Getting heads straight

[Ugly1]

There may or may not be a thread on this but didn’t see one. Tried google and that was a bust. So here goes. 1968 -1970 ( the motor is a 1968) 350 cid Oldsmobile motor with a STOCK 4 bbl needing a rebuild. Frozen from sitting. Has stock #5 heads. Other than putting in hardened seats if I rebuild it was there a better set of stock heads then? Not looking for a holy grail set , but have had people drool at the sight of them. If rebuilt I may go .030 over on bore and stay at 10.75:1 compression.
Just throwing it out there.

 

[spidereyes455]

#5 are supposed to be the best flowing factory head. They did come in 2 flavors, small valve and large valve. Only way to identify which is which is to take them off and visually check the valves.

 

[olds307 and 403]

Really good chance they were/are factory small valve. Only the rare W31 came with 2"/1.625" valves. The #1 through 7A in 72 are all very close. You don't need hardened seats in Olds heads. Just get W31 valves with bowls opened at minimum. Without porting or bigger valves, expect sub 200 cfm of flow on the intake side. The new Mahle 10cc and 12cc DSS dish modern forged pistons will give around low to mid 9's to 1. Molnar and Scat make stock replacement forged connecting rods. The old school Speedpro forged flat top pistons are available, if it will clean up at .030" oversize. The Mahle and DSS are available in multiple oversizes to 4.155".

 

[Ugly1]

Really good chance they were/are factory small valve. Only the rare W31 came with 2"/1.625" valves. The #1 through 7A in 72 are all very close. You don't need hardened seats in Olds heads. Just get W31 valves with bowls opened at minimum. Without porting or bigger valves, expect sub 200 cfm of flow on the intake side. The new Mahle 10cc and 12cc DSS dish modern forged pistons will give around low to mid 9's to 1. Molnar and Scat make stock replacement forged connecting rods. The old school Speedpro forged flat top pistons are available, if it will clean up at .030" oversize. The Mahle and DSS are available in multiple oversizes to 4.155".

You can see it’s been sitting a day or two. Still in the (what’s left of it)original car. Was going to be crushed and saved it.they are definitely original to the motor I’d say.thank you.

 

[bracketchev1221]

Unless its going to be a daily driver I wouldn't even worry about hardened seats. That is a long term wear thing.

 

[olds307 and 403]

Unless its going to be a daily driver I wouldn't even worry about hardened seats. That is a long term wear thing.

Absolutely, not an issue with Oldsmobile heads even when they were daily drivers. Even if the valve seats are eroded, installing W31 valves will go into fresh cast iron.