anybody know what the compression ratio will be if I bolt on vortec(L31) heads to my 83 305? Does it depend on Piston spec.? What is the stock rocker ratio for the vortec and will it work on my 305 without interference with the pistons? Only have 89 octane gas on this island so will that put me in the 9.5:1 area? Thinkin of using a 600cfm carb on a edelbrock rpm air gap. Any suggestions on slugs and cam for my build up? Will these mods get me into the 13's?

Thanks

 

Flat-tops with standard valve reliefs in a 305, you'll have about 8.5:1 or less CR. Shave the heads by about .040" to get the chambers back down to 58cc and you'll have about 9.5:1 with those same pistons. On a 350 w/o shaving, about 9.5:1.

I'm running 9.5:1 on regular pump gas. But, I've got computer controls and knock sensor. My 396 with 9.7:1 requires the best pump gas - but that's a big block with closed chamber heads (a whole 'nuther story).

 

5, can I change the pistons without shaving the heads to get 9.5:1 compression? If so what kind?

 

Shaving the heads would be a whole lot cheaper