Post Wed Nov 25, 2009 4:57 pm

Rocker geometry

I'm sorry to say that my recent comments have caused more anxiety and e-mails than I anticipated.
If you have a stock knuck engine with minimal wear and nearly stock lift (duration doesn't matte) you need not do anything - the original geo is excellent. If you have a pan or shovel, they can be improved to better than new, but it's not fun and I don't know of anyone who offers this as a service (perhaps Baisley, but only as a complete rebuild).
I'm sure there are shops that (more or less) understand this stuff, but very few want to pay for it, and are simply confused when they find out how complex it is - and run away to get a comforting and inexpensive answer ("my friend Bubba did it this way, and it's been running for 2 weeks and hasn't blown up").
If you aren't sure what you have, it's going to take a lot of work, beginning with all the changes if known, and the dimensions if not (lobe height, stroker plate, which tappet block, oversize valve).
If your trig isn't good, don't try this at home.
DO NOT ask this question all over the net in hopes of getting a simple and easy answer ("just use lash caps", "shorter valves", "adjustable pushrods"). I have yet to see an answer that is even remotely helpful - the best ones say nothing specific and caution "it must be optimized".
The famous "how to use Evo parts on your shovel" posts are a mine-field of complete nonsense.

If anyone has a very limited and narrow question, e-mail me and I'll give it a shot.