Hi I am just finishing rebuilding my wilf green 300 and wondered if the piston/head clearance is the same as the 250. Checked clearance with original head gasket and it’s to big. Can’t find any info in manuals. Any help great full. Cheers mike
Piston Head clearance for the 300 is the same as a 250.
In my experience with 3 Wilf Green 300s all had wide squish bands 1.75 to 3mm,
larger the clearance the lower down the rev range the engine pulled from, but less top end, 3mm 65mph.
I had them machined down to 1mm clearance and the engine had the same power characteristic’s as a 250 but with more GO!!