195 cu. in. Compression Ratio
 

I have a 1961 DS code, low-compression, 1bbl, 4-cyl engine. According to the documentation that I can find, Pontiac used the same head for both the low and high compression version of this engine and adjusted compression with piston dish. I found receipts from when the previous owner had the engine rebuilt, and it shows that Sealed Power 288P flat top pistons were used. I guess it's safe to say that I have at least 10.25:1 CR since it also shows the head was milled, even if a thicker than stock head gasket was used?

Correct, dished pistons yielded somewhere around 8.6 compression. The flat tops were around 10.25. If head & or block was milled, it would go up from there. If you can find a 1963 #9770979 head, that would put you back into the 8.6 ratio area..... A 1963 #9770980 head would be in the range of 9.9 ratio. But, this all depends on how much the block/heads were milled. There were a lot of things that went into the higher HP engines, Cam specs were different as were Distributor settings. Dual springs on the valves. Larger exhaust pipes, etc, etc. 1bbl carb Verses 4 bbl. There were also over the counter stuff like cast iron hedder's & aluminum intakes.

A 980 head might be a issue as the center exhaust port bolts are wider.Tom

True, that was the performance head at the time. His best bet is a 979 head. Lowers the compression back into pump gas range & all the Tempest manifolds will bolt right up.

Actually a 62 127 head had the same size valves as the 980 but std bolt location on the center.IMO a 716 head would be a better choice.Tom

Actually, I don't mind the higher compression. It's a fair weather driver and pump 93 is plentiful here (near sea level). The machine shop ticket also states that the cam was sent to Effington Regrind in Effington, IL for a regrind. It provides no information on the specs of the regrind. It certainly has a smooth idle, so I assume it was to stock specifications.

I know the V8's moved to pushrod oiling in '64 for some, and '65 for all engines. What is involved in putting a '65+ head on this? I realize the intake manifold flange is different, but anything needed for the valvetrain oiling?

You can take any 65 & up head & it will bolt right on with no issues for top end oiling. Exhaust is no problem. The issue is the intake is different. You would have to take a V8 aluminum manifold & have it cut up & welded up to make a 4 cylinder manifold. Then a 4 bbl carb with about 450-500 cfm..

One issue with the newer head is the valve angle is different & the valve reliefs in the sealed power piston are for the earlier head valve angle.

Thank you!

When I rebuilt my 4 cyc I went to pushrod oiling.Used 65-66 rockers.No issue at all.Tom

I contacted Effingham Regrinding and he pulled the records and confirmed that the camshaft in my engine was reground to the high compression 1bbl/4bbl specs.