Thread: Carb Question

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Its time to change the carb on a 383 SBC. My son inlaw owes me a carb and has two. Question is, cfms being equal, street driven, Spreadbore or square?

Originally Posted by 53 Willys

Its time to change the carb on a 383 SBC. My son inlaw owes me a carb and has two. Question is, cfms being equal, street driven, Spreadbore or square?

it depends on your intake. if a Q-jet came off of the intake then you will need the spreadbore. if you don't have a Q-jet intake the you will need the square carb. on a Q-jet intake the back 2 holes are bigger than the front 2. you can use an adapter. if you need to.

E-Brock Manifold. It can accept both

the eddy should only be able to accept a square bore carb, but if for some reason you are right. the difference is a square bore has equal size primaries and secondaries, while the spread bore has small primaries and large secondaries, that means you can get a little better gas mileage when just puttin around with the spreadbore, and open her up and get some good get up and go when you need it

Originally Posted by 53 Willys

E-Brock Manifold. It can accept both

don't see how you could put both carb. on same intake unless you used an adapter of some kind. the Q-jet base is bigger than the reg. holly. but i learn something new everyday

This is the manifold

http://store.summitracing.com/partde...1&autoview=sku

Originally Posted by 53 Willys

This is the manifold

http://store.summitracing.com/partde...1&autoview=sku

still looks to wide for a reg. holly.

Its has a 600 cfm Square on it now. And it is tapped for both patterns

Originally Posted by 53 Willys

Its has a 600 cfm Square on it now. And it is tapped for both patterns

like i said, learn something new everyday.

The Holley will bolt on , but it won't quite run right without a square bore spacer.

Originally Posted by NTFDAY

The Holley will bolt on , but it won't quite run right without a square bore spacer.

every intake i've seen came with a spacer. if you dont use it you'll have a vac. leak.

I think to answer my own question and the fact that this is my son inlaw, I'll try the speadbore first and see. If I dont,t like it I will play the part of Father inlaw and "Borrow" the other
Thanks for the replies