I have a502zz in a 30 foot wellcraft,I am on my third engine rebuild.I lowered the compression to around 8.5-1.The engine is .060 over sized.I only got 20 hours on it when I lost compression on #4 cylinder,all three engine jobs failed on #4 cylinder.Can any body tell me what could be wrong?Thank-You Lorne.

When you say engine job failed on #4 what do you mean? Just compression? Bearings/pistons? If just compression maybe you just need a detailed look at the head on that cyl.