roger

just curious on a ls1 how much preload do most of you run when using an aftermarket cam.0 lash,1/4 turn,1/2 turn,etc..etc...

just triing to figure out a valve float problem i am having with a sbf engine and i see alot of ls1's turning alot of rev's with not to much spring pressure and pretty agressive cams.

let me know.

roger

TTT....no info?

Hardtop

iTrader: (3)

You torque the rocker bolt to 22 ft.lbs.

Bruce

Gary Z

There seems to be some confusion here. Hydraulic lifter preload is adjusted by changing pushrod length. If we are dealing with solid lifters and adjustable rocker arms then the question is "what is the desired valve lash". Torque is not relevant.

-Gary

<small>[ December 13, 2002, 01:08 PM: Message edited by: Gary Z ]</small>

CW 99 Z

Actualy if you have adjustable rocker arms you use the turn method like roger said. Most people are still running the stock rockers though. On most of the high performance sbc motors Ive built I usually do zero lash then 1/4 turn. On a couple race only motors I've just used zero lash but it sounds like a sewing machine. I'm not sure if this will fix your problem though. Your probly still gonna have to change springs.

Pro Stock John

iTrader: (34)

Stock lifters, stock pushrods, stock rockers... if you tq the rockers to factory spec you get ~.050/060 lifter preload.

If you get an aftermarket camshaft, many times due to the different base circle you end up needing shorter pushrods otherwise lifter preload goes up like crazy... Been there, I am the founder of the .110 preload club circa 1999.

rich

I think the confussion was in that he was tring to get a ford to run like a ls1. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

<small>[ December 13, 2002, 01:47 PM: Message edited by: rich ]</small>

Gary Z

Maybe I am the confused one. Roger is a Ford man seeking LS1 wisdom. CW is implying that it is common practice to use adjustable rocker arms with hydraulic lifters. Is this the case? I don't see why anyone would do that. The stock LS1 rocker arms are very fine despite not having roller tips. Are there adjustable rockers that are lighter than stock?

And in reply to PSJ, yes, it is true that with stock components, lifter preload will be correct when the rocker is properly torqued but preload could be correct with the rocker bolt improperly torqued. That is what I meant by saying torque is not relevant. With non-adjustable rocker arms, hydraulic lifter preload is determined by pushrod length.

Respectfully, Gary

<small>[ December 13, 2002, 01:58 PM: Message edited by: Gary Z ]</small>

Hardtop

iTrader: (3)

The original question was about the preload on a LS1. On a conventional SB I like 1/4 to 1/2 turn after zero lash. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Bruce

Gary Z

Bruce,

The LS1 is not a conventional small block. In particular, the rocker arms are not like SBC rocker arms.

Respectfully, Gary

roger

well to awnser a couple questions this is on a 5.0 engine,the one in my sig.since i have had it running i run into valve float around 6200.this is with a 2.02 and 1.60valve,titanium retainers,adjustable shaft mount rockers and stock size push rods and stock lifters.i have triied two diffrent sets of springs on it

first set
130# seat
340# open

second set
155# seat
385# open

same problem with both sets.the cam is a fairly aggressive piece,base on an extreme comp lobe.i have since ordered a cam from a tuner that does very well with 5.0l cams when used in hight rpm applications.the shift points are 6900.but i had asked him about preload and i have always set mine around a quarter turn but he recommended a full turn,which to me is odd.but i trust his opinion.the cam overall though has a pretty mellow ramp which in turn means alot of duration.

but one thing i am curious about is what is the diffrence with the ls1 engines.all the cam seem to have a real aggressive lobe but they still turn a decent amount of rpm with no valve float.whats the diffrence?

Gary Z

Roger,

I'm not a racing expert and I have innocently gotten in over my head. I thought I could help but I seem to have led your thread astray. I am now interested in your problem and hope I can learn something with you. I have two questions: 1) How do you know that you are experiencing valve float? Valve float can be destructive. If your engine is simply failing to rev beyond some point, the reason could be something other than valve float. It could be fuel or ignition problems. 2) Does your engine have solid or hydraulic lifters? If you are experiencing valve float and you have hydraulic lifters then the problem is probably due to lifter pump-up.

-Gary

<small>[ December 13, 2002, 04:42 PM: Message edited by: Gary Z ]</small>

roger

its a hydraulic roller set up.checked fuel and ignition and there is no shortcoming here.

it maybe pump up but the guy i am getting the new cam from says that it wont happen with his setup.
i am just curious the diffrence in engines and thought i would find out how the preload was set on the ls1 engine.

Gary Z

Roger,

The LS1 has hydraulic roller lifters and non-adjustable rocker arms unlike the adjustable rocker arms of the original SBC. LS1 lifter preload is determined by pushrod length. That's all I know. My LS1 Camaro is bone stock. Your car is faster than mine.

Good luck, Gary

Pro Stock John

iTrader: (34)

Ditto on what Gary said, the rockers sit on a bar as well. Only way we can make little adjustments is to shim the rockers, big adjustments are done with pushrods.

Roger, sounds like your current cam might have some very aggressive ramps, almost to the point where you might need to run even stiffer springs? I have not validated this but I think some of the XE-R stuff is so aggressive it borders on needing solid roller spring rates... Anyone concur or am I making too big a generalization?

cantdrv65

iTrader: (3)

With the aggressive cam and strong springs you should not use stock pushrods. A weak set of pushrods can also cause valve float. Since its easy to do I'd throw in a set of moly pushrods... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Pro Stock John

iTrader: (34)

... which give you factory preload of around .050/.060 FYI.

If you run aftermarket lifters like Comp's you can end up running less preload I run like .020 or less.

BigTex

iTrader: (16)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Pro Stock John:
<strong>If you get an aftermarket camshaft, many times due to the different base circle you end up needing shorter pushrods otherwise lifter preload goes up like crazy...</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">PSJ, help clear that statement up for me.

I thought most aftermarket cams had a smaller base circle throwing off valvetrain geomerty a little. Having a smaller base circle (like the LS6) would require longer pushrods to maintain stock geometry (and preload). Or you could mill the heads a little. Isn't this why the 02 LS6 went with longer valves? I would think if your pushrods were too short that you would have less preload.

CW 99 Z

I guess I should have clarified more on what I was saying. It was already stated in a round about way that LS1's dont have an adjustable valve train and roger does. I just gave him my opinion on adjusting them. But like I said I dont think this is your problem because a lifter usualy wont pump up at 6200 unless youve got way to much preload on it or thier just sh$t lifters. You can try using zero lash and see if that helps. Like someone said, getting stronger pushrods wouldnt be a bad idea if you havent already. (edit) Just reread your post and I really dont think it is your springs. 385# open is a lot of spring pressure for a hydrolic lifter, especialy a stock one. I honestly think you should change to an aftermarket set of lifters. FYI I had a buddy that had a 92 5.0 that he turned upwards of 7 grand that had a comp cam (not sure which) He also had crane lifters, springs and pushrods.

<small>[ December 14, 2002, 01:11 PM: Message edited by: CW 99 Z ]</small>