Headers question?

Question

here is my question when buying a gasket for a set of headers do u buy the gasket based on the header or the block, i have been told both by many mech., for example i have a new 350 with square ports but my headers are round, do i buy square ported, or round ported,no matter what i am getting copper gaskets if that helps

and if u could explain ur answer that would be nice

live in arkansas no inspections

also what problems will this cause having round ported headers and squared block

Answer 1

Your headers need to match the ports on the head. Otherwise you'll have turbulance at the mating surface.

It may not seem that big of a deal, but does make a BIG differance.

Answer 2

In my life time I've never seen rectangular tube headers. They are all round tubing. For a street use 350, 1 5/8 primary tube headers works best. Smaller primaries keep the exhaust velocity at it's maximum.
To prove to your self if the header flange fits your ports, trace a pattern directly on a Chevy small block header flange. You will see it fits your heads. Only the large inch 410 sprint car headers are a 1 3/4 primary. They have open headers and are pushing 910 horsepower on alcohol.

Answer 3

Best is to get the gasket that match the block as long as the holes on the headers are not covered in any way. this way carbon deposits will not build up on the exhaust ports. Also make sure your headers are OK for air pollution control in your state or you will have to remove to pass inspection, if a road vehicle.

Answer 4

If you have the correct headers they should match the square ports on your heads. If not you will need new headers.
The Gasket should be fitted to match the head. If you use the mismatched headers you will be restricting the exhaust and you may get and exhaust leak at the head.

Answer 5

fit them to the block