PREDATOR-Z

In your initial post heads are unmilled and with a MS4 and .054 gasket this makes no sense.
Unless heads are milled.
If this measurement is correct (7.350), somewhere in this post you omited or misposted some info.
What lifters were you using? (in case I missed it)

bayer-z28

iTrader: (14)

Heads are not milled.
Since we yanked the heads again to replace the STOCKERS w/ LS7 lifters, we replaced the head gasket also. It's a thinner GM head gasket, .040~ something.

-=Modified=-

iTrader: (3)

Heads are not milled.
First set of gaskets were .054 (12498544 - 2002-2003 LS1/LS6 Head Gasket). New gaskets are 12498543 which I think are 0.040 thick (12498543 - 1997-2001 LS1 Head Gasket)
I think using the .054 head gasket threw everything off although they were the same head gaskets as stock. Hopefully I will have better luck with the thinner gaskets.

BigKap94z

iTrader: (47)

From my research the 12498543 gaskets have a compressed thickness of 0.056". I could be wrong but it would be worth it to recheck.

98Camarod

iTrader: (43)

Why would they have to recheck, they used a pushrod checker?

PREDATOR-Z

BTW there is no GM gasket with .040 thickness on LS1 motors.

12498543 is the graphite gasket with average .054 thickness

Still doesn't make any sense, unless the LS7 lifters are .050 (at least) taller than stock lifters from roller to cup.

bayer-z28

iTrader: (14)

^ I ASKED for LS7 Lifter dimensions on another thread and the ONLY response I got was someone told me they were identical.

IF the lifters are taller, you should need a shorter PR to maintain the correct length. Same goes w/ if you have a thinner HG, you would need a slightly shorter PR.

The adjustment that we came up w/ (PR length) we both agreed w/. I felt comfortable w/ the decision to go w/ the 7.350's. 7.300 was right at Zero, so we added the .050 for preload.

-=Modified=-

iTrader: (3)

I think you are right about the gaskets. It looks like 543 and 544 are both .056. Not .054 which was a guess. I couldn't remember the exact thickness. Perhaps the 12498543 compresses better than 12498544. When you compare the two, and should have taken pics, the 543 is a lot more pliable and softer than the copper feeling 544. Who knows.
I finally have pushrods that are the correct length and my brain is fried from trying to figure all this stuff out.

Here is what is in the car now



...and stock and the replacement I used previously

bayer-z28

iTrader: (14)

!!PROBLEM SOLVED!!

We got the car back together. -=Modified=- and Myself, his car.

Parts Replaced were:
-LS7 Lifters
-New Head gaskets (new bolts too for that matter)
-New thicker O ring for oil pickup tube.
-7.350 PR's. (checked w/ PRLchecker)

Other than the sound of 8 grannys knitting an afghan under the hood, the valvetrain knock is GONE! The oil pressure no longer fluctuates at idle. it sits firm at 60psi w/ the ported pump. Everything works great!

I think that little bastard of an O ring did the trick!

98Camarod

iTrader: (43)

Glad to hear it finally worked out.

-=Modified=-

iTrader: (3)

The cure:
After a TSP MS4 cam and PRC S1 heads with all the options swap I had a very loud knocking coming from piston 7. The bottom is a stock LS1 346.
To make a very long story short here is what was installed that rid the car of knocking.

1. Thicker oil pump o-ring GM# 12557752
2. LS7 lifters GM# 12499225
3. Head gasket GM# 12498543 (Stock was 12498544)
4. TSP 7.350 chromemoly pushrods TSP# 25-7350


FYI
GM BOLT KIT GM# 12498545

TSP LS6 Oil Pump
Stock timing chain
Stock rockers torqued to 22 lbs ft

99blancoSS

iTrader: (115)

Glad you got it right. Nothing sweeter than a tick free valvetrain.

Was pr length ever checked and a swipe pattern verified in the first place?

There is a good sticky for cam swaps to be had here. Some basics that often get over looked because of the hydraulic lifters is my guess. Pre-load or "crush" is more critical than is ever emphasized it seems.

I wasnt real techinical when I checked mine but I did make sure how much "crush" I should have. I verified with LME and checked it by feel. (number of turn to seat the rocker). I had the valve cover off recently and decided to verify it more accurately. It was dead center on the swipe and comp cam pr checker verfied that 7.4 was the correct length. I used the #2 cylinder, easiest one to get to.

bayer-z28

iTrader: (14)

^ yeah, we used the PR Length Checker. Adjusted it to 7.300, then installed it. I ended up backing the PRLC out a little then on the tightening sequence we managed to find zero lash. It was a delicate procedure on dry lifters. After checking and rechecking a number of times, the Zero ended up being 7.300. After we were both happy w/ it, we added .050" for preload. We just happened to have a set of 7.350" PR's, so we threw them in.

What do you mean by "swipe pattern"? I might have missed that post.

brad8266

iTrader: (23)

Swipe pattern is the wear pattern on the valve stem from the rocker contacting it. It should be centered on a properly set up valvetrain.

bayer-z28

iTrader: (14)

^ Huh.. We didn't check that. When the rockers were installed we tried to ensure the rocker tips were centered on the valve stem tips.

We can allways recheck easy as yanking a VC to take a look...

Paging Jason!

brad8266

iTrader: (23)

if you measured the PR's and everything your wipe pattern is most likely just fine. I wouldnt bother checking it again. You guys did what most people are to lazy to do. Thats cool that you got a quiet valvetrain now.

99blancoSS

iTrader: (115)

Just take the rockers off the #2 cylinder and use a black marker and color the tips of the valve stems. Then torque the rockers back into place and turn the motor over a few times by hand. Then take the rockers off and look for the where the marker is worn off the valve stem. It should be centered. Like Brad said your most likely fine. But if you wanted to, thats how you do it.

bayer-z28

iTrader: (14)

^ Thanx do0d.. Now I know..

blacksi

iTrader: (3)

Hey guys, quick question. I just installed a trex with 921 duals. I've only run it for 20 or 30 secs and it was very noisy. Will this possibly go away once the motor has run for a while, or should it instantly be quiet? I am going to pick up a new belt tomorrow and was hoping once it warmed up that maybe the lifters would fill or what ever. stock heads with 7.4 PR's recommended by thunder racing.

If I didn't touch the oil pump and never had noise before, is it safe to assume it's not the oring?

SLPRC5

Try a set of Cadillac Raceing Lifters part# 88958689 they have been said to quiet down the sewing machine sound after cam upgrade..