I've built several circle dirt track engines with 400 blocks and early short stroke cranks-one of the most successable combo was 400 block with bearing spacers and late 302 cranks( early smallest diameter were very difficult to access) 4.155 bore with 3.0 stroke--------

also used lots of squirters to cool bottom of pistons--

a mistake in this thread early on about valve clearance--------post #2----.008 and .0012 ( should be .008 and .012)