Gasket matching 782 Swirl head on the exhaust side?

414 Views 6 Replies 4 Participants Last post by Tonatom, 15 d ago

Tonatom

Discussion Starter · 16 d ago

Is it worth gasket matching the head on the exhaust ports? I already ported and matched the exhaust manifold so I'd assume I might as well do this but the ports get tiny 1" inside the head anyhow.

I'm not in the huge gains crowd, but a quicker spool up never hurt anyone.

Is it worth it?

Was planning on getting a 2.5" swing valve and down pipe. But due to $ constraints for now might just stick with the 2.25" swingvalve and exhaust. Other than open the exhaust up to a true 2.5 where it necks down over the rear axle, into a new muffler.

Thanks for any insight.

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Tonatom

Discussion Starter · #4 · 16 d ago

Glhs60 said:
To quote Shadow, the big gains are to be had aft the Turbo.

Buying, modifying or building a better swingvalve is very beneficial.

I like to start with a 3" downpipe with no neck down, right off the Turbo.

3" downpipe, even with a 2.25" swingvalve has worked well for me.

Thanks
Randy

Did you just adapt the 2.25 donut to a bigger pipe? I know fwd perf only specs their 3" downpipe for the 2.5" donut.

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Tonatom

Discussion Starter · #7 · 15 d ago

4 L-bodies said:
To answer your question, it will be a wasted effort to widen the exhaust port (port match) to the gasket limit. There is a gain bringing it up to the gasket limit on the roof of the exhaust port. When I port cylinder heads I'm gaining over 50 CFM on the exhaust side @ .500" and I'm not even at the gasket limit aside from the roof. Like others have stated, just make sure the exhaust manifold port is as big or bigger than the exhaust port on the head.

Thanks.

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