Slowly, much like the repairs to 2511, my engine is being assembled, and my engine builder posed a question I do not know how to answer.

I am using the 4-barrel CHI heads and blue thunder intake, 404 stroker, GTS tri-y headers.

Exhaust ports on my heads are not CNC machined but remain as cast.

Question:

What sort of heads to headers port matching should be done?

None? Match to gasket? Or???

Any wisdom you can provide is appreciated.

Thanks,

Larry


Sent from me using a magic, handheld electronic gizmo.
Original Post
The flanges on the headers should be made to match the gaskets, which match the heads.

IF you have selected a camshaft that maximizes the flow characteristics of the ports, then match the gaskets on the exhausts.

IF instead you have selected a "sane" street cam, then don't bother.

It's far more important on the exhaust to match the size of the tube to the flow of the exhaust port.

If the flow numbers on the heads show say 330 at .630, 220 on the exhaust and you put in a hydraulic lifter cam that is .580 lift, again, don't bother. No matter what you do, the heads aren't working anyway.

It's pretty difficult to maximize the flow of the headers at the flanges. All sorts of compromises had to be made just to attach the tubes. Many turn the wrong way or the radius is too tight, etc.

Even if the builder got some of them right, usually half of them are wrong.

Matching the gaskets? "Much ado about nothing". Save the money.
FWIW, Larry- I agree with Doug. Head and intake manufacturers do the best they can on port sizes and orientation, using dyno runs and all when building their products. Then hot-rodders with die-grinders promptly alter the ports to match someone's stamped gaskets! Note also that gasket openings vary noticably from different sources. All I usually do is make sure the header flanges are flat, as welding distorts the finished product.
quote:
Originally posted by Bosswrench:
FWIW, Larry- I agree with Doug. Head and intake manufacturers do the best they can on port sizes and orientation, using dyno runs and all when building their products. Then hot-rodders with die-grinders promptly alter the ports to match someone's stamped gaskets! Note also that gasket openings vary noticably from different sources. All I usually do is make sure the header flanges are flat, as welding distorts the finished product.


I'd recommend using the Fel-pro header gaskets.
These are for the aftermarket aluminum heads. My header flanges match these.

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