[Chevy454]

I think you may find that your engine will like a little more total timing. We have had the best luck with our big blocks at around 39, and I think I remember hearing COPOpete say that his L-72s are right around 39 as well. I would like to hear what everyone else is running, though. The timing needs to be in as fast as possible, like around 2,500 rpms. That seems to be where most big block owners like it.

A quick question for you: are you running true aviation fuel, or just high octane racing fuel? If you ARE running the AV fuel, be careful...lots of ethanol in that stuff, and it's very hard on anything rubber (carb internals for example).

How do your plugs look after running the car? If you are planning on racing it, then you need to install fresh plugs, run a hard pass, then kill the engine as soon as possible, and check 'em. That will give you your best reading. Your power valve sounds a little low, but everything else sounds close. Not sure what the factory valve lash is for aluminum heads, though...for iron, I think it's 24/28. Any "L-89 gurus" here with the lash specs?

Pete (or anyone else!): jump in here and help us out!