I have a 454 that I am going to build and am looking at all options (for the street). The block is a 1974, but the heads (336781) Large Oval port heads, Open Chamber, are 1977.
The RPM Air-Gap 2-O states it is designed for Chevy V8's (396-502) with large oval port Cylinder heads (1975 and earlier). The 336781 heads were made from 1973 to 1985, I'm confused.

Thanks for any help,
Fred.

the heads you have are just the standard oval port heads (not peanut port or rectangle)......they are rated at 114cc chambers open of course as you stated.

bottom line is the rpm air-gap or any other oval port intake will work just fine.

That may just be a cover your ass statement from E-brock,as that manifold has no EGR provision.Thats just my guess though.

You might cc the heads if possible b/c they vary ALL over the place..

pdq67

Thanks guys,

pdq67,

The engine shop that I go to, told me the same thing. He stated that most of these head seem to be closer to 118 cc or close to that value. I guess I need to cc them tomorrow. I will let you (and anyone else) know what size they turn out to be.

Thanks,
Fred.