manifold/carb compatability

bill dedman · 09-01-2009, 11:24 PM

This is a general question abiout the compatability of square-bore (Holley) 4bbl carburetors and intake manifolds that will accept a spread bore carburetor.

Is it possible to bolt a square-flange 4bbl Holley carburetor onto a manifold that will also accept a spread bore (Quadrajet) carburetor?

I'm wondering if one manifold could accept both carburetor flanges, or would the distance between the outside of the holes in the manifold that would line up with the spreadbore throttle bores, be wider than the Holley square flange?

In other words, can both spreadbore and square Holley flange carbs both be used on ANY one manifold without an adapter?

Any information will be appreciated.

Thanks in advance.

Mark Yacavone · 09-02-2009, 12:54 AM

Yes. Did it today in fact. Of course you have to check the gaskets very closely.

bill dedman · 09-02-2009, 08:32 AM

Thanks, Mark. I was afraid the openings for the throttle blades in the manifold were so "wide" that a Holley "square" carb flange wouldn't cover them, side-to-side.

Since this works, it makes me wonder why they make two manifolds (aftermarket), one for each carb. You'd think they'd just make a "one size fits all" manifold with both sets of hold-down bolts (speadbore and square.)

Maybe they do... and I was just unaware of it.

I appreciate the good info, Mark!

09-01-2009, 11:24 PM	#1
bill dedman VIP Member Join Date: Feb 2002 Location: Conway, AR Posts: 1,739 Likes: 0 Liked 6 Times in 4 Posts	manifold/carb compatability This is a general question abiout the compatability of square-bore (Holley) 4bbl carburetors and intake manifolds that will accept a spread bore carburetor. Is it possible to bolt a square-flange 4bbl Holley carburetor onto a manifold that will also accept a spread bore (Quadrajet) carburetor? I'm wondering if one manifold could accept both carburetor flanges, or would the distance between the outside of the holes in the manifold that would line up with the spreadbore throttle bores, be wider than the Holley square flange? In other words, can both spreadbore and square Holley flange carbs both be used on ANY one manifold without an adapter? Any information will be appreciated. Thanks in advance. __________________ Bill

09-02-2009, 12:54 AM	#2
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,418 Likes: 2,582 Liked 4,453 Times in 1,694 Posts	Re: manifold/carb compatability Yes. Did it today in fact. Of course you have to check the gaskets very closely. __________________ We are lucky we don't get as much Government as we pay for..... Will Rogers

09-02-2009, 08:32 AM	#3
bill dedman VIP Member Join Date: Feb 2002 Location: Conway, AR Posts: 1,739 Likes: 0 Liked 6 Times in 4 Posts	Re: manifold/carb compatability Thanks, Mark. I was afraid the openings for the throttle blades in the manifold were so "wide" that a Holley "square" carb flange wouldn't cover them, side-to-side. Since this works, it makes me wonder why they make two manifolds (aftermarket), one for each carb. You'd think they'd just make a "one size fits all" manifold with both sets of hold-down bolts (speadbore and square.) Maybe they do... and I was just unaware of it. I appreciate the good info, Mark! __________________ Bill