LS7 lifter / pushrod question

[schufflerbot]

ok, so...

new set of LS7 lifters went in yesterday and she feels a LOT better. however, the noises i was hearing are still there (clacking noise when oil is hot) and its making me nervous as hell. ive read that to achieve the proper preload, i might need to drop down from a 7.40 length pushrod, to a 7.35 if i want the proper preload on em.

my question is, since ive already run the motor with the 7.40s in there, is changing to 7.35s gonna do anything? like, does the lifter set itself to a certain depth from the get-go, or can i change the pushrods out after ~400 miles and be ok with the preload?


thanks!

[camarochevy1970]

you can change the push rods out, just let the lifters sit without the push rods in them for a few minutes so they return to their non loaded position. However, I doubt that will fix your sound. Do you have a video of it?

[schufflerbot]

you can change the push rods out, just let the lifters sit without the push rods in them for a few minutes so they return to their non loaded position. However, I doubt that will fix your sound. Do you have a video of it?

no, but i need to set up a camera and get it on film... thought about that on the way to work this morning.

it happens when the oil gets hot... its a distinct CLACK noise, not an exhaust leak... after that, it tends to smooth out to the 'sewing machine' noise lots of LS7 lifter owners talk about.

[camarochevy1970]

I would think a shorter pushrod would make more noise. But I suppose if you are putting too much preload on the lifters, they may not be building up correctly.

Did you check how much preload you have?

[schufflerbot]

I would think a shorter pushrod would make more noise. But I suppose if you are putting too much preload on the lifters, they may not be building up correctly.

Did you check how much preload you have?

not yet, i just ordered a PR length checker, not really sure how to use it to determine preload, though LOL

im looking for a write up on how to do that, can you link me to something? im coming up with nada

[camarochevy1970]

The way I have always done it, is get the valve you are working with on the base circle. Basically the spot where the valve spring isn't compressed at all. then loosen the rocker and you should be able to spin the push rod. Then tighten the lifter until the push rod doesn't turn any more, and then count how many rotations it takes to get to your torque spec

I believe you want between 3/4 and 1 full turn for proper preload

[camarochevy1970]

also, if you are using an adjustable pushrod, you may want to pick up some checker springs, as you will probably put load on the lifter with the normal springs still in, and you may get an inaccurate reading

[schufflerbot]

so, the checker springs... do i need to remove the lifter to use those?

im confused LOL

you said 'tighten the lifter' - did you mean tighten the rocker?

[camarochevy1970]

yeah, I meant tighten the rocker, LOL

And the checker springs go on in place of your normal valve springs. They just compress very easy things such as this

[camarochevy1970]

lol, so you no longer a member of another site?

[schufflerbot]

well, my profile is still there but all my posting, PM ing and other privelages are gone.

[dantheman]

well, my profile is still there but all my posting, PM ing and other privelages are gone.
haha what did you do?

[camarochevy1970]

haha what did you do?

he went up against "the man"

[schufflerbot]

lol

yah, pretty much.


fukem.

[E.T.M.C.]

that cam with those heads is always a 7.4 pushrod. the comp cam has a smaller base circle and you have to use the longer pushrod to make up for it. most all LS base motors have a slight lifter/valve noise after a cam.(not like yours WAS with the flat lifter) if it is still that loud you have a issue, if it is normal valve train noise then you dont need to worry about it....send me a vid of the noise......

[camarochevy1970]

I thought the LS7 lifters plunger was a little higher thus meaning a shorter push rod should be used?

[schufflerbot]

that cam with those heads is always a 7.4 pushrod. the comp cam has a smaller base circle and you have to use the longer pushrod to make up for it. most all LS base motors have a slight lifter/valve noise after a cam.(not like yours WAS with the flat lifter) if it is still that loud you have a issue, if it is normal valve train noise then you dont need to worry about it....send me a vid of the noise......

