perfect777

Okay, the basics:
2005 Cadillac CTS-V
Stock LS6 - 70k miles
Stock 6-speed
Already had Kooks 1-3/4" Headers with off-road pipes

Upgraded the cam to a VRX-4 cam (228/230 .588/.592 112 LSA)
Upgraded to Comp Cam 26918 single springs
Upgraded trunions
New LS7 timing chain
Hardened push rods (7.4" length...I think)

All of these components installed at a local, reputable shop. They also dyno-tuned the car for the new cam as well. Gained almost 30hp total.

When the cam was first installed one of the rockers immediately puked it's needle bearings. This happened before I even got the car out of the shop and they flushed the engine with the heads/oil-pan/headers off. They did a leak-down/compression test and said that everything was normal. When I then received the car from the shop I was very concerned about the increased valvetrain noise (sewing machine sound). I had read that this was somewhat common and was assured by the shop that the sounds were normal for this type of cam and the new valvetrain components that were installed.

Fast forward 1 week and some city driving later...I've put about 250 miles on it. The valvetrain noise is getting louder...especially as I rev. Tonight, as I'm pulling out of my garage after the car has been sitting all day the car wants to drop it's revs and stall right after I let off the clutch to start moving. I can't go forward or reverse without the car wanting to stall. I leave the car in neutral and get out to inspect. The car smells very rich and the exhaust looks almost whitish in color. It also sounds like there is an exhaust leak towards the rear of the engine (although, it's very tough to hear with how loud the engine is and the exhaust note chopping over it).

The car is in the garage now but I was wondering if anybody might have any ideas as to where I could check next to diagnose this problem before taking it back to the install shop.

DMM

Do you know if/how they determined the correct push rod length? Sounds like too much pre-load.

perfect777

No, I don't know the technique that they used (I've been reading up a lot myself on this lately).

NasbaGoat

i was under the impression that if he reused lifters and didnt change heads that stock length pushrods were all that was required

crainholio

iTrader: (2)

edit: It's very unlikely that his new cam has the same base circle radius as the factory cam, given the much larger lobe lift. It would therefore have to be a smaller base circle, which would require pushrods to be longer in order to restore valvetrain geometry and properly preload the lifters.

perfect777

Other than a bad tune, any other likely culprits for what could be causing the engine to stall when I let off the clutch and start feathering the throttle?

Paul57

It definitely sounds like something is wrong with the tune or a sensor with it being that rich.
7.4 rods seem to be preferred for a cam only change but I did talk to an expert that says he uses 7.425 on a cam only change. 7.385 is stock length and the aftermarket cam base circle is typically .025" smaller (radius) from what I have seen and read. With 7.4's you lose .010 preload and with 7.425's you gain .015 preload, if the base circle is .025 smaller (radius).

perfect777

Thanks guys. I'll have my install shop explain the push rod length determination and compare it to the techniques that I've read on LS1tech.

I took the car out for a drive today and it was more of the same. After any form of spirited driving and then coming to a stop and trying to idle in neutral - the car wants to drop it's revs and stall. I have to feather the gas to keep it alive.

A.R. Shale Targa

iTrader: (2)

Check for threads about the oil-pump O-ring being pinched or cracked.FWIW
If the tune was spot on when the engine was seeing the full lift and duration of that cam
and now an oil pressure issue is making the lifters ACT like Rhoades(bleed down) lifters
then the engine will be "seeing" a smaller cam which will build more cylinder pressure,
increase manifold vaccum, and cause it to run rich @ idle.....?????????

95_ls

iTrader: (4)

im having same issues with very similar setup except mine is through an A4 and it doesnt choke out as much......should b interesting to find out what it is

perfect777

A.R. - I have no idea what you are saying...

95ls - I'll let you know how things are going

A.R. Shale Targa

iTrader: (2)

Hydraulic lifters are affected by oil pressure. Recently there was a thread
about noisy valvtrain and after trying several different push-rod lengths
to establish different lifter preloads they figured out that the oil-pump
pickup o-ring was torn causing a leak(hence weak or sporatic oil pressure)
the lifter plungers(where the pushrod meets) then do goofy stuff...move
up and down, cause valvetrain noise, and the engine could run rich and
possibly stall

garygnu

check to see if you IAC is clean. you installed new compcam trunnions bearings on you stock rockers?you need the correct lifter preload,and you want proper valve train geomentry.you want the rocker tip on the middle of the valve stem.

performinnorman

iTrader: (7)

Any updates?

projectX

iTrader: (51)

That makes sense about the oil pump O-ring