# Which carburetor to go with?



## Jbozarth (Apr 4, 2020)

I've got a 67 pontiac lemans with a non-numbers matching 389 that is bored over 60 with a slight cam. I would like to go to an elderbrock carburetor but dont know cfs would be appropriate for it. Not sure what's on it now but was wondering weather a 650 cfs or 750 cfs would be better.


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## pontrc (Mar 18, 2020)

Good ole 800cfm quadrapuke


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## RMTZ67 (Mar 12, 2011)

I have a quadrajet on my Gto and a edelbrock on my camaro. Should have went with a quadrajet on the camaroBut if it broke dont fix it... so it stays.?


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## O52 (Jan 27, 2019)

Do you have the original manifold? Then the 650 would work best for a slightly stock engine. 750 with an engine with a cam and headers. But IMHO, the original Carter AFB would be better than the Elde. Hard to find one thats in rebuildable condition these days. If you have a spread bore manifold than a professionally rebuilt quadrajet is your best bet.


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## PontiacJim (Dec 29, 2012)

The smaller 650 CFM carb has smaller primary bores, and the 750CFM slightly larger. Both have the same sized secondary bores. Both are vacuum secondaries, so you can't go wrong with too much CFM's. The Edelbrock is a "square bore" base while the Q-jet is a "spread bore" base. Best to match carb to intake manifold base rather than get an adapter.

The smaller carb will provide quicker acceleration and be snappier, but may run out of steam if you like to spin the engine tight. The 750CFM will flow more at the upper end.

The Q-jet is typically 750CFM's. If you have a slightly larger cam, the 750 would be my choice. The Q-jet is preferred, but I have used the AFB as well and nothing wrong with them. The Edelbrock AFB can be "dialed in" easier than the Q-jet using one of Edelbrocks kits having jets, rods, and springs, and their instruction sheet. I have not used Edelbrock's version of the AFB, but have a pair of them for a dual quad application which is what I like the AFB for. I've simply used factory AFB's in my youth when they were easy and cheap to get.


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## ybodyfan (Jul 11, 2010)

You can go wrong with too many CFH's. For a near-stock engine, especially with a manual trans, used as a street DD where driveability is paramount, the smaller carb would almost always be the best choice.


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## HiVolts (Jan 27, 2020)

I run on Holley 750 on a 461 by Butler. Seems to like it well. Of course I only spin it to 5500 rpm max.


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## Lemans guy (Oct 14, 2014)

I use a quick fuel vacumn secondary 780 CFM, can dial in every circuit with screw in air bleeds, PVCR’s, and course main jets and secondaries, also vac secondaries have a screw fine adjustment......just like a Holley only better...4 corner idle, see through sight glasses, black coating for heat reduction......I like it on my 461, Butler cut the short block for me. They are really great.


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## Rodwine (Sep 7, 2013)

If


Jbozarth said:


> I've got a 67 pontiac lemans with a non-numbers matching 389 that is bored over 60 with a slight cam. I would like to go to an elderbrock carburetor but dont know cfs would be appropriate for it. Not sure what's on it now but was wondering weather a 650 cfs or 750 cfs would be better.


if you have any interest I could send you info on an Edelbrock Performer intake and 750 carb set up I recently removed from my 67 GTO. I decided to go back to the stock manifold and a quadrajet but the Edelbrock was running very well before I removed it


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