Who all here Gasket matched intake and Heads ?

[Transamman25]

I was just told by a pretty famous porter , its Bad ! He said the intake should Bottle neck into the head. Has anyone ever heard of this , if so please explain why !

[ksmyss]

you want the intake ports slightly smaller than the head ports that way the flowrolls over the lip and into the heads. if its the other way around the flow will hit a lip on the head and cause turbulance.

[jakesz28]

If both were cut to match the gasket when the gasket compresses a little it will stick out into the port.

[James Montigny]

Head and intake should match each other, not the gasket.
Gasket can be trimmed if it protrudes into the path, although the pushrod pinch on LT1s
generally determines the max runner size, which should be smaller than a standard gasket.
Much larger and it will actually reduce velocity and decrease performance
The manifold portwork I've seen allows a .100" taper from head to plenum.

[Enthusiast]

It seems logical to me.

If the manifold bottle necks down just a little, the air will be accelerated, right as it enters the head, and dont forget we are only talking about a difference of a fraction of an inch.



If it was the other way around you would loose velocity as the air came closer to the head.

Some of the best DIY mild porting jobs Ive seen have involved next to no gasket matching.

[chevy42083]

Are you an artist, or do you just color inside the lines