Extremely noisy lifters after cam swap (new LS7 lifters) 2008 SSV

[MrPtnt]

The guy looking into it was busy and will call me back - so no progress yet. So far, VCM has been very good to deal with, so hopefully it stays that way.

If anyone has any tips of what I should be looking at next, please let me know so that I can diagnose in parallel. The push rods seem to be the right length, and the few I have pulled out aren't bent, and the rockers appear to be stock (I cannot see any markings on them indicating that they arent), so I really have no idea what would cause this. There was oil in the rocker cover and on the parts (so it is not bone dry).

 

[Pollushon]

Did you just whack the 7.4 rods in without measuring first? Incorrect preload will kill your valvetrain pretty quickly

 

[MrPtnt]

I didn't measure with a tool, but from zero lash on the 7.4 rods I have just over 1 full turn to fully torqued, which I believe is normal?

 

[Pollushon]

Measure by turn is a really unreliable way to set preload, so many factors come in to play. Theres only .04 to .110 to play with on ls7 lifters, I can never stress enough how important measuring is.

I hope it ends up faulty kit mate but a comp cams 7702-1 pushrod length tool is a solid investment.

 

[delcowizzid]

1 turn assuming 1.5mm thread pitch he' should be way under the max travel

 

[delcowizzid]

Assuming he found zero lash correctly or if the lifters crushed down it could be a lot more

 

[blackve76]

hopefully you find the issue is cam timing correct???

Generally I've found cam installs required longer rods 7.425 dur to new cams smaller base circle. So 7.4 rods should be fine if all stock motor(heads not shaved.

 

[MrPtnt]

OK, so some of the information my mechanic gave me was misleading. Oil is getting up to the rockers, it was just that he was expecting it to spray out heaps (which it doesn't on these).

I have started to try to diagnose myself over the weekend, and I observed that all of the rockers were tight and appeared to have an appropriate pre-load.

I had the car running yesterday, and the very loud lifter noise suddenly disappeared, but started running like it was down a cylinder. (it is hard to tell, because it now has a big cam and no tune, so is pretty rough).

I pulled the rocker covers, and one of the lifters appears to have collapsed :-( The pushrod isnt even touching the rocker (it is at least 1mm gap), meaning that I can move the rocker up and down quite a bit before it touches either the valve or the pushrod. In other words, it is like the pushrod is way to short... It was not like this when the engine was very noisy.

The pushrod is straight, and no signs of damage.

The funny thing is, the engine isnt nearly as noisy as it was now - I would have expected massive play in the rockers to be very noisy.

I guess I will have to remove the heads, but I still have no idea what went wrong...

 

[Pollushon]

Everything you've described above suggests you have an issue with valve train geometry. The LS is a non adjustable setup, literally the only way to adjust a stock system is via pushrod length. The only flex the valvetrain has is .220 plunger travel on the LS7 lifter and you wanna be somewhere in the middle. That's why I tend to harp on about the preload thing, it's all you have

We have no idea what other bits might have changed when you refreshed the top end but here's a few geometry culprits to jog your memory:

Change in valve stem length (new valves a grind or even a lap)
Facing the head
Decking the block
Non standard head gaskets (like Cometic)
Remanufactured rockers
Stretched rocker bolts or worn rocker mount plates

Anything sounding familiar?

 

[MrPtnt]

I didn' grind or lap the valves, face the head or deck the block. I used a GM head gasket set.

The car/parts didn't leave home, so none of this happened without my knowledge.

There may of course be wear in the rocker plates, etc, but that wear would've been there before the new lifters.

What I don't really understand now is that the car now sounds much better, it doesn't have that horrid knocking noise.