427 Camshaft valve adjustment questions

[fasterweride]

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?

[BlackoutSteve]

Set it to about 0.016" cold, get it warmed up and 0.020 - 0.024" will be fine. A little tight is better than a little loose.
Keep your eye on the lash too. If it continues to open, you have a lifter/s and/or lobe/s going bad. Cut open your oil filter and have a look with a magnet.
Another cause for opening lash can be the OE rocker lock nuts. They don't lock so good after they've been on & off a few times. Get a good set of posi-locks.