I Confederate I

Sorry to repost this, but it got bumped down so fast I don't think anyone saw it.

I have an 01 LS1 with a TSP 233/239 cam, roller rockers and lifters. Lately driving on the highway has introduced a valve tap on the drivers side, usually after cruising at highway speeds for a decent amount of time. Of course when I first heard it I started to think it was a valve adjustment issue...but it goes away after I let it idle for a minute. It has been come and go, usually only appearing on the highway. Now I'm starting to think it could be a lifter is going, but they are relatively new. The pushrods were swapped to the correct sizes when the cam and lifters were installed. Ideas? I'm trying to see if I need a day to adjust the valves, or a weekend to pull the heads. Thanks guys.

Darkman

iTrader: (2)

Do you have adjustable roller rockers? What preload are you running?

I Confederate I

Yes I have adjustable roller rockers and roughly .030" preload

Darkman

iTrader: (2)

What lifters do you have?

I Confederate I

Honestly, I don't know. The man I bought the car from installed the rockers and lifters as part of his "cam prep" but never installed the cam. He was...interesting. I had the cam installed by a local shop, as well as the correct pushrods.

Darkman

iTrader: (2)

Different lifters require different preloads, particularly for quiet operation. Morels, for example, use 0.030" to 0.0.050" and seem to be quieter toward the upper end of that range. OEM lifters, including the LS7 lifters that are now the standard replacement lifter, have a operating range that runs as high as 0.100". I think you probably could use more preload, but without knowing what lifter you run it is hard to say.

I Confederate I

Im planning on pulling it apart tonight. Ill look and see if I can recognize them. My problem at the moment is that my torque wrench is my trusty forearm. Could that cause my intermittent tapping though? It seems like a low preload would cause a constant tapping. Im not really up to date on new valvetrains though.

crainholio

iTrader: (2)

Is buying a torque wrench just out of the question? If you're going to work on an aluminum block LS engine, it'll save you a lot of headache. Cheaper than timesert thread replacements too.

I Confederate I

I guess its not. Ill look into one tomorrow. What's the setting for roughly .040"? I would estimate around 22-24ft-lbs?

crainholio

iTrader: (2)

Wow. If you're running stock pedestal-type rockers, the preload is established by pushrod length. Rocker bolt torque just holds the rocker in place.

Darkman

iTrader: (2)

You indicated above that you have adjustable rockers. Assuming that is the case, the preload is adjusted using feeler gauges and the adjustment screw/lock nut on the pushrod side of the rocker. If you are not setup to do this adjustment I would let the shop do it.

I Confederate I

Sorry I don't know these things. My last drag car was an 81 z-28. We just tightened them down a quarter turn after the tapping stopped. Ill check around and see what the prices are like. I guess socket wrenches don't do the work they used to.

Still though, I never heard back about this causing an intermittent tapping. Does incorrect preload do this? I feel like that would be a constant tapping.

Well it was definitely a lifter. I did a stress test on all of them today and my #7 intake lifter collapsed. Apparently that guy didn't replace the lifters like he said he did. Go figure. Trust a stupid stranger. The old lifters had quite a few miles on them and couldn't handle that large cam. Oh well. Time for a lifter job. Goin big Sammie will love her new look.