Invest in a uni-Syn to balance the carbs. they turn up used on ebay once in a while and are not that expensive new. You will be happy you did. Makes synching in the carbs an enjoyable experience. My 235 motors all seemed to like, with hotted up cams, something like 3 to 6 degrees advance. Before I had a dial back timing light, I would simply advance the distributor a little at a time until the motor pinged, then backed it off a little.
