Cutlass Fan

What are the differences between the #1,2,3 & 4 heads on the 330. I saw that they supposedly had a different number head in each year of production.

olds 307 and 403

#1 had rocker shafts and a 45 degree cam angle. #2 had 3/8" rocker studs, same angle. #3 and #4 had the same 5/16" rocker set up as all later Olds V8's. #3 had the 45 degree cam angle, #4 the 39 degree cam angle like all Olds V8's to 1990.

svnt442

The heads don't determine the lifter bank angle, the block does.

olds 307 and 403

Yes, but it means there may be push rod interference if they are put on later blocks.

joe_padavano

^^^This. There are minor variations in the pushrod holes in the heads due to the lifter bank angle.

edzolz

Also, supposedly, the #4 heads had smaller combustion chambers.

Redog

The #4 heads I have at the "WG" heads which are the hi compression heads Not sure if all #4 heads are Hi-Comp heads

joe_padavano

Every single 1964-1972 SBO head has chambers in the 60cc-66cc range. Variations are more due to manufacturing tolerances and how many times the heads and valves have been cut than due to any design differences. "High Compression" was achieved by changing the piston dish, not the combustion chamber. The no. 8 heads from 1973 were the first SBO heads with different size chambers (approx 80 cc).

Octania

Nice summary.


"HC heads" is probably Chevy-centric voodoo. Olds used variously dished pistons.

Cutlass Fan

Thx for the info. I take it they all have similar flow and that it is similar flow to 350 heads.

olds 307 and 403

My understanding is yes. Same size valves as regular 350 heads and similar ports.

Cutlass Fan

Good to know, thx.

oldsmobiledave

I disagree with the cc range. It is 64-69 cc not 60-66 cc. Only the #4 heads are 64 cc the others are 68-69 cc as cast.

joe_padavano

Maybe as-designed, but not as-cast. Every Olds head I've ever seen has an as-cast chamber that's larger than the advertised numbers. Until someone performs a survey of chamber volumes with a statistically valid sample size, I'm not going to worry a lot about published numbers. The reality is that a couple of cc's of difference in chamber volume will not be measurable in performance.

Obviously, anyone who is building an Olds motor for performance should properly measure and set chamber volumes, piston heights, dish size, etc, etc. For the vast majority of people who simply want to bolt heads onto their stock or nearly stock motors, they will never see the difference in performance with any #1 through #7A heads. Normal production tolerances everywhere else (not to mention using FelPro blue gaskets) will far outweigh a 4cc chamber difference.