I thought the LS7 lifters plunger was a little higher thus meaning a shorter push rod should be used?

yah, thats where im getting hung up... i know the base is smaller, but the lifter cup is taller, so i would need shorter rods, right?

man, this **** is driving me insane lol

here's the difference between the two:

http://www.ls1tech.com/forums/attachments/generation-iii-internal-engine/183512d1244755163-pushrods-ls7-lifter-question-ls7-20lifter-20comparison.jpg

[camarochevy1970]

What do you mean the base circle is smaller? Aren't you running a TSP Torq 2? Isn't that a Crane cams grind? I thought that had the same base circle size

[camarochevy1970]

Did you check preload yet?

[schufflerbot]

no, i havent checked it yet.

i ordered a set of 7.35's yesterday, in retrospect it was pretty stupid, as i dont know if i need longer or shorter rods... but im pretty sure i need shorter ones.

i can feel what HAS to be valve float... you can feel a slight hesitation when the ticking is loudest, you can hear it in the exhaust as well... it has a little 'miss' to it, like a valve is either not opening or not closing... i dont know why, but it feels like its not closing to me.

if the PR checker gets here first, i'll check it out... if the PRs get here first, i'll throw those in and see what happens.

im ready to sell this ****ing car.

[Kingsize]

For what it's worth Schuff I am using a 7.350 pushrod with my LS7 lifters using a stock GM MLS LS2 gasket and I have absolutely zero noise. I had stock rockers and now I have YT and it is still the same, no valvetrain noise at all. I didn't like the 7.400 pushrod as it seemed to have too much preload on the lifter for my taste.

[Kingsize]

I have also had issues in the past with another vehicle where there were resonance issues between different parts that caused a really strange clacking sound. I bought different spring (the same manufacturer as the cam and push rods) and the issue resolved itself. It could be a bunch of mismatched parts not getting along.

[schufflerbot]

well, its all stuff from the ETMC cam install, PRC springs and TSP everything else, as far as i know.

im putting my faith in the PR issue, so wish me luck lol

thanks for the encouragement... it are needed.

[schufflerbot]

For what it's worth Schuff I am using a 7.350 pushrod with my LS7 lifters using a stock GM MLS LS2 gasket and I have absolutely zero noise. I had stock rockers and now I have YT and it is still the same, no valvetrain noise at all. I didn't like the 7.400 pushrod as it seemed to have too much preload on the lifter for my taste.

did you have the 7.4s in before the 7.35s?

if so, was it noisy?

[Kingsize]

Yep & Yep :D

[Kingsize]

By the way where is "The Dirty Dirty" :wtf:


Should I bring "Dolla Bills Yall" :wall:

[schufflerbot]

ok, good.

well, not good.. but reassuring, LOL

everything in my head and what ive researched tells me the PR length is wrong. i need to get my oil pressure gauge put in so i can rule that out, too.

thanks, man.

[Konnie the Goat]

checking the pre-load/rod length is easy.

Let the lifters come up as said earlier (15 minutes tops). Put the checker rod in, put the rocker on. run up the checker just till its snug. remove and measure with 12" dial caliper. add desired pre-load (.045 max IMO, run as little as you like, but I like at least .015') to measured checker. Order rods. You will have to round, as .025" is the usual increment.

FWIW, too much preload is as bad as not enough, maybe worse. Run the lifter cup in the bottom half of its bore, it may never come up. If it does come up, your gross lift will increase, causing PtV clearance issues. Preload can also affect idle quality via manifold vacuum. On an adjustable valve train, you can (and really should if you want it perfect) set preload with a vacuum gauge.

[schufflerbot]

checking the pre-load/rod length is easy.

Let the lifters come up as said earlier (15 minutes tops). Put the checker rod in, put the rocker on. run up the checker just till its snug. remove and measure with 12" dial caliper. add desired pre-load (.045 max IMO, run as little as you like, but I like at least .015') to measured checker. Order rods. You will have to round, as .025" is the usual increment.

FWIW, too much preload is as bad as not enough, maybe worse. Run the lifter cup in the bottom half of its bore, it may never come up. If it does come up, your gross lift will increase, causing PtV clearance issues. Preload can also affect idle quality via manifold vacuum. On an adjustable valve train, you can (and really should if you want it perfect) set preload with a vacuum gauge.

so, since i have the 7.4s in there now... is there a chance ive permenantly ruined the new LS7 lifters that are in there, or do you mean that the lifter cup wont come back up from a lower bore excursion right then?

this makes sense, my idle has been horrible lately too.

*le sigh* this is the wrong way to learn how to work on LS engines LOL

[Konnie the Goat]

There is a chance, but its a very slim one, given the mileage.

I would expect them to be ok still. If one has jammed, you'll know when installing the shorter rods. It just wont be right.

when I say 'wont come up' i mean not only when sitting unloaded, but also when running. Having them down too far makes them bleed down faster, and they are slower to recover as well. This goes for any hydraulic lash adjuster on any engine. Oil is going to follow the path of least resistance, like anything else.

[Kingsize]

checking the pre-load/rod length is easy.

Let the lifters come up as said earlier (15 minutes tops). Put the checker rod in, put the rocker on. run up the checker just till its snug. remove and measure with 12" dial caliper. add desired pre-load (.045 max IMO, run as little as you like, but I like at least .015') to measured checker. Order rods. You will have to round, as .025" is the usual increment.

FWIW, too much preload is as bad as not enough, maybe worse. Run the lifter cup in the bottom half of its bore, it may never come up. If it does come up, your gross lift will increase, causing PtV clearance issues. Preload can also affect idle quality via manifold vacuum. On an adjustable valve train, you can (and really should if you want it perfect) set preload with a vacuum gauge.

I agree but setting pre-load is difficult with a vacuum gauge without a metric **** ton of shims and/or different length pushrods. Not to mention the time it takes to get right. And, yes too much pre-load is bad and often overlooked. If the pre-load is found to be in the middle of two available sizes I always error to the shorter side and/or use the longer but use shims or valve caps if the part is not avaliable or is extremely expensive. Just verify that the pre-load is close to desired lifter bore depth using your checker and the sweep accross the valve stem once rotated is as centered as possible without being excessivly close to the side of any of the valve stems. (yes check them all)

[Kingsize]

I highly doubt your lifters are jacked up. It is probable but highly unlikely. The OEM manufacturers build in tons of tolerance in factory engines, I think you will be fine.

[Konnie the Goat]

I agree but setting pre-load is difficult with a vacuum gauge without a metric **** ton of shims and/or different length pushrods. Not to mention the time it takes to get right. *snip*

Yes, but the LS does not have an adjustable valve train. The parts are available to make it so, but few have bothered with it.

[Kingsize]

Yes, but the LS does not have an adjustable valve train. The parts are available to make it so, but few have bothered with it.

I agree, I wish it were so from GM but, it is what it is. ;)

[Konnie the Goat]

theres advantages to both, but for the most part, i like our 'static' system. If you set it up right, its way easier to get right than an adjustable. If i was going to go adjustable, id want the adjustment at the rod cup of the rocker. Not a fan of the stud adjustment.

[Kingsize]

theres advantages to both, but for the most part, i like our 'static' system. If you set it up right, its way easier to get right than an adjustable. If i was going to go adjustable, id want the adjustment at the rod cup of the rocker. Not a fan of the stud adjustment.

Well the static setup is setup that way for ease of manufacturing. It wouldn't be what I would call a "desired setup" and yes there are arguments for both but, if you want to be precise (like vacuum adjusting) an adjustable setup would be desired. I also like the adjustment on the rocker cup. Mainly because it is easier to use and is the most common way of adjusting on a GM platformed SBC no matter the Gen., solid roller or not.

[schufflerbot]

thanks for all the help, guys.

one more thing... can anyone accurately describe what 'valve float' would feel/sound like?

[Kingsize]

Valve float is when a valve spring fails to close the valves and the valve comes out of contact with the camshaft lobe during the valve closure phase of the camshaft cycle allowing them to "float".

I doubt that's your problem as floating valves generally result in valve-piston contact with subsequent destruction of your engine.

[schufflerbot]

Valve float is when a valve spring fails to close the valves and the valve comes out of contact with the camshaft lobe during the valve closure phase of the camshaft cycle allowing them to "float".

I doubt that's your problem as floating valves generally result in valve-piston contact with subsequent destruction of your engine.

hrmmm. ok.
thanks.

