Compression on pump gas

[lukecp]

I am still thinking of adding some new heads on the rebuilt 350 in my truck this summer. It was a stock rebuild, with a RV cam and cast flattop pistons. So, it should have around 8.5:1 compression right now. I have narrowed down the head choices to either a set of World Products S/R Tourqer heads, or a set of Vortec heads. The S/R Torquer heads have 67cc combustion chambers, and doing a little math, that would give me around 9.5:1 compression. The Vortecs have 64cc chambers, which would put me in the 10:1 range. So, could i run the 9.5:1 engine on 89 octane gas? And would the 10:1 engine require anything higher than 91 octane? I have a RV cam, a 270/280 cam, so would that help bleed off a little extra compression? Would my stock pistons be able to handle that much compression? The motor was rebuilt about 14k ago. According to Desktop Dyno 2000, i will be making in the neighborhood of 350 HP and 410 TQ with either set of heads.