Carter AFB 9636

[runner74]

Hello

I have a 74 Roadrunner 400. My question is about the carburetor. After doing some research if appears it originally came with a Carter 6457s 800CFM carb.

When I got the car it had a Carter AFB 9636a 1707 (Looks to have an adapter plate) Competition series. Question: Is this a good choice for this engine at only 625CFM? It seems to run ok except for a little stumble under light acceleration from a stop, and of course the hard start heat soak when hot. So I plan on putting in a phenolic spacer (Tans Dapt 2446 or Canton 85-154) and just wondering if I should dump this carb for another? Has anyone tried Autoline C6073? (Similar to OEM)

Any suggestions welcome.

Thanks

 

[rumblefish360]

It's OK for a driver. Just tune it up!

The OE carb was a TQ. The primaries were approx. the same size as the AFB.

 

[idrivemopar]

Something to keep in mind, with the way thermoquads are rated, and as stated below the ratings vary by source. Some folks have gone over to modern Edlebrock Thunder series carbs. Also keep in mind whether your motor is stock or modified, as higher compression bigger cam will make requirements different than stock. As rumblefish stated, you might try and tune or rebild the carb before jumping into something else first. Also, thermoquads are hard to come by these days.

From the thermoquad sticky, and if you want to read all about it, its here, http://www.forbbodiesonly.com/moparforum/showthread.php?38460-Thermoquad-Guide
The Thermo-Quad was available with two primary throttle bore sizes, 1-3/8"
and 1-1/2". Flow ratings (CFM) vary depending on the source, but
the TQs with the 1-3/8" bores are listed as 750-800 CFM and those with the
1-1/2" primary throttle bores are rated at 800-850 CFM. All TQs have the
2-1/4" diameter secondary throttle plates. The primary bore size depended
on application.

 

[runner74]

Thank you both.

Very interesting read idrivemopar

It is a bone stock driver. Just want it to be at it's best if you know what I mean. I want it to run as good as it looks.

 

[runner74]

Oh, another question? Do I get a phenolic spacer to put under the carb or directly under the carb adapter? ( I am assuming there is an adapter spread bore to square?)

 

[idrivemopar]

So, the thermoquads absolutely need a phenolic spacer because of the center section of the carb is plastic, not sure about the AFB requirement. Yes, they do make spread bore to square bore adaptors, I used to use one when I had my holly 600 on the car back in the day.

Looks like you should be able to get the gasket, 1/4 inch thickness, open center, at autozone, http://www.autozone.com/fuel-systems/carburetor-fuel-injection-gasket-and-seal/mr-gasket-1-4-in-thick-4-bbl-open-center-skin-packaged-carburetor-base-gasket-for-carter-afb-edelbrock-performer-or-holley-carburetors/153327_0_0/.

The spread bore gasket/space I use is a Felpro 60273, its a 1/4 inch thick.

 

[rumblefish360]

All MoPar carb gaskets are of the "thick" verity. If you "Need" the adapter under the AFB/AVS for your spreadbore intake, then use the thin gasket first, adapter, thick gasket, then carb.

Edelbrock sells thick gaskets. I *think* there only in a Holley spacing. I may be wrong. Do so check! They do not sell thick TQ gaskets. I would not bother with the adapter when making use of a Edelbrock or OE Carter on a spreadbore intake since the bolt pattern is on the carbs for ether styles.