I have read for hours on this topic and the answers are everywhere, im looking for a quiet valvetrain right now I have .090 preload on new lifters that has been in oil for a couple weeks (if that matters) running a 23x/61x camshaft street/strip vehicle thanks for any help

 

Ended up with .055" on the intake and .065" on the exhaust.

Was told by a credible source that it would be fine, but would not hurt to go with a .025" longer pushrod for added engagement to the lobes.

You are fine at .090" and my research found some were running as much as .110"

GM specification is .050" - .070".

 

School me then on how if the oil in the lifter is the adjustment a .100" preload would be any different to the "engagement" than a .050" preload? It would seem to me to just take away that range of adjustment until the plunger bottomed out.

 

The spec is 0.05 to 0.1 preload

The LS7 lifters have .220 plunger travel. The goal is to get a little higher than the middle of the plunger travel.

I measured my stock ls1 to need 7.35" pushrods to get a preload of 0.1 on the lifters. I had to use a 0.05" shorter pushrod than the stock one when I switched from ls1 to ls7 lifters. The 7.4 would still work because you would still have 0.07" of plunger travel left, although it's a bit on the high end with .15" preload. I opted for the 7.35's and my valve train is super quiet.

You want to have plenty of oil cushion, but you also want good valve control at high RPMs, so just above the middle of the plunger travel is a good spot to shoot for.

Also remember you will probably lose a bit of preload due to thermal expansion of the aluminum block/heads.

The only thing determining engagement force is the oil pressure and spring constant for the lifter cup spring.

 

The LS7 lifter is not a performance part. It's not designed for aftermarket spring pressures that are required to control aftermarket cam lobes. Can it work? For a while. Is it ideal? No.

 

thanks for the input guys

 

I've read block growth (aluminum) of .006"-.010". As far as high RPM control most are talking about the lifter noise at idle and low RPM. You shouldn't even be able to hear anything at WOT over the engine. So that brings up why is high preload quiet and middling preload noisy assuming adequate oil pressure?

 

Correct as far as the growth is concerned, however that is most likely a mathematical calculation based upon variables of thermal expansion. (+- ~.010")

Valve control encompasses many things just as mentioned above. ie: rockers, valve guides, valves, springs, pushrods, cam lobes, and design of such. Add tolerances as well as weights of the listed components; and there are too many variables to accurately state "the" noise is anyhow directly related to lifter preload.

Noise is more of a tribal knowledge. Determining Root cause is the real challenge.

 

I love hearing you say this Jake, as I too tell customers the same thing.

The stock lifters, even a LS7 lifter just isn't designed for aftermarket spring pressures commonly used and associated with even your run of the mill type cam grinds out there today.

 

I know people love their hydraulic setups... but real performance is with solid roller or at least a limited travel hydraulic lifter. You want to take away as much of the lifter action as you can out of the valvetrain. This is especially true once you get into the 6K plus range.

 

what lifters would you run? i'm thinking about pulling them out now after reading this. I have a set of GM performance 88958689 new but they are old, I read where many of those older ones failed. ill list my specs below

iron LQ9
243 stage 3 CNC 2.02 intake all stainless valves
lingenfelter dual springs 160 @1.8 424 @1.125
BTR cam 227/238 613/586 110+3
7.4 push rods/trunion upgraded rockers

 

Morel 5315 are a good lower cost alternative.

 

I am running 5315 models with no issues. #380/150 springs, 53 lobe, slp 1.85 rocker, light weight valves, 5/16 heavy wall p rod. The car pulls to 6800 quick as lightning and wants to spin higher.

If you go heavier valves, higher spring pressures, more aggressive lobes, then I would be looking at a Johnson short travel lifter with a 11/32 or 3/8 dual taper push rod.

Look at the entire valvetrain assembly as a whole and build it that way!!

 

Speaking of which I have Lunati (Morel) 72523 high rpm, limited travel, "race" lifters. According to Lunati they require a fairly light preload but I wonder what the full travel is.

 

Don't know for sure. I know my Johnson short-travel lifters only have like .058" of travel total. So my preload is .035" cold. It'll grow to .030" or more when hot, so I'd be about in the middle of the travel range.

 

Ditto, but I went to .038" preload cold. 2126ST I think was the part