I JUST PUT TOGETHER A 427 FOR MY 08 CREW, AND I USED THE COMP SHORT TRAVEL LIFTERS DESCRIBED IN THE HEADER. WHEN I PURCHASED THESE LIFTERS I WAS TOLD (BY COMP) THAT THEY COULD BE SET UP TO BE A QUIET LIFTER, BUT NEEDS .030 PRELOAD. GOT THEM SETUP NOW AND NOW HAVE THEM INSTALLED WITH ABOUT .021-.025 PRELOAD. I GET A GOOD DECENT AMOUNT OF VALVETRAIN NOISE SO I CALLED COMP TODAY AND ANOTHER REP SAYS OOOOH THATS WAY TOO MUCH PRELOAD, YOU ONLY NEED .005 PRELOAD HOT OR CLOSER TO 0 LASH. SAYS THAT RUNNING TOO MUCH PRELOAD COULD MAKE THE PUSHRODS KICK OUT FROM THE ROCKERS, (NEVER HEARD THIS), SO WHAT ARE YOU GUYS RUNNING ON THESE LIFTERS AS FAR AS PRELOAD, AND HOW NOISY OR QUIET ARE THEY IN YOUR APPLICATIONS? MY PROBLEM I AM SEEMING TO BE EXPERIENCING CYLINDER BLEEDING DOWN AS AN EFFECT OF MAYBE A LIFTER KEEPING THE VALVE OPEN JUST A BIT, BUT IT SEEMS TO GO AWAY AFTER 1800 RPM's and OR RIGHT AFTER STARTUP, THIS PROBLEM IS NOT EVIDENT, UNTIL OIL PRESSURE RISES, SO THERE MAY BE SOME PROOF IN WHAT THE LAST GUY SAYS ON THE 0 - .005 LASH.
WHY IS IT EVERYONE IS NOT REQUIRED TO KNOW THERE PRODUCT IN COMPS TECH SERVICE DEPT. THIS WILL LIKELY IF NOTHING ELSE CAUSE ME A NEW SET OF PUSH RODS.

WILL TAKE ANY HELP, AND OR SUGGESTIOINS AVAILABLE!

 

The guy at comp thought you were talking about solid lifters. Lash is only used with solids.

Did you check the footprint on the tip of the valve stem? Are you running regular or adjustable rockers?

 

i am running regular yella terra rockers, no adjuster nuts. Both guys knew we were dealing with hydraulic lifters for sure, both were speaking of preload when they were describing the figure to shoot for. I think i am gonna try the set i used in the cammed
l92, as they were 7.375 length.

 

No one else using these short travel lifters? What are your expeeriences and finding please.
Thanks

 

Most guys around here use GM LS7 lifters. Good luck with those Comps, hope that they stay together for you...seems like most Comp stuff (besides their cams), ends up in pieces or causing a catostrophic failure.

 

Those are actually an awesome set of lifters for high RPM use! They only have .050" travel in the entire body of the lifter. If you in the .020-.030" range your perfect, leave them the way they are. They absolutely help out valvtrain stability! The guy who said .005" heard "short travel" and was thinking about Comp 875-16s. He was incorrect......

I would recheck your preload, with only a .050" window its easy to miss. Are these in your Denali?

The lobe on the cam is what will make the sound difference. Its about how the exhaust lobes seat the valves. Comp just came out with some lobes (LXL) specifically designed to help out our engines with valvtrain noise, since they have ALWAYS been loud when adding aftermarket cams/intakes. Your such a negative Nelly, I use Comp parts in everything I build and havent ever had a problem. It does help that I understand what Im doing and have experence with a touch more than most, but it is FAR from rocket science.

 

THanks for the helpful insight. Yes these lifters are in the new 427 engine I have installed in the Denali truck now. I tried just for kicks taking the rockers and shimming them to as close as I could ge to "0 lash no preload" and the engine runs and idles MUCH cleaner now, but it actually sounds like a solid roller, as I took feeler guages to check and I am about .005-.008 lash right now, so the extra noise is actually explained right now. The noise from the valvetrain was not much of the concern as the performance and the feeling of a cylinder loosing cylinder pressure (missing feeling), i.e. especially when I was cruising around in 5th or 6th gear at low rpm or any gear under 1800 or any off idle tip in acceleration. The cam is not very big in my opinion for the size of the engine so I dont think it is the cam chopping at low RPM causing this feeling, but maybe I am wrong. The cam I am running is a Lunati Voodoo series cam #60514 ground on a 111LSA. 277/283 227/233 .584/.584 with 1.85 yella terras so lift is about .635/.635 on a 111LSA +4 advance. I am attempting to use the method of 1/4 turn to justify a range of actual preload as described by some members on tech, anyone have a better method for a nonadjustable valvetrain?
On another note; Everything is seeming to have worked out pefect on this build except this little valvetrain issue. Truck makes great power, and no other noises after these NOISY Forged probe pistons get up to temperature. Should I have maybe opted for a coating or something, I have built many iron block engines, but maybe this aluminum engine increases the sound a bit, the first startup I thought I swapped in a deisel lol. It doesnt seem to be as back on a warmer day and it was COLD here on the first startup. Once they are up to operating temp and no sooner then they quiet down pretty nice then.
THanks for everyones help, in this matter
Kenneth

 

For SweetS10V8 or anyone who knows:

WHat is the actual difference in the 875-16 and my 15850 lifters. on some of the specs on the 875-16 I have seen it said that .005 max preload, but it doesnot say that for my 15850s. But both are labeled as a short travel Race lifters. Are the 875-16 just a shorter travel?

 

Kenneth,

I would not run it that way for long at all if at all. The rocker geometry needs to be set up so that the tip of the rocker leaves a nice foot print in the middle of the valve tip throughout it's travel. This helps with rocker arm, valve, and valve guide wear. The way to change the foot print is to lower or raise the rocker arm. If you do not have adjustable rockers, then it would stay all the way torqued down unless you shimmed for a proper foot print. Then you need to pruchase a pushrod for the desired preload. I am not sure if you have done this or not before, it is fairly easy.

Clean the tip of the valve stem, and cover it with a magic marker. Install the rocker and pushrod. Tighten it down to the proper torque. Turn the engine over one revolution, or cycle of the valve, and look at the line left on the top of the valve tip. If it is not in the center, you can then shim it. If you shim it up, the line will move towards the center of the engine. If that line is not in the right spot, that could be your noise problem right there.

 

You made mention of this in an earlier post and I failed to mention that I did check that when I changed the shims. I had a just about perfectly centered pattern on the tip with the shim that yella terra sent with the rockers. So I realize I lost focus in this valtrain mess as I can't use the shims to get the correct preload, guess I am gonna have to find a dial caliper long enough to measure the length of my adjustable pushrods accurately, and just order a set of pushrods .250 -.030 longer than the zero lash.
Thanks man, I was trying to over simplify this non adjustable valtrain thing with shims, but you are right this will not work.