Check out my car and talk to me about 318/340 swap

moparmat2000 said
How far in the hole were those 273 pistons at TDC? I am betting they were much much closer to the top of the deck than your run "o" the mill 318. I have 2 of these 318s the 77 one the piston TDC was .080" in the hole the 74 was .100" in the hole at TDC. If his teener pistons TDC at around that, with 72cc 360 heads, your really dropping that CR. Mid 7s on CR.

You would be surprised how much it can change by just changing the head cc. Do you have any numbers to share on that 273? What was the piston depth in the holes at TDC, what were the CCs of the heads you used?

273 2 barrel pistons are only .020 to .040 in the hole. My 273 had 10.5 TRW forged pistons. I only brought it up when talking about port and valve size. You guys are missing my point completely. You don't know the size chambers you are talking about, and you are fixated on compression. If you are building from scratch that is all and well and good, but that is not what we are talking about here. You must match your combination. How do Magnum heads work so well on a 318 with their air flow about the same as 360 heads? Think it through.