Speedmaster spark plug holes improvement??

The diamond pistons were 11.4-1 advertised but like I said the block was never cut and I did a fair amount of chamber work. I didn’t really want the open chamber heads but someone hurt one and I got them for 350 dollars. Easy chamber work fix and a couple valves. I ended up going with 2.08 valves anyway. On alcohol I fairly calculate final compression numbers. If anything I’m to low. Lol. This 408 I’m doing for 2021 View attachment 1715682717 View attachment 1715682718 race season is a different story


What pistons are those, looking good.