gomer

iTrader: (13)

I'm looking around for springs to install on my LS6 style patriot performance heads that I'll be getting next week. I have been reading around alot about springs. All of these pressure numbers make sense to me, but make me wonder.. at what point does the factory hydraulic roller lifter "collapse" due to the spring pressure being too high? Has anyone checked into this? I don't want to go with springs that will kill my lifters right after I install my new heads and my larger cam.
Thanks

Tin Indian

Sample OEM Valve Lifter failure occured @ 153.89 lb/sq in" valve assy. seat press. @ 115 degrees C. oil wetted (with default emissivity of 0.95) recorded with a continual spring cycle rate of 835 cycles/min during the climax of a 400 hr. 'Spintron' exercise.
Cal. per Mil Spec: MIL-Assy-142786-1B

Visceral

iTrader: (1)

thats kinda funny...because I was going to say 150 lbs on the seat or so

chris

Visceral

iTrader: (1)

Oh...Also about 140 lbs seat pressure if you have 1.8 ratio rockers.

Tin Indian

Hey gomer ... Ol' Bud'

Just bullshitting you a little

2001CamaroGuy

iTrader: (6)

Lou at LG told me today that:

"Comp 987s are the MAX (almost too much) spring you want to run on stock lifters. Anything above that (ex: Comp 977) WILL need a high performance (ex: Comp R) lifter."

987s have a 130lb closed seat pressure and a 325 open pressure.

soundengineer

iTrader: (16)

if thats the case then a whole lot of people are gonna need new lifters soon.....

Its gotta be higher than that???

and it partially depends on the cam too...how much lift...how big is it???

SStrokerAce

iTrader: (2)

It all has to do with seated pressure, spring rate and rocker arm.

I would say that the 987 is the max on stock stuff.

The rocker arm ratio not only multiplies the lift but it multiples the spring pressure back on the lifters. So a 1.8 will stress the lifter more than a 1.7 will on the same spring.

I'm suprised that the stock lifters hold up to 130 on the seat with the 1.7 rockers we have on the stock LS1 motors.

Bret

v8maro

iTrader: (4)

so with comp 978's, stock lifters and a cam that does .595 lift, would that kill em?
BTW, what happenes when you colapse a lifter? I know the motor needs to be opened to put new ones in but, does anything physically break when they colapse?
-Steve

Dave Carney

Yeah, me for one.... I've got 130 to 145 on the seat and 321-349 open..... .580 lift .......

2001CamaroGuy

iTrader: (6)

I'm running a TR224/224 0.563/0.563 112LAS cam and Comp 987s with my factory lifters. They seem to work fine but that is the MOST I will ask out of them. When I upgrade to something larger, I WILL be swaping.

Visceral

iTrader: (1)

I wasnt kidding. 150 with 1.7s and 140 wiht 1.8s will tend to bleed down one or more of the lifters resulting in alot of individual lifter noise.

Ive done alot of testing with too-stiff K-motion spring.

chris

Visceral

iTrader: (1)

140 with 1.7s probably will not bleed them down, and you can vary the oil weight anyways if you are living in some Death-Valley hot climate.

The result of too much seat pressure is individual valvetrain noise goes way up ("why is there a rocker on this side making all this noise today?""well that noise went away, but now theres a different one making noise. what the hell?") Also the car doesnt make as much power as it should.

I dont think being near the edge (987s or similar) is a bad place to be. Almost ideal in fact.

Chris

Tally TransAm

iTrader: (17)

if 987's are the max to go

how do 978's compare

are they more or less stiff than the 987's

v8maro

iTrader: (4)

Well, if you have PP s2 5.3L heads, the springs are installed at 1.850"'s, so it'd be around 125lbs with 978's and they would be able to handle .600" of lift at that installed height
-Steve

gomer

iTrader: (13)

Thanks for all the input guys.. this is about what I was expecting for answers.

Now, if I upgrade to the Comp R lifters... how much better and stronger are they? Has anyone collapsed one of them?

1dirtyZ

iTrader: (1)

how about 987's with 1.8 rockers and about .600 lift??

what will this do to a motor on the dyno?