Lifter noise with cam
Thread Starter
Racer
Joined: Aug 2010
Posts: 349
Likes: 7
From: San Diego CA
Lifter noise with cam
I swapped the mildest truck cam from comp, z06 valve springs, LS2 timing chain, and a 25% UD pulley in my '01 LS1. It runs fine and pulls exactly as I expected, but it developed a pretty loud lifter knock when warm. The valve train has the usual Singer tick when cold, but after a few hard pulls it starts knocking so hard at idle that it can be heard hood closed. The knock sounds like a lifter knock as opposed to rod knock.
I was being careful with the oil pick up O-ring, but the oil pressure when hot is at 25psi at idle (60 at max).
I used stock rods and rockers, and tried to torque them properly.
The idle is very lopy when hot, smooth when cold.
The oil is 5w30 Mobil 1.
The engine has 55000 miles on it.
Ideas to start debugging this?
I was being careful with the oil pick up O-ring, but the oil pressure when hot is at 25psi at idle (60 at max).
I used stock rods and rockers, and tried to torque them properly.
The idle is very lopy when hot, smooth when cold.
The oil is 5w30 Mobil 1.
The engine has 55000 miles on it.
Ideas to start debugging this?
Last edited by T5Mika; Sep 23, 2017 at 11:41 PM.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Is the noise coming from all the lifters or can you isolate to one or two? If one or two, check those rockers for any abnormalities. Check and make sure that oil is coming up the pushrod. If you used stock pushrods, roll them on a flat surface and make sure they are straight.
Could be many things, but I found even as careful as I was during my first cam swap I got one small dirt fragment in the oil gallery for the lifters. Only found it because I had borrowed an articulating borescope from work. So an small dirt particles (pieces of gasket, etc.) that might have gone into the lifter gallery can cause this issue.
Could be many things, but I found even as careful as I was during my first cam swap I got one small dirt fragment in the oil gallery for the lifters. Only found it because I had borrowed an articulating borescope from work. So an small dirt particles (pieces of gasket, etc.) that might have gone into the lifter gallery can cause this issue.
Pro
Joined: Mar 2004
Posts: 714
Likes: 104
From: Springfield Ohio
A new cam will normally require careful measurements to determine the correct pushrod length for that particular cam. Chances are pretty good that the stock pushrods are too short for your build. In some instances, the exhaust pushrods will be slightly different than the intakes. Get a good pushrod checker and measure them so you know exactly what length you need. pushrods can be purchased in any required length. You'll also need an 8 inch caliper to read the measurements obtained. Without accurate measurements, you're just guessing.
Thread Starter
Racer
Joined: Aug 2010
Posts: 349
Likes: 7
From: San Diego CA
Now I'm starting to suspect exhaust leak...
I had to loosen the H-pipe to manifold flange to remove a starter bolt. The exhaust snaps and creaks now in hard acceleration, and the tap tap tap sound is louder under the car. The rockers sound ok with a stethoscope. I bet the exhaust is not properly seated. I think I'll try the old seafoam trick to see if the flange leaks.
I had to loosen the H-pipe to manifold flange to remove a starter bolt. The exhaust snaps and creaks now in hard acceleration, and the tap tap tap sound is louder under the car. The rockers sound ok with a stethoscope. I bet the exhaust is not properly seated. I think I'll try the old seafoam trick to see if the flange leaks.
Melting Slicks
Joined: Nov 2008
Posts: 2,938
Likes: 65
From: Rochester Hills MI
if pushrod length is not an issue, I would give it time. sometimes air can get trapped inside the lifters and takes a while to work its way out. This is why a lot of people suggest soaking the lifters first.
Last edited by SaberD; Sep 28, 2017 at 12:23 PM.
