Pushrod length driving me crazy!
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
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From: Mc Farland Wisconsin
Pushrod length driving me crazy!
Hey guys,
Im at witts end here with my personal patience. Heres the scenario....2000 coupe, stock 853 heads, TSP 228r cam, 7.4 pushrods, stock rockers. I have put like 100 miles or so on the setup and I understand there will be more noise, but theres no way this much noise is to be considered normal. It is really bad just after startup, and then once the car is nice and warm at idle and yesterday I noticed while at cruising through a neighborhood while it was real warm that every car I passed all I could hear is LOUD valvetrain noise. I feel dumb asking, but I figured its better to ask than to keep driving on this setup if something is wrong.
I have read plenty of threads on this, read the comp-cams write up and it still just doesnt make sense completely.
I am using a comp cams pushrod length checker I bought with my cam setup from Texas speed.
Here is my fantastic drawing of what the wipe looks like on the valve.
black section is where the marker stayed. Sorry that its out of order, but they are correctly labeled.
Actual photo of 7.45"
7.35"
And last but not least, the original 7.4"
Ideas????
Im at witts end here with my personal patience. Heres the scenario....2000 coupe, stock 853 heads, TSP 228r cam, 7.4 pushrods, stock rockers. I have put like 100 miles or so on the setup and I understand there will be more noise, but theres no way this much noise is to be considered normal. It is really bad just after startup, and then once the car is nice and warm at idle and yesterday I noticed while at cruising through a neighborhood while it was real warm that every car I passed all I could hear is LOUD valvetrain noise. I feel dumb asking, but I figured its better to ask than to keep driving on this setup if something is wrong.
I have read plenty of threads on this, read the comp-cams write up and it still just doesnt make sense completely.
I am using a comp cams pushrod length checker I bought with my cam setup from Texas speed.
Here is my fantastic drawing of what the wipe looks like on the valve.
black section is where the marker stayed. Sorry that its out of order, but they are correctly labeled.
Actual photo of 7.45"
7.35"
And last but not least, the original 7.4"
Ideas????
Last edited by Nver2loud; Apr 25, 2012 at 10:13 PM. Reason: dam pictures!
Melting Slicks
Joined: Mar 2002
Posts: 2,203
Likes: 63
From: Staten Island NY
I also have a TSP 228R with PRC stage 1 heads.
I didn't check the wipe pattern. I did use the pushrod checker. What I did was simply install one rocker arm on the number 1 piston while the lifter was on the base circle of the cam. Torqued the rocker to 22 lbs and turned the checker until it was snug - Had to remove the checker and turn it - and replace the rocker a few times. It came out to 7.350
I did this on a few different cylinders.
ALSO - due to the difference in the cam profile Vs stock, there will be increased valve train noise.
The dreaded sewing machine sound.
You did replace the springs and maybe the trunion upgrade right?
I didn't check the wipe pattern. I did use the pushrod checker. What I did was simply install one rocker arm on the number 1 piston while the lifter was on the base circle of the cam. Torqued the rocker to 22 lbs and turned the checker until it was snug - Had to remove the checker and turn it - and replace the rocker a few times. It came out to 7.350
I did this on a few different cylinders.
ALSO - due to the difference in the cam profile Vs stock, there will be increased valve train noise.
The dreaded sewing machine sound.
You did replace the springs and maybe the trunion upgrade right?
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
Likes: 0
From: Mc Farland Wisconsin
Springs are PAC 1218, no trunion upgrade. The noise is annoyingly loud and actually seems to be getting louder.
With your PRC's are they milled at all causing a need for the shorter pushrods?
With your PRC's are they milled at all causing a need for the shorter pushrods?
Melting Slicks
Joined: Mar 2002
Posts: 2,203
Likes: 63
From: Staten Island NY
I have the same springs, heads are not milled.
I doubt it make much of a difference in performance, there is a variance in lifter preload. (Between 7.350 and 7.400)
Try and take another measurement buy setting to Zero lash and see if its still 7.4
My car also sounded MUCH different before getting a dyno tune. (engine noise wise - ) Are you replacing those heads soon?
I doubt it make much of a difference in performance, there is a variance in lifter preload. (Between 7.350 and 7.400)
Try and take another measurement buy setting to Zero lash and see if its still 7.4
My car also sounded MUCH different before getting a dyno tune. (engine noise wise - ) Are you replacing those heads soon?
Safety Car
Joined: Jul 2005
Posts: 3,572
Likes: 9
From: Jackson Tn
St. Jude Donor '06-'07-'08-'09
stock rockers do not stay in the center of the valve stem. They start on the inside and roll to the outside. This is the reason when you get over .600 lift most go to roller rockers.
