lavoy

iTrader: (2)

my block is a stock 4.8 i purchased my heads from texas speed they are the 4.8/5.3 stage 2.5 versions seen here http://www.texas-speed.com/p-1172-pr...ted-heads.aspx.
the only difference is i asked them to install pac 1218 springs instead since im using a z06 cam and lifters i am also using the ls6 rockers and pedistool, the part number on the pedistools between my original truck heads and the ls6 is the same , not to sure on the rockers.
they also suggested hardened push rods and they sent me their 7.400 versions. i am using ls9 head gaskets as well.
any way i started the engine today for the first time and for the first 30 - 45 seconds it sounded fine and then it started clanking in the top end, i never heard lifter clatter in a ls so im not sure but i think it was definitely it. so i removed the push rods and installed the stock ls6 ones which looked a little shorter when side by side and the noise has all but gone away. i can still hear it come and go faintly if i listen real close for it. i tried learning and reading on how to check preload and what we found was that with the 7.400 pushrods and zero lash we got 1.5 full turns on the bolt until 22 ftibs maybe a smidge more. with the stock push rods it was more like 1.25 turns . any way do you guys think the stock push rods are fine or should i go shorter? oh and i asked for the 63 cc version of the heads so i doubt they are cut down much. i kinda wish i would have another ls to listen to to see if the slight noise i hear now is normal or not on these things. thanks for the help in advance.

Darkman

iTrader: (2)

Both push rods put you within the acceptable range for preload (assuming oem lifters) so you should be able to run either.

lavoy

iTrader: (2)

lifters are 04 ls6 the noise was god awful with the 7.400 it startled us pretty bad.

Darkman

iTrader: (2)

Well it sounds like all you need now are some hardened push rods in the same length as you "quieter" length stock push rods.

ZeeOSix

Did you let it warm up to full operating temperature? My LS6 makes a few noises during the first half of warm-up, but once warm it's pretty quiet.

The stock LS1/LS6 (same p/n) pushrods are 7.400" flat-to-flat, which is 7.385" gauge length.

So you're calling the "stock" pushrods the LS6 pushrods ... but you're saying they seem a little shorter than the "7.400" pushrods you were sent? Maybe those aftermarket pushrods are 7.400" gauge length, which is about 7.415" flat-to-flat.

Which lifters are you using?

FYI ... per the "dead 1/3 turn" equation of pre-load:

• 1.5 turns from zero lash to 22 ft-lbs is ~0.091" pre-load.
• 1.25 turn from zero lash to 22 ft-lbs is ~0.072" pre-load.

When I did the valve springs on my LS6 (stock cam, lifters and stock length Manton pushrods), the average number of turns to 22 ft-lbs was 1-1/4 (~0.072" pre-load), and it's pretty quiet.

sfc rick

Does it sound like this?

http://youtu.be/KBEPPUFd0Vw

Edited, After I listened to other youtube postings about valve train noise and heard how horrible those sounded, I don't really have anything to complain about. Guess a little noise is OK after all and expected on some cam applications with valve work included.

lavoy

iTrader: (2)

we did not let it fully warm up at first for a few reasons, number one was the noise it was very odd and the ls1 and ls6 i had in the car before this 4.8 never made any such sounds. and two it had no coolant in it yet we was still going threw the pain in the *** ls coolant fill procedure. the push rods i was sent are stamped 7.400 right on them not sure on where they are measured from however when stood side by side they are definitely longer then my stock ls6 ones by a tad. apon switching to the ls6 ones the noise was all but gone and this remained so threw out the coolant adding procedure and warm up. lifters are 04 ls6 every thing that has to do with the valbe train is from my 04 ls6 block, cam, cam gears, chain lifters ect. according to your chart i am around .072 of preload and i was told the ideal is .040 to .060 so im still a little over.

as for that video mine was worse but i thought i still heard faint sounds of what i heard in my car in that video, the mic makes it hard to hear as clear as in person.

ZeeOSix

They were probably 7.400" gauge length, which would be ~7.415" flat-to-flat length. The LS6 stock pushrods are going to be about 0.015 to 0.017" shorter (7.400" flat-to-flat), which is reflected in the difference in the number of turn you saw with each pushrod.

I'm not sure what the "ideal" pre-load is ... but IMO it's probably closer to 0.060 than to 0.040". Keep in mind too that unless you checked every lifter for pre-load, you could have a few that are much different than others depending on the tolerances of all the components in the system.

lavoy

iTrader: (2)

yeah im going to assume texas speed set the valve height some what equal since they start with new cores and a machine does the valve job and port work. either way i cant help but wonder if going a tad shorter wouldnt be a good thing, i drove the car today for a few miles to check everything out and it seemed to run fine. just not to fond of the slight noise is all.

ZeeOSix

At this point, there's only one way to find out. If you do try shorter pushrods, let us know if it makes a difference.

lavoy

iTrader: (2)

ok spoke to scoggin dickey and they seem to think that the reason the stock length worked fine on my old ls6 is they said gm altered the valve length to make up for the smaller base circle, on my aftermarket heads i probably have standard length valves. either way i ordered some 7.375 gauge length push rods today they will be here tomorrow.