Looking at Fel Pro HS 8364 and 8506, friend of mine didn't think it’d matter which to use. Personally, I recommended 8506 (as its Olds specific, especially with the dowel hole), but he went ahead with the 8364. He said the coolant passage holes were the same, sk it should be fine. Two weeks later he tried to run it but had coolant mixed with oil in the oil pan. (Overfilled oil so he thought.)

The question is, is it the head gasket causing the gigantic coolant leak? That would be my answer, but we’re both about the same in terms of mechanical know how. We have done rebuilds, had our books, proper torque spec, etc, but this is a new one. Also apologize for my test question format, just wanted to be as descriptive as possible. I have the 80 Delta 88 350, he’s got the 77. Same block, just two different part numbers and two different outcomes. Thank you all.

 

8364 is a Chevy gasket and is completely different than any Olds gasket. I don't think you'd even be able to install it. Is that a typo?

 

Thaaaat kinda gives me the answer there, ha. He got a gasket set from AZ and the part number on the box is 8653, not 8364. My apologies.

 

8653PT looks like it fits 80 and newer Olds 350.
1977 350 should be a 8506PT Not sure what the difference is.

Why didnt he just have them look it up for his year ???

 

Any differences between those sets won't matter. There's only three real variants of Olds head gaskets for 64-90. Pre-77 use 7/16 head bolts, 77-later use 1/2. The 403 has a huge bore so it has a larger opening and smaller bridges between the cylinders. Any other differences aren't important.
Oil/coolant mix shouldn't happen from overfilled oil. That would just cause the oil to get whipped.
It IS very easy to have a leak at the corners of the intake manifold and have coolant leak into the lifter valley. There aren't many places to mix oil and coolant other than that.

 

[QUOTE=oddball;1626172]Any differences between those sets won't matter. There's only three real variants of Olds head gaskets for 64-90. Pre-77 use 7/16 head bolts, 77-later use 1/2. The 403 has a huge bore so it has a larger opening and smaller bridges between the cylinders. Any other differences aren't important.
Oil/coolant mix shouldn't happen from overfilled oil. That would just cause the oil to get whipped.
It IS very easy to have a leak at the corners of the intake manifold and have coolant leak into the lifter valley. There aren't many places to mix oil and coolant other than that.[/QUOTE

and that was my question, WHERE would the coolant be coming from? We rtv’d the intake at the front and rear, and truthfully I can’t think of anywhere else it’d be mixing from. Tried to pressure test, but theres a pinhole leak in the radiator, so it won’t hold pressure.

 

i want to say he did, I wasn’t with him when he ordered though. …i dont often trust stores for this reason, as people still get things mixed up unfortunately even with the right info.