I understand that there are many varibles in this, like cam profile, but I set the Terraplane to .019" tonight(from the .021" my sprint car engine builder buddy burned into my brain). Before the lead acid failed on me (in front of the conveniently not home HotRonVon's house), she seemed to run pretty damn nice... Can't seem to find the cam spec sheet (damnit), but I think the lift is around .65" What do you run? Anyone ever dial 'em in too tight? At what clearance? Should I be able to go any tighter without fear of damage? Mike
When I called Isky, they recommended .018" for my Z-25 SBC bumpstick. The lift on this cam is only around .480". Ed
Framedragger, call the manufacturer and get the right specs. They are critical, for both the engine's life, and performance. On some of the older solid cams, you could dial in the torque curve slightly, by changing the valve lash. but these are older cams that sometimes run 0.030 clearances (pretty big). Rollers run tighter clearances, so getting them right is more important. When I ran a solid roller, way back when, they even gave different specs for setting the lash hot, or cold. And add aluminum heads into the equation, and it changes again. All due to heat expansion of the engine changing clearances. In dealing with aluminum rods/high dome pistons, clearances are even more critical. Esp at high RPM's. From what I remember, cold specs were loose, for a roller, like .010 to .012, and tighter when hot, like .006-8. All clearances were tighter than a regular solid cam, though.
My Lunati solid roller card says to run a huge amount of lash (.022 int & .024 exh, HOT!) (it's a .632 lift), but I will be screwing around with the lash while it's on the dyno to see what we can do to the power curve. If you can wait a few weeks, I'll let ya know! BTW: as long as you have ample piston to valve clearance, the only trouble setting the lash too tight is the valves may not seat completely, making it run like shit, if at all; So don't be afraid to try it! (you can alway loosen 'em back up!)
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