Thats my thinking re compression ratio. But when I spoke to a few people about YB engines they all seem to tell me that I cant run 8.5:1-9.0:1 compression ratios due to valve clearances etc. To which I reply well just run fly cut pistons and then I get all confused by the response and reasons for not being able to do it. Looking around this forum it does seem that the vast majority do all seem to run low compression in their builds so I dont want to go against the grain to only learn later why this is common practice. I expect given the motorpsort history of the YB head that the thing is effecient enough that it can handle decent cylinder pressures without pre-ignition.

Its a bit like who do YB engines rebuilt today have so much blow by? I am hoping to run tighter clearances and better rings etc in the hope that the thing isnt the oil burner it currently is.