valve setting SS

[nhradave]

After great debate on valve setting with fellow racers, this is the conclusion. Super Stock SB Chev.
When the intake opens and is half way to close, set the exhaust. When the exhaust starts to open (50%) set the intake.
This appears to be the best way????
If the valves are set at 22 thou. I am told the 30 thou. is faster but harder on parts (does this not remove lift from the cam)?

[randy wilson]

Yes, it removes lift from the cam And, all cams are different. Some react well from card settings, some like a little looser, some tighter. I had one 292 that loved the intake .05 tighter, to the tune of a tenth. Not kidding, but does not help all engines, or cams. Just try different settings and see. Hope this helps.

[1320racer]

EO/IC...when the exhaust valve just starts to open, you adjust the intake valve lash on that cylinder. When the intake valve has fully opened and is almost closed, you adjust the exhaust lash on that cylinder and you check your settings using the go/no-go method. If your setting .020 lash then .019 goes and .021 no goes.

As for lash adjustments outside of spec...you can safely go .008 either side of spec. Lash loops...opening/closing lash is worth power/ET. Looser maybe be harder on the valvetrain depending on the cam profile.

http://www.harveycrane.com/lashloop.htm

[buzzinhalfdozen]

The very best way to set your valves is to turn the engine using a rachet by hand... turn it in very small increments near the Exh. opening measuring the lash as you move the engine. You will see a point where you measure the MAX. lash, remember this point (maybe jot down the degree off the balancer and what the lash is) when you move it further in the rotation your lash will decrease. The point at which you measure your MAX lash is where you want to check it, as stated earlier some cam profiles are unique and require a different approach. When you have the Int. point of movement figured out, simply use the same method on the Exh. of course at the point the valve has pasted max lift and is closing. I've spent a fair amount of time trying to show my son how to properly (at least in my mind) set valves...he's starting to get the idea of the importance of selecting the proper time to check the lash.

[Mike Pearson]

Depending on your cam selection and rocker arm arrangement your car will probably want a looser valve setting. Mine likes .035 on the intake and .028 on the exhaust. You need to run a good high pressure lubricated lifter to make them live. The lifters are the weak link. I check mine every race and if anything is loose the lifters need to be checked. Use a good quality oil and let the engine run at idle for a while before you rev it up. this proceedure has helped with extending my lifter life. Weak valve springs will kill your lifters as well.

[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