valve setting SS

[nhradave]

Thanks for the input guys. This Super Stock stuff is tough, I have bracket raced forever but this is a real brain pain.
My first NHRA event is New England Dragway July, 20 and we are trying to get the set up. The folks at the track have been great, we go for chassis certification on Friday of the event.

Dave Garland
#1000
SS/HA

[Alex Denysenko]

in my ss 289 i have found power on the dyno and et at the track by ruuning the lash as much as .015 looser than spec we've been doing it for years we use only ultra premium lifters and push rods as well as springs retainers etc as this practice can be hard on parts

[nhradave]

Does it free up the revolution of the motor or componsate for bad air?

[Ian Hill]

i know its not a super stock, and i might be ridiculed abit for this response but here goes. In my 350 crate motor camaro i do not run the required .015" squish spaced out lhydraulic lifters, i run solid lifters (gasp! I can here the phone lines buzzing already...) i have tried many different combinations of valve setting gaps, now i run near to zero lash. it may be because we are limited to the amount of lift our cam shafts are allowed to be it maybe because many things my non-engeneering mind will never figure our about cam shaft geometry, but for what ever reason my car runs the quickest when i set my lash to .003" cold, which on my set up closes tighter when hot.
I have heard it all before, this will never work work, your engine should not fire when its hot, you are goning to wear your cam shaft down to nothing. (I also run way too much valve spring pressure as far as most go and have read all the resent posts about spring pressures and lash gaps, but every time i add pressure my car speeds up, so until i have wiped the cam out i continue to tighten it up) and in my mind, the first rules of thumb is simple: what is the life expectancy of your engine, what could you live with for minimum life expectancy ($ wise), are you using the most expensive oil you can afford (because in the racing world of high end oils it sure looks to me like to more valuable the oil the better - within reason), are you changing your fluid often enough? if you say yes to all of these then adjust until you start to slow down its simple. And if you want to know, when on the "rock" of the opposite rocker you should adjust your specific engine valve lash for the rocker you are on, just put a dial indicator on the rocker you are working on and run through an entire sweep of the opposing rocker. this will tell you where your "sweet" spot is to adjust your rocker. do you adjust them as the intake opens, as the exhaust starts to close? the indicator will give you a sweep of crank shaft rotation that is ok to adjust by. once achieved, write it down. then repeat for each engine you own - every engine is slightly different... cam shaft over lap also affects this.

just my penny's worth
Ian

[Ian Hill]

oh ya... and about the zero lash thing. we used to run zero lash cold in our honda engine powered go karts. seemed to work great except we had to cool the engine right down between heats because the engines wouldnt refire hot because the valves were hanging open ofcourse. but when turning a 3600 rpm engine to 6700-7100 rpm this combo worked best. kinda sounds very similar to my crate engine only with an extra $0 added to the end of the value on the invoice!

Ian