compression question

[ttop88]

Could someone tell me how much compression would be gained by decking a set of gt40s .040.
Thanks
Mike

 

[91 HATCH]

you will need to measure the cc`s of the head chamber to calculate your compression ratio.i would ask a good machine shop about it.my guess would be that you will remove about 6 cc`s from the chambers which would raise it about 1 compression point as in from 9.5:1 to 10.5:1 but it is just my guess