Hi,

I've got two 81SM6090 cross-hatch heads from an '82 and an '85 CVH.

Both heads are 1.3 casting (same intake valve dia, but smaller exhaust valve dia [1.3: 34mm/1.6: 37mm] than the 1.6 casting as stock)

According to pumaracing.co.uk, the cross-hatch heads are the best CVH ones for valve size upgrade and porting (due to thicker walls).

Do you reckon that despite being 1.3, a +2mm intake valve (from 42mm) upgrade can be done on these castings?



cheers