i was talking to a head remanufacturer about vortec heads for my 89 lo3. it currently has 187 castings.

i told him my concern was how much to mill the vortecs to get from their 64ccs to the stock lo3 58cc chamber size.

he insisted that pre-87 305 heads were 58ccs, but 87 and newer 305 081 and 187 castings were 64ccs.

i'm sure everything i've read on this has all lo3 heads at 58ccs.

help?

 

youre right, 87+ 305 "187" and "081" cylinder heads are 58cc.

 

The only two combustion chamber sizes that I've ever heard of coming on a 305 were 58cc and some early 305 heads had 60cc. 64cc is a standard 350 chamber size.