JD, your max rpm depends on how long you want the engine to last and what you have done to improve it. Continuous running of a stock 235 over 3,000 rpm is not recommended. I've had mine (with a 3/4 race cam) up to about 4,500, but only for a very brief period. If you have balanced rods & crank, electronic ignition, the right pistons and valve springs and a better damper, 6,000 is obtainable, but not recommended.