[Kingsize]

Trust me there would be a ton of slop that you would notice. If the spring doesn't fully close the valve. Then the rockers, push-rods, & lifters would all be out of contact with each other intermittently. It would cause all kinds of noise, enough to where you would know it wasn't simply a slightly longer push-rod.

[camarochevy1970]

Trust me there would be a ton of slop that you would notice. If the spring doesn't fully close the valve. Then the rockers, push-rods, & lifters would all be out of contact with each other intermittently. It would cause all kinds of noise, enough to where you would know it wasn't simply a slightly longer push-rod.

yeah, I agree, no way you are getting valve float and not noticing that.

[Konnie the Goat]

Not to mention float is usually an upper rpm thing.

This has got to be a pushrod issue.

[E.T.M.C.]

ok, good.

well, not good.. but reassuring, LOL

everything in my head and what ive researched tells me the PR length is wrong. i need to get my oil pressure gauge put in so i can rule that out, too.

thanks, man.


7.4 on all TQV2's i have ever done. unless they mis marked the pushrods. you have to use the longer pushrod cause of the comp cam base circle being smaller. but you should have 7.4's in there

[schufflerbot]

7.4 on all TQV2's i have ever done. unless they mis marked the pushrods. you have to use the longer pushrod cause of the comp cam base circle being smaller. but you should have 7.4's in there

i do have 7.400 length pushrods in there right now. that's the thing, when i had the LS1 lifters in there, when i drove it home on one bad lifter, it sounded really loud and crazy... but it was very distinctly ONE lifter making the noise - the rest were quiet.

only when we put the LS7 lifters in did this noise start up with all of them. it still sounds like its one or two that are making more noise than the rest, but its really hard to tell, as its random.

looking at the pic below, you can see that the LS7 lifter cup is WAY closer to the end of the lifter than the LS1 lifters. all other variables remained the same, so wouldnt that mean i would need to shorten the pushrods?

http://www.ls1tech.com/forums/attachments/generation-iii-internal-engine/183512d1244755163-pushrods-ls7-lifter-question-ls7-20lifter-20comparison.jpg

[schufflerbot]

*bump for the mystery*

[camarochevy1970]

what did you find out?

[schufflerbot]

what did you find out?

i called the guy who just replaced my lifters and he told me the only thing wrong with them was that 2 of them were facing the wrong way. this, in my opinion, was causing a lot of noise since they werent being oiled correctly which made sense. i asked him about changing the pushrods and got kind of a 'i wouldnt do that, the 7.4s are fine' vibe from him - he is kinda vague though...

from my last post, the one with the pics, it would seem to me that i have one option left - to change out the PRs to reduce the preload.

judging from what Stephen said about 7.4s being the correct PR for the LS1 lifter, i can only assume that changing to LS7 lifters is going to need shorter pushrods.

*shrug*

im gonna just change em this week and see what happens.

[schufflerbot]

UPDATE!

put the 7.35 pushrods in last night and said a little prayer. started her up and she sounded great. let her warm up for 5-7 minutes, no clacking.

got her out on the road, everthing seemed great. took her up to 4500 rpm for a 2-3 'pull' to get the oil heated up and i heard what i have thought all along was what the valvetrain was supposed to sound like...

a sewing machine. lol

the clicks are nice and even now, theyre not overbearing and although i can still hear the exhaust leak, the thing sounds incredible. i am still having problems with the engine seeking an idle spot and when it drops down to ~500 rpm for a second, i get the 'low oil pressure' warning chime. im thinking the exhaust leak is causing the idle to seek like that and messing with the AFR. i know when it was tuned last, the pushrods were too long and it was running like crap.

next step is to get the exhaust leak taken care of and a retune.

*phew*

[Lancer-AM]

Glad the pushrods helped. Sucks when something is wrong and you are having to take stabs in the dark.

[Kingsize]

Sounds good Schuff.

[schufflerbot]

any thoughts on the exhaust leak contributing to the idle/AFR issues?

[LILGTO]

I think it is in your tune.

[Kingsize]

The leak will affect the idle some but not a whole lot. You should fix that issue first and then get your tune corrected.