California Bill's Speed Manual says that taking .0625 from a 270 head got 9:1 compression with Venolia pistons. The 302 head was milled .125 for 8.7:1 with a 4 1/8 bore. This was in his 1955 book and he talks about all 4 heads.
I have run everything from 10w30 to Valvoline 60w racing oil in my 270. I never hurt a bearing and I've been driving it hard since 1978.
Last edited by Beater of the Pack; 11/19/13 11:43 PM.
