#5 heads on late Olds 350 (1977)

[foxtrot]

Mill them at least .020", add 2.07/1.625 valves with bowls opened up. Add matching springs to a better cam, definitely needed and maybe machine the guides for positive seals. Use the Rocket Racing .028" head gaskets with the milling you will be right around 9 to 1, a good upgrade allowing a cam in the 215 to 220 range.

Good solution.

Since this solution will be utilizing the stock valve-train for the most part, you'll also need to check your pushrod length..

 

[olds307 and 403]

Good solution.

Since this solution will be utilizing the stock valve-train for the most part, you'll also need to check your pushrod length..

I am doing this myself very soon except 1.56" exhaust valves, heads were bought ready to go, a better stock 76 bottom end and a 217/223 custom cam on a 112lsa.

 

[BigGeorge]

So it is not 123 easy!!! That sucks. I was thinking a head swap would have been beneficial but now I'm hearing that the rest of the valve train may not even hold up. I was really not wanting to purchase another core. If I had to purchase another block I would want a 403 or 455. However, I'm not ready to go that deep. I think I will just keep what I have.

Then it goes back to I could do a lsx or ls1 way cheaper... Hmm...

 

[olds307 and 403]

As long as you keep RPM reasonable, it will live.

 

[olds307 and 403]

Those same early heads would bolt right on, after opening up the head bolt holes and one dowel to 5/16", on a 403 block and give around 9.3 to 1 if you do hurt your 350. Just keep it 5000 rpm or less and it will live just fine.