Joe B

I noticed something just recently that I felt was worth posting........Since doing the LE2 package a bit over a year ago(which has been running real good), I've been messing around with trying different amounts of hydraulic lifter preload (on my OEM lifters) to yield the best power (dragstrip) results......I always felt like after 5900 rpms(or so) the power would drop off rather abruptly instead of hanging on longer like I felt it should......well after trying about "every" possible lifter preload setting from an excessive 3/4 turn, down to my current Zero preload setting that yielded the best track times(and upper rpm power)......I had to assume that any little bit of lifter preload I used was pumping up at high rpms,therefor not letting the valves close all the way when they should have been, causing the high rpm power to drop off ........so anyway... were starting to get some really hot weather again here in florida, and just lately the power on the top end(over 5900 or so) seems to be dropping off again almost like before......so for the heck of it I decided to try some heavier viscocity oil instead of my regular (since the car was new) Mobil 1 5W-30 Weight synthetic oil....instead I put in some Mobil 1 15W-50 weight synthetic oil......I made no other changes and took the car out for a drive....I got the oil temp up to about 200 degrees....and then did some full quarter mile passes and then some second gear blasts shifting manualy to see exactly were it was pulling to.... and unbelievably for the first time "EVER" the car pulls VERY hard till 6700-6800 RPM's without really any abrupt drop off like before, but more of a regular waneing "after" the ideal power peak (all confirmed on my pro-comp memory tach)....honestly the power above 6000 RPMs feels like night and day compared to just before the oil change ....so im now forced to believe that the OEM lifters were "also" compressing some at the upper RPMs causing the power to drop off....damn hydraulic lifters....anyway, I think my next cam from Bret will be a solid type(like I've "always" ran on "all" my past cars) just so none of these crappy high RPM hydraulic lifter issues can even exist....Just figured I'd post to let you guys know what I found ..............Joe

seawolf06

You think this pumping up could be fixed by getting some oem style aftermarket lifters or even the racing LS7 lifters everyone's been raving about?

Joe B

Im not sure if a set of OEM aftermarket replacement lifters like the OEM type Crane's or the OEM type Comp's would be any less likely to pump up their preload (or compress down) without trying them, but personally I can't really see any improvement in their design over the factory lifters that would help them to not pump up or compress...but who really knows for sure without trying them, ya know..............all I know is that some of the hydraulic lifters out there like you mentioned IE: LS7, New Cadillac Lifters, Morell , Ect..... "seem" to be coaping with higher RPM's and increased spring pressures without people openly complaining about them, but many people woudn't know for sure even if it was happening anyway(slightly or drasticly) LOL....But I think Instead of dealing with any more (always heavy in comparison) hydraulic roller stuff, I'll most likely just go back to running solid stuff........IMO, and experiences, solid cams and lifters actually hold their lash settings "REAL" good, and don't have to be re-adjusted very much at all (contrary to what many say), and atleast ya NEVER have to worry about the slightest bit of lifter pump up, or plunger compression at any RPM level......I guess I just don't trust the hydraulic stuff to work flawlessly like the solid stuff always has for me......even at this point...with running zero lash(so that there's nothing to pump up in the lifter), and now running heavier oil that drasticaly helped the lifters plunger from being excessivly compressed at high RPM....who really knows if there's still possibly some more power being thrown away from some lifter plunger movement that "may" still be occuring to some degree.....really, just no way to tell for sure.....guess I could try some 80 weight oil and see if it pulls harder up top again HaHa............Joe

Z-RATED94

Thanks for sharing this info with us. I'll have to give it a try and see what happens. I wonder if the royal purple oil I had put in when the shop put the beehives on helped a little with the improved rpm gain the car experienced? I don't know the weight they used, but will ask them.

tireburnin

On a somewhat related note, what differences did adjusting the lash have on track times? You found the best performance at zero lash with new/stock lifters? I was always under the impression they liked 1/2 turn lash?

Joe B

No problem .......Yea, let us know what you find...........Joe

Joe B

Since I diddn't make ALL the incremental (lifter preload) adjustments at the track on the "same" exact day, the data wouldn't mean very much, but.....I can say for "certain" that there was a marked improvement in upper RPM power pretty much every time I went in and set the valves with less and less lifter preload...........as far as you hearing the lifters liking 1/2 turn preload.....it's actually VERY common for people who are spinning their engines to higher than factory RPM's to find that somewhere in the neighborhood of 1/4, 1/8, 1/16, and even true Zero lash like Im running can yield the best power.....but it's all trial and error

James Montigny

Interesting ...

cnorton

Joe's results are consistent with what I've experienced while building and tuning NHRA Stock LT1 cars. We always set the lash at zero on stock lift camshafts and regularly turn the motors to 7400 rpm with stock rockers and lifter bodies. I do modify the internals of the lifters and bump the spring pressures in order to keep things together. Polylocks on the rocker studs are recommended. Some people would probably be bothered by a little clatter in the valve train but with open headers it isn't much of a problem.

Gripenfelter

I found something similar. I used to use 5W30 oil and switched to 10W30 oil in hotter weather. My engine builder recommended 10W40 so I made the switch and noticed smoother revs up to the redline. This is with dino oil.

I'm switching to Mobil 1 next oil change.

Z-RATED94

I'd like to add also, that I thought the oil pressure was a little better with the Royal Purple.

Javier97Z28

1/4 lash with Mobile 1 10W30 is what I've run my times with, and what I'm sticking with... pulling to 6800 RPM.