350 Olds Build Questions

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Old Oct 9, 2017 | 05:53 PM
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350 Olds Build Questions

I have a 350 Olds 77-80 with a Comp Cam XE262h, full length hedman headers, holley street dominator intake, holley Ultra 650 DP, true dual 40 series flowmaster, 3:73 gears, posi, and hei. Pretty basic. I just purchased some rebuild 7a heads. I would like the compression higher but my budget is not agreeing. Pistons, rings, and boring it out would be nice tho. I think I’ll just put my heads on and call it a day. What gaskets should I use? & will I see any difference from the 3A heads that I have ?

*I wanted a weekend cruiser. Not too much but more than stock in my 1987 Cutlass Supreme.
Old Oct 10, 2017 | 06:27 AM
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I used the .028" Rocket Racing head gaskets. Unfortunately, they are now on back order. With a 62-64cc chamber and the thin gasket, I came out right at 9 to 1. Smitty from M&J Performance had .011" thick shim gaskets for around $100 a pair. Also .027" reuseable but around $150 to $200 a pair gor the superior Cometic gaskets. I know the 77-80 Olds 350 uses a unique head gasket. I can't remember if you use early head gaskets when you switch heads. Expect 8.5 to 1 with Felpro replacements but those heads are definitely better. Stock valves or any milling? CC them and go from there.
Old Oct 10, 2017 | 08:49 AM
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Originally Posted by olds 307 and 403
I used the .028" Rocket Racing head gaskets. Unfortunately, they are now on back order. With a 62-64cc chamber and the thin gasket, I came out right at 9 to 1. Smitty from M&J Performance had .011" thick shim gaskets for around $100 a pair. Also .027" reuseable but around $150 to $200 a pair gor the superior Cometic gaskets. I know the 77-80 Olds 350 uses a unique head gasket. I can't remember if you use early head gaskets when you switch heads. Expect 8.5 to 1 with Felpro replacements but those heads are definitely better. Stock valves or any milling? CC them and go from there.
I have to get them checked out to see if the valves are stock or if any milling was done. They were definitely rebuild but not sure on the specs. Bought them from a guy but you can never be sure. That’s a good question on what gasket I’m suppose to use...for my block or an earlier model block? The 9 to 1 compression with the thin gaskets...are there any issues I should worry about or go with a thicker one? Thanks for the info by the way
Old Oct 10, 2017 | 08:44 PM
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olds 307 and 403's Avatar
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You can use copper coat gasket spray on the shim gaskets but there should be no issues with iron heads. A Performer RPM intake is a better choice for your current and one with slightly more compression. The 650 is borderline too small as well.

Last edited by olds 307 and 403; Oct 10, 2017 at 08:47 PM.
Old Oct 11, 2017 | 06:38 PM
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spencer83's Avatar
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Originally Posted by olds 307 and 403
You can use copper coat gasket spray on the shim gaskets but there should be no issues with iron heads. A Performer RPM intake is a better choice for your current and one with slightly more compression. The 650 is borderline too small as well.
okay. Sounds great
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