Head and Intake Question

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Mar 10, 2022 | 05:19 PM

vht

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Head and Intake Question

I was going to port my 862 heads and install 2.02 valves. A friend has a set of 863 heads off a 09 chevy truck, I'm not familiar with the later heads co I was wondering if they are any better and valve size if anyone knows. I'm going blow thru and have a Holley intake. The intake is supposed to be cathedral but looks more like a rectangular port, he says his heads are 2 1/2 x 1 1/4, mines 2 1/2x3/4, just wondering if I can match the ports? Are the heads worth using? They will be ported also, just thought if they had 2 in valves, that would be a plus. One thing that just came to me, the later heads have different bolt lengths, don't they? That would kill it because I've done bought head studs.

Mar 10, 2022 | 06:18 PM

vht

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I have done a bunch of research and all I've found out is, thicker decks and a better alloy and from what I've found out, they shouldn't of been on a truck motor. Any help here?

Mar 10, 2022 | 06:42 PM

G Atsma

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From: Central Cal.

4863 heads came on the supercharged LSA engine, with 72cc chambers and rectangular ports. They only fit 6.0 and larger engines. No 5.3's

Mar 10, 2022 | 07:40 PM

vht

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Cylinder can't be notched to clear the intake valve?

Mar 11, 2022 | 12:43 AM

G Atsma

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From: Central Cal.

Quote:

Originally Posted by vht

Cylinder can't be notched to clear the intake valve?

That will cause severe shrouding of the valve. Not a good idea.

Mar 11, 2022 | 06:40 AM

99 Black Bird T/A

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Notching top of cylinder block for valve clearance was pretty common on Big Block Chevy 396/454's back in the day. I've read notching could help one to get ~25 to 30 hp on a BBC with the bigger valves etc.

I'd step up to bigger bore LS block like at least 4 inch 6.0/LS2 or a 4.065 bore LS3 block if wanting the big 2.165 valves. More cubes and less shroud of big valves!

On the typical aluminum block LS that has iron sleeves for cylinder liners - no idea how well notching would work. The notch for a 2.165 valve on a 3.80 bore might be pretty deep into the cylinder wall liner. Might work OK on an iron block LS etc.

Mar 11, 2022 | 04:34 PM

vht

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I have an iron block but as was mentioned I was thinking about the shrouding also. I wish I had a 6.0 but these LS engines are getting to be big dollars. Guess I'll go with the original plan and port the 862 heads and install 2 or 2.02 valves.