hi all

id just like to know how do you calculate how much needs to be shaved off a head to reduce the CC and in turn increasing CR.

ive CC'd everything, the pistons are 14cc, head gasket 3cc (.6mm GX) and head 26cc. that gives me a CR of about 8.65:1, im chasing about 9 or 9.5:1.

engine details are A15 with new standard offset dished pistons and rebuilt bottom end, wade 140 cam, twin side draught webbers, double valve springs. head will have 37IN and 33EX valves, all ported and matched.

changing pistons to flat top isn't an option, i didn't want to go down that path. im only left with shaving the head.

so should i be aiming for 9 or 9.5 with this setup? so i need to reduce the setup by about 3cc, is that alot to come of the head?

thanks