Q-jet to square bore

[akart]

Want to put on a Q-jet in my Edelbrock ESP square bore manifold. Question is:Would I loose much or any of my Q-jet power by using an adapter,spread to square. Or is it worth it getting a new spread bore manifold?
Money doesn't matter. It's performance and labor.

[Schroedum]

Any spreadbore manifold you get wont be comparable to the newer squarebore ones. That ESP manifold you have already is a notch above the standard performer. So I'd get an adapter plate for your intake if you wanted to stick with the Q-Jet.

[Mike C]

I'm counter to that. I do not like adapters in general and think they are a performance impediment. Losing the adapters lets you set it up with all OEM style parts from pump to carb.

On my kids project Jimmy we went with the Performer intake and a JET Stage 1 Q-jet with the divorced choke (stock style setup) and brand new OEM fuel lines so all metal on pressure side of the pump.

I you have a MUCH higher performance motor I think you can get an Edelbrock Performer RPM with spread bore still. I have a GM cast iron high rise spread bore manifold on my boat which is pretty much a clone of the LT-1 intake but without the square bore which is another option.

[akart]

Originally Posted by Mike C

I'm counter to that. I do not like adapters in general and think they are a performance impediment. Losing the adapters lets you set it up with all OEM style parts from pump to carb.

On my kids project Jimmy we went with the Performer intake and a JET Stage 1 Q-jet with the divorced choke (stock style setup) and brand new OEM fuel lines so all metal on pressure side of the pump.

I you have a MUCH higher performance motor I think you can get an Edelbrock Performer RPM with spread bore still. I have a GM cast iron high rise spread bore manifold on my boat which is pretty much a clone of the LT-1 intake but without the square bore which is another option.

Thank you for your input. I'll get the new manifold. I've had that off enough to make it an easy (not too) job. '86 body,'74 K20 frame,'83 running gear. 465 trans,205 transfer case. ORD spring lift and all new engine bolt ons.

[MikeB]

Jon Hardgrove at The Carburetor Shop probably knows more about carbs than anyone in the business. From an article quoting him:

"Jon warns that if you are changing from a square-bore carburetor to a spread-bore model, it's important to use the appropriate manifold. "Never use an adapter," he advises. "For maximum efficiency and performance, you want a manifold that's correct for the type of carburetor you're using."

And I like this comment:

For street-driven cars, Jon suggests spread-bore carburetors like the Rochester Quadrajet and Carter Thermoquad as "the way to fly." He says that some Holley four-barrels fall into this category, but he is not a big fan of Holleys. "Unless you have a racing application, spread bores work best," Hardgrove believes. "Assuming that you don't drive wide-open all the time, you're going to be running mostly on primaries and the spread-bore carb has smaller primaries."

[akart]

Originally Posted by MikeB

Jon Hardgrove at The Carburetor Shop probably knows more about carbs than anyone in the business. From an article quoting him:

"Jon warns that if you are changing from a square-bore carburetor to a spread-bore model, it's important to use the appropriate manifold. "Never use an adapter," he advises. "For maximum efficiency and performance, you want a manifold that's correct for the type of carburetor you're using."

And I like this comment:

For street-driven cars, Jon suggests spread-bore carburetors like the Rochester Quadrajet and Carter Thermoquad as "the way to fly." He says that some Holley four-barrels fall into this category, but he is not a big fan of Holleys. "Unless you have a racing application, spread bores work best," Hardgrove believes. "Assuming that you don't drive wide-open all the time, you're going to be running mostly on primaries and the spread-bore carb has smaller primaries."

Thank you very much for your input and advice. "I Believe" and I will get a new correct spread bore manifold for my Quadrajet carb.

[MikeB]

Originally Posted by akart

"I Believe" and I will get a new correct spread bore manifold for my Quadrajet carb.

Hallelujah!