Just trying to make my caddy a bit quicker on the road. It's got the olds 350 in it and I'm looking at putting more power to the heads. Luckily for me, I've got olds engines from the early 70s up till the mid-'80s that I could pull parts off. For now, I am looking at heads. Which heads would provide the most potential for power (for the cheapest cost/effort).

-Chris

 

The 1972- earlier heads have smaller combustion chambers than the 1973-up heads. The exhaust flow better as well.

 

65-67 2, 3, and 4 heads will have the smallest chambers. You’ll have to drill the head bolt holes out to 17/32 on any of the 65-72 heads. #3 and early 4 will need to have the pushrod holes drilled out with a tapered drill bit (Harbor Frieght ones work well enough) due to the different lifter angle and the pushrod sometimes will hit the guide hole. Also, factory gaskets are .017”, replacement gaskets are .042”. Cut the heads .025” to make up the difference so you’re not losing chamber volume from the increased gasket thickness.

 

Without swapping the peanut cam, adding heads that will gain you .5 to 1 compression won't do much. Your 3A heads are crappy and crack prone, so it does make sense to use earlier heads if doing any porting or machine work. Consider dual exhaust to add some power. Is your Cadillac a factory analog fuel injection?