This just came up on the cam overlap thread(over on LS1TECH). Didn't want to thread jack. So, what is this and how does it change overlap?

P.S Sorry if this isn't Adv. Tech material. The subject came up in the Adv. Tech section of LS1TECH. Just figured I'd get a more in depth answer here. Thanks.

 

Has nothing to do with overlap, that's defined by the cam.

http://shbox.com/1/4th_gen_tech2.html#adjust_valves

 

unless you have overtightened the rockers in a hydraulic lifter setup, in which case your valves will stay open longer... possibly forever, but it's anybody's guess for how long...

do the same thing in a solid lifter and they just never close

 

I know shoebox and GM recommend 1/4-1/2 turn past zero, but I was told by a very reputable source that the most power is made the closer to zero that you can run. I'm going to do mine 1/16 of a turn past zero.

 

on a hyd. lifter you want it preloaded you do not want it too loose.

I have tested several ways to run my lash and the car makes better power with a tight hyd. set-up when I ran a 1/4 turn I feel like I lost some m.p.h from that with a tighter adjustment I picked it back up

 

On a solid it will change all of the specs a little. the running duration at .050 is a little shorter than advertised because most spec the cams at zero lash but cutting .014-.026 off of a lobe will change the specs. I don't have enough experience with solid cam spec and formulas to give you any #'s though maybe someone else will chime in.