Valve train noise / lifter preload question
07-27-2010, 08:13 AM
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Valve train noise / lifter preload question When I had my LQ4 apart during a swap I noticed a bad cam bearing and journal. I did a full set of bearings (rods/mains/cam) and threw in a low mile pull out cam from a 2002 LS1. I just happened to have it sitting around and it shared the same P/N as the original.
Once I got the motor back together and running I noticed a little valve train noise. Not extremely bad, but enough to make me worry about it's long term reliability. I think it sounds like 1 or 2 lifters that are loose or not pumping up properly.
Since I've been having noise issues I started searching and found most people run .050 to .080 preload on their lifters. I measured the preload from 0 lash and found I had about .60 preload at 1 1/4 turns, however I had much less than the required 22 ft/lbs of torque stated in GM manuals. I have a feeling that going to the full 22 ft/lbs will yield a preload higher than .1. Does this indicate my pushrod length is incorrect? I have a hard time believing that two Gen III cams with the same part number have a different base circle.
Pushrod length appears to be the same between the LQ4 and the LS1 that this cam came from. This is a very basic stock part rebuild, can anyone see what I'm possibly doing wrong?
There's always the chance of having a bad lifter, but I'm trying to rule out all other possibilities before yanking the heads. This motor was a take out from a 1500HD and set idle for about 18 months to a year prior to being installed in my truck. To my knowledge, the top end had never been broken open prior to me.
Long term, I'm looking to do a heads/cam swap, but looking to make this setup live until I get the parts ready.
If the noise was uniform I wouldn't be nearly as concerned, however it sounds like 1, maybe 2, lifters that are loose. I can easily hear it in the cab with windows up. At startup one could definately hear it from over 15 feet. It does quiet as it warms, but never fully goes away. There are some times I drive the truck and can barely hear it, others it's very obvious. It may be my imagination, but I feel that it is getting slightly worse with time. I've driven it roughly 200 miles since the swap was completed. I did also add a set of edelbrock shorties at the same time.
Oil pressure is a solid 45 lbs at hot idle, moving up to 65 when pushing above 3.5k.
Once I got the motor back together and running I noticed a little valve train noise. Not extremely bad, but enough to make me worry about it's long term reliability. I think it sounds like 1 or 2 lifters that are loose or not pumping up properly.
Since I've been having noise issues I started searching and found most people run .050 to .080 preload on their lifters. I measured the preload from 0 lash and found I had about .60 preload at 1 1/4 turns, however I had much less than the required 22 ft/lbs of torque stated in GM manuals. I have a feeling that going to the full 22 ft/lbs will yield a preload higher than .1. Does this indicate my pushrod length is incorrect? I have a hard time believing that two Gen III cams with the same part number have a different base circle.
Pushrod length appears to be the same between the LQ4 and the LS1 that this cam came from. This is a very basic stock part rebuild, can anyone see what I'm possibly doing wrong?
There's always the chance of having a bad lifter, but I'm trying to rule out all other possibilities before yanking the heads. This motor was a take out from a 1500HD and set idle for about 18 months to a year prior to being installed in my truck. To my knowledge, the top end had never been broken open prior to me.
Long term, I'm looking to do a heads/cam swap, but looking to make this setup live until I get the parts ready.
If the noise was uniform I wouldn't be nearly as concerned, however it sounds like 1, maybe 2, lifters that are loose. I can easily hear it in the cab with windows up. At startup one could definately hear it from over 15 feet. It does quiet as it warms, but never fully goes away. There are some times I drive the truck and can barely hear it, others it's very obvious. It may be my imagination, but I feel that it is getting slightly worse with time. I've driven it roughly 200 miles since the swap was completed. I did also add a set of edelbrock shorties at the same time.
Oil pressure is a solid 45 lbs at hot idle, moving up to 65 when pushing above 3.5k.
