Figure my compression

13:1 on 91? Good luck...lol. You need a MUCH larger cam, even at 6K feet. I'mnot a pro with altitude correction although it is in my future..lol. but it seems like onaverage 1/3pt for every 2K feet is in the ball park. So if you are at six, and never go down lower, 13:1 might be ok with a decent cam. But 240° @ .050 I dont think will be enough. Not with iron heads too. I'd be looking in the 260°[email protected] stuff, and keep a close eye on the plugs' ceramic for signs of detonation. Have a caht with a few saavy custom cam grinders. The one you may need probably is not a catalog item. Engle has some nice lobes, and a full custom cam isnt very pricey.