midnightleadfoot

Hello...
I spent my years on Pontiacs and chevy's.. not up on the olds engines..


My question is what are the difference in heads that can be used on an olds 350..
Is there a list .. I've seen over the years forums threads with I got a 400 with 3x or 6x /etc (iirc) but no clue as to what that all means..


my plan is to upgrade my mid 70's smog 350 next year.. as this year/season it will be the c-10 truck.. That gets all the big love ($$) .


Is there a listing with valve sizes ,port sizes, chamber sizes..
It be nice to swap heads to up the compression from the claimed 8 to 1..
to something a tad better..


Not sure if the edelbrock heads are ideal for a 350 or not.. weigh'n my options..


For a street car that not really be see'n north of 4500-5000 rpm..
Are the 307 heads an option? for that low end and area below the curve/peak..
Again totally green on the olds engines so don't shot me..
Thanks

boese1978

I have the aluminum heads- they are more for a big block- takes a bit of machine shop work- fuel pump clearance, there are PS pump issues to be addressed, milling on the combustion side and the intake side so all fits the way it should, to make them work on my 350.

cdrod

Midnight:
Mid 70's Olds 350 motors used a larger combustion chamber head with a small-ish dish in the pistons. Installing earlier heads ('68-'72) can easily bump up the stock 8:1 compression ratio up to around 9:1 with the right head gaskets. I have a set of #7 heads from a '71 Cutlass that are bare castings and will need new valves; I also have a set of #7a heads from a '72 Cutlass that are complete with stock valves and springs. Let me know if you are interested in them.

cutlassefi

As mentioned, the early heads (5, 6, 7a) all have the 68-70cc combustion chamber. Mid 70's will have a 79 or so cc chamber. Easy swap is to drop a set of early heads on the mid 70's short block. Only other difference is valve sizes but most will be the same unless it's a W31 or has been modified.
And for the record, all small block Olds heads are numbered, 2, 4, 5, 6 and so on. Big block Olds heads are lettered, A, B, C, E, G, K etc. D's, H's and F's are very rare.

midnightleadfoot

Your questioning of my #x and Pontiac and odd..
Are the Pontiac engines the same as olds?? no. So why would I assume that the numbering system would mean the same thing..


I asked the question So I'd get correct info. not me assuming that olds used the same system to mark castings as Pontiac.. of vise versa..


sbc gen 1/2/3 sb2.2 r07 r09 ls lt can look at and know..Pontiac I mostly can look at and have a good guess but still have to look up castings.. to be 100% sure.. Fords are totally new to me.. and no time to get up to speed.. olds is new to me..
Is there shame in that?

cutlassefi

This is what you said;

"I've seen over the years forums threads with I got a 400 with 3x or 6x /etc (iirc) but no clue as to what that all means.."

No shame in not knowing Olds but it sounded to me like you didn't know what the Pontiac head ID system was. If you meant it another way then you may want to clarify that.
Olds head ID is as described with most big block heads being 80-82cc as cast. All '64-'90 Olds have the same bore centers and bolt pattern, with the main difference in a small vs big block being deck height and main bearing size.
If it's still up, www.442.com is a decent site in which to get info like this.

Hope this helps.

olds 307 and 403

Here is an example my 76 350 had the 8 to 1 compression. By adding a set of 1970 #6 heads which were rebuilt and milled, they CCed at 62-64CC. Add in the factory dish 14CC pistons, which can be as much as .030" in the hole. Since they sit around the .025 to .030" in the hole, I bought the Rocket Racing .028" head gaskets. Measure it all together and you get right around 9 to 1. The early 5A 307 heads would yield similar compression but could use bowl work and 350 valves for anything above 4000 rpm. I had them on a 76 350 in two trucks, they performed well at idle to maybe 4500 rpm. On my 94 Z71, it would outperform any 5.3 stock trucks with the same trans and gearing. When I added the 454 TBI it would plain kill them but I had to switch back due to issues with sensors. Remember this was a stock 76 bottom end, lousy 204/214 cam, stock 5A 307 heads, A4 307 aluminum intake, factory 454 TBI to Qjet manifold adapter and Sanderson shorty headers. This was the sbc stock swirl port tune which needed the timing advanced 10 degrees to even run the Olds 350, 20 was better, 4L60E with a 1400-1500 stall and 3.73 gears with tall 265/75R16 tires.