Carburetor Adapter Question

[Lazerwolf]

Doing a little research on tuning my carburetor, I found this article.

http://www.hotrod.com/how-to/engine/1202phr-10-biggest-carb-mistakes/

One thing that struck me odd was a statement in there on carb adapters.

Edelbrock’s Stinson says: “If the customer has a spread-bore like a GM intake that a Q-jet came off of, we’d recommend a number 2697 adapter kit.”

I currently run an Edelbrock square bore carb on an Edelbrock Performer manifold (spread bore), as probably many of us do. The adapter he is talking about is a square bore carb mount to spread bore manifold. I just use the 1/8"(?) metal adapter plate, with a 1/2" composite spacer. I'm well aware of the heat transfer, so please ignore the aluminum/composite issue. My question is with the vacuum sucking the air/fuel mixture down into the manifold, would you really get any benefit from this type of adapter? It would seem like better airflow in theory but it's not increasing volume of air or fuel. Would just like your opinion on this. Just a gimic?

 

[Meep-Meep]

There is something to providing a smooth path both in and out of the carb but I'm pretty sure you won't notice much difference if all you did was pop the adapter on.

 

[Lazerwolf]

Ok, thanks. That's what I was thinking but just didn't really understand the logic behind it. Maybe you gain 1 HP or get 1/10 MPG better or something odd like that, but they never state any reason. I'm a long way from a tuning expert and I know there is a lot of knowledgable folks on this site.

 

[jimt1971rr]

One issue that you can run into when using one type manifold and the other type carb is the location of the mounting studs. In the article, the spread bore manifold is actually setup to potentially handle either type carb. You may notice that there are two different bolt holes in each corner. If you are running an O.E. manifold and want to switch carb design, the bolts won't line up. I personally ran a T.Q. on a square bore manifold and, if I didn't have the adapter, not only would the bolts not line up, but the secondaries wouldn't open due to the smaller openings in the manifold.

 

[mopar 3 B]

One issue that you can run into when using one type manifold and the other type carb is the location of the mounting studs. In the article, the spread bore manifold is actually setup to potentially handle either type carb. You may notice that there are two different bolt holes in each corner. If you are running an O.E. manifold and want to switch carb design, the bolts won't line up. I personally ran a T.Q. on a square bore manifold and, if I didn't have the adapter, not only would the bolts not line up, but the secondaries wouldn't open due to the smaller openings in the manifold.

I also match the adaptor to the manifold and use the TQ thick gasket under the carb.