealed and is now exposed and won't work like that. It is a good idea to have a gasket that fits your manifold and use it to match the base of whatever carb you might consider purchasing - again, a carb adapter may be needed to make the 2 compatible if there is a mis-match.

Fuel inlet, throttle linkage, and any trans linkage have to be considered as well. If you can't fabricate or rather not, then this may become your problem even though the carb is a perfect replacement. There are however a number of linkages offered by aftermarket companies that can usually solve these issues, but it may still take some tweaking to work.

You can have your carb rebuilt or get another good core. Ebay is a good source and there is one on there right now for a 1967 Pontiac for $149 that appears pretty good. There are also others that are rebuilt, but kinda high priced in my opinion. The Edelbrock made Competition AFB's seem to get a bad rap, but I will find out when I put them on my car. Sometimes it is the lack of understanding and the inability to tune them that give any good carb a bad rap.

Your carb is said to be 575 CFM's which in my opinion is a little small for my taste given you have done some upgrades to your engine. I would not go any less than a 625 CFM carb and would prefer it to be a 750 CFM carb. You could also go the tri-power route as manifolds seem inexpensive, but the carbs and linkages are what seems to cost.

So, probably not much help in all this and I no doubt only confused you more in making your choice. :thumbsup:


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## tguggino (Aug 31, 2013)

Thanks Pontiacjim. All great advice. I completely agree we should get a higher cfm carb. We had our afb rebuilt. It is now back with the builder for "analysis". If they can't fix it, or e wn if they can, I am going to push for a bigger carb. 750 is my target. 

The Qjet sounds like a lot of adaptors and change of air cleaner. 

It would be great if anyone has experience with a 750 Holley or Edelbrock (or other) on a 64 389. Thanks again. 

If anyone has experience 


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## geeteeohguy (Feb 2, 2008)

Have run a Holley 750 'double pumper' mechanical on a '65 389 with an adapter plate. Ran very, very strong. A performance improvement over the AFB at the cost of fuel economy. A very sound choice (even the 700 CFM Holley would be good) if you want a simple, good functioning system that most people can work on. Holley's are the easiest carb to work on due to product support, simplicity, and popularity. Thinking about your situation, I wouldn't hesitate to run a Holley if your AFB jams you up too much. Keep us in the loop, and Merry Christmas, everybody!


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## 65gto (Aug 2, 2013)

One thing you might check out on the Carter is that you have the correct accelerator pump. The rebuild kits you get nowadays don't always have the right one. the kit I bought had one that was too short. Luckily I found a carburetor guru that helped find the correct one. Runs like silk now.


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## Rukee (Feb 8, 2007)

Does it only do it when hot?? If so you may need an insulator plate.


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## 64Original (Jun 21, 2017)

tguggino said:


> Good info. Thanks. If we wanted to go aftermarket. Would you recommend holly or Edelbrock?
> 
> 
> Sent from AutoGuide.com Free App


I would look at a quickfuel 680 for the 389 if going aftermarket. I would also talk to Sean Murphy of SMI Carburetors and see what he would recommend about rebuilding your original Carter. Sean builds the Quadrajets that Butler sells and I just ordered one from them for a 461 stroker we are building for our 64 GTO.





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