I'm relatively new to the second gen Olds V8s and I wanted to know if the 64-76 Olds 350 heads and the 77-80 350 heads are at all interchangeable? I've heard that the later heads (77-80) where lighter weight castings and that Pontiac Motor Division cast them instead of Oldsmobile. I have also read that they are more prone to warping/cracking according to some, but is there any reason they can't be used on an early block? I ask because when I went to order a gasket set for my 350 I noticed that the 77-80 gasket set is different and over twice as much as the 64-76. Other than the addition of EGR gaskets the only other difference I can see is one set of water passage holes are smaller on the early 350 head gaskets (of coarse the thickness may be different as well I can't tell that obviously). I have a '71 block in great shape but the heads need new guides at the very least. I know of a 77-80 (not sure of exact year) 350 which has heads that I can have. They had been redone only shortly before the motor developed a rod knock (this is my brother in law's engine by the way). Long story short he has decided not to fix the block and he told me I could have the heads if I can use them. Now, I'm sure they'll have less compression than my original heads but they are going in my driver '71 wagon so I am not worried about that. However, the difference in gasket sets got me wondering what else might be different and would this swap even be possible. Thanks in advance for any info you can give me.

Paul

 

Those late heads are terrible and will result in a large drop in compression. It may end up being as low as 7 to 1. Work with the ones that you have.

 

Earlier 350 parts including heads are still in decent supply. Don't use that late thinwall stuff, block or heads, if you have any choice at all. If the valve seats are pounded and worn from many valve jobs, your machine shop can open the seat areas for bigger valves like the W31 used. That is actually a good performance mod.

 

I understand they are not as good as the early heads (and the compression is appalling) but they won't be permanent. Eventually I'd like to build a 455 for it. However, right now I don't have enough money for that or to get my original heads completely redone (as I said before these are free!). So if I don't use these my car is off the road for the foreseeable future. I appreciate the insight, but all I really want to know is are they interchangeable? What gaskets should I use (64-76 or 77-80) for the swap? What other problems may I run into? etc... Unless someone has a free set of 350 heads they want to give me this is my only choice. Thanks again for any help.

Paul

 

I believe the 77-80 heads are emission heads, thus the CR drop.

I have to see how the gaskets and heads are different before I answer

 

The later heads and blocks are designed around 1/2" head bolts where the earlier heads and blocks use 7/16" head bolts. That could be part of the issue with cost of the gaskets as well.

I agree...stick with earlier heads.

 

they would work but it'll drop the compression which will reduce the power of the engine... use the head gaskets with the appropriate sized head bolt holes.

 

The difference in head bolt size would require re-drilling and tapping the the block for the larger bolts!
Using the smaller bolts would mess-up your torque readings!
Not worth it in my opinion!!

 

 

Partially open hole under the head of the bolt!

 

Hardened washers maybe?

 

3899696, group 0.293, washer, pkg of 10

 

They make the washers for SBF applications where they run 351W heads on 302's.