[HWYSTR455]

You can calc the volume by checking how far in the hole the pistons are with a plate and mic with the heads off, knowing what pistons you have (look up volume specs), bore, and actual chamber volume, You have to remove the heads anyway, so just do what you can before you order the heads.

With that info, you can determine which head size you need, either 72 or 87cc, before you order them.

Remember, with aluminum heads, you need about a solid point of SCR more than with iron heads.

I would suggest somewhere in the 10.25-10.5 range if your tuning skills are on the average side. Safer that way, leaves more room for error.


.