I picked up a lightly used (150miles) 427 that was in a 69 yenko clone. It has a solid lifter cam and the top end is noisy. Through the guy i got the motor from, I was able to get from the engine builder only that it was the correct cam for a yenko 427, but he doesn't remember which cam. Is there a safe backlash setting i can use on the valves without knowing which exact cam i have. The motor was set up to run on pump gas 10:1 comp. It seems that .024 or .025 is common backlash. Any thoughts?