crash41301

iTrader: (1)

Heres the back story...

I had a running Ls1 w/ BTR Stg2 cam. It had oem GM ls7 lifters in it with 7.5 pushrods, and TFS220 heads. It had zero sewing machine noise to it. It was great.

I ended up with a wiped bearing after a road course day due to not realizing that I should run extra oil in the pan due to long sweepers. I ended up rebuilding the engine. The cam was in good shape so I re-used it. I went with Delphi ls7 lifters this time thinking they would be the same thing. I now have a running healthy engine, but with sewing machine noises. Everything else is the same. I thought, ok perhaps its the pushrod length.

Measuring the pushrod I get 7.38 with no preload and being able to rotate the pushrod in place. Ive read that I should aim for .06-.07 preload on the ls7 lifters. That would put me at 7.44-7.45.

So my question is, is that additional .05 enough to cause sewing machine noises? Ive saw some people suggest running .1 preload on them to "avoid excess valvetrain noise". It seems I have excess already. Where should I be trying to set these things? I want my silent valvetrain back that I had before the rebuild!

TrickFlowTech

The exhaust lobe acceleration rate has more of an effect than anything. If you didn't have noise before, it won't this time around.

slogo

Do you know if post #6 is correct https://ls1tech.com/forums/generatio...s-lifters.html

G Atsma

If that were true, why do the lifters all have the same part number? If somebody had to replace a lifter there would be different numbers for intake and exhaust lifters. That is not the case.

slogo

Yeah, Thank for the response but I wasn't asking the Village Parrot,
was looking for a response from someone with a little Merit.

G Atsma

I forgot, Slogo, logic does not apply to you.... get back on the short bus....