Here is a thread with some great info on preload. Look at post #10 about how Shane @ Thunder Racing sets his, it works
http://ls1tech.com/forums/generation...g-machine.html
Here is a thread with some great info on preload. Look at post #10 about how Shane @ Thunder Racing sets his, it works
http://ls1tech.com/forums/generation...g-machine.html
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Pushrod length will not alter the wipe pattern. Your wipe patter, and in general terms, indicates the rockers might need some lowering. However, you will not get the tight centered pattern with the stock rockers. That being said, headers will also add to the noise.
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
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From: Mc Farland Wisconsin
Ok, so the wipe pattern doesnt matter much? I guess what I'm wondering currently is if my 7.4's are too long? I have read some threads about lifters having too much preload and something about them bleeding down while running. How would the headers add to the valvetrain noise? Theyve been on the car since before I bought it, and I had no noise prior? Whats the best way to try to get to zero lash with these? Trial and error with the length checker? Whenever i put the rocker back on, it does seem to crank the valve down quite a bit, is this normal?
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
Likes: 0
From: Mc Farland Wisconsin
stock rockers do not stay in the center of the valve stem. They start on the inside and roll to the outside. This is the reason when you get over .600 lift most go to roller rockers.
Here is a thread with some great info on preload. Look at post #10 about how Shane @ Thunder Racing sets his, it works
http://ls1tech.com/forums/generation...g-machine.html
Here is a thread with some great info on preload. Look at post #10 about how Shane @ Thunder Racing sets his, it works
http://ls1tech.com/forums/generation...g-machine.html
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Melting Slicks
Joined: Nov 2008
Posts: 2,938
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From: Rochester Hills MI
Safety Car
Joined: Jul 2005
Posts: 3,572
Likes: 9
From: Jackson Tn
St. Jude Donor '06-'07-'08-'09
Wow, thats a good write up that really makes sense! I took a rocker off and used the 7.4's that are in the car, tightened it back down at 1.5 turns till it was toruqed. Now, using their calculation of .047 per turn, that puts me at .070 preload. Not sure if thats too much or not?
you can try a different length PR to get it down to 1 1/4 turns and see if that makes less noisey
Make sure you are on the botton of the lobe on each valve when you torgue them.
Last edited by printmanjackson; Apr 26, 2012 at 12:25 PM.
Drifting
Joined: Jun 2010
Posts: 1,349
Likes: 3
From: US
^ This is good info.
Also read this:
I followed this setup and I got 7.425 Pushrods but I have PRC 2.5 LS6 Heads Milled @ 62.5cc with a 232/238 599/601 113 LSA cam. Definitely use this method and you will have a happy pre-load and a better overall valve train geometry.
Make note that if you are hearing a lot of valvetrain noise and the "sewing machine" sound is excessive then you probably are running too short of a pushrod. I was running 7.400 for a little bit and the sewing machine sound was pretty loud. I went through the steps above and moved up to a 7.425 and I still have the sewing machine noise but it's very, very light. Good luck man 
Also read this:
Originally Posted by XtraCajunSS
FWIW, EVERY cam install I have done using the LS7 lifter with a cam with greater than .600" lift (read smaller base circle) AND stock heads w/GM MLS gaskets has taken 7.425" pushrods for ~.050"-.060" preload. We measure lifter preload on each and every cam install we do. I have never had a lifter failure nor do we end up with the dreaded "sewing machine" noise.
Its very simple, If you change ANY of the following:
valve sizes, valve job, head milling, thinner/thicker head gaskets, decked block, cam with an altered base circle, etc... YOU MUST CHECK FOR PROPER PUSHROD LENGTH.
I have helped countless numbers of individuals with this process over the phone, via email, and PM's. I've posted the process on at least 3 occasions.
Here it is again in a nutshell:
1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.
For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...
I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.
If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.
THIS METHOD ALWAYS WORKS!!!
I hope this helps someone. I have explained it so many times I think I do it in my sleep!!!
Shane
FWIW, EVERY cam install I have done using the LS7 lifter with a cam with greater than .600" lift (read smaller base circle) AND stock heads w/GM MLS gaskets has taken 7.425" pushrods for ~.050"-.060" preload. We measure lifter preload on each and every cam install we do. I have never had a lifter failure nor do we end up with the dreaded "sewing machine" noise.
Its very simple, If you change ANY of the following:
valve sizes, valve job, head milling, thinner/thicker head gaskets, decked block, cam with an altered base circle, etc... YOU MUST CHECK FOR PROPER PUSHROD LENGTH.
I have helped countless numbers of individuals with this process over the phone, via email, and PM's. I've posted the process on at least 3 occasions.
Here it is again in a nutshell:
1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.
For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...
I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.
If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.
THIS METHOD ALWