Lifter noise (sewing machine noise) Please help!
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 54
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From: CHIMAYO, N.M.
Lifter noise (sewing machine noise) Please help! Installed new cam with small base circle. .625 lift cam. I got 7.400 length PR. And comp 850-16 lifters and Ls9 gaskets w/243 heads. I got that dreaded sewing machine noise now. Kinda comes and goes. My question is would I need a longer PR or shorter to correct my pre load. I also have Harland rockers if that matters. Thanks for any help. The lifters call for .050 preload.
Thread Starter
Staging Lane
Joined: Mar 2007
Posts: 54
Likes: 0
From: CHIMAYO, N.M.
I understand that. But I was asking what I should look for a shorter or longer PR. I have the PR checker. I'm just having trouble getting the right measurement. With the 7.4 pr I had a ill over 3/4 of a turn until 22lbs ft. I thought that would be fine. Guess not. So if I should need a longer rod I will know what to look for. Thanks
I was told the sewing machine sound be because of a performance cam with stocker rockers. Roller tip rockers would eliminate it.
Makes sense because I did measure mine and triple checked. Still have the sound.
Makes sense because I did measure mine and triple checked. Still have the sound.
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Roller rockers may help but it's not likely. If the lifters are good and the PR is the right length then the noise is probably due to the lobe profile causing the exhaust valve to close too fast near 0 lift. This it my issue as I have XE-R lobes. Known for being noisy due to the fast ramp rates.
Based on what you got with the 7.4" rod I too would suggest the 7.425". It should get you to 1.25 turns or so.
Based on what you got with the 7.4" rod I too would suggest the 7.425". It should get you to 1.25 turns or so.
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Staging Lane
Joined: Mar 2007
Posts: 54
Likes: 0
From: CHIMAYO, N.M.
you know,, funny thing is i had a 7.425 in there when i was assembling the engine this past weekend. for some reason i felt more comfortable being under the 1 turn that comp recommends rather then over. the 7.425 were almost exactly 1 1/4 turn over. Now i feel i should have just installed the 7.425. oh well i guess i know what im doing after work.
Last edited by djoif3; Mar 14, 2013 at 09:13 AM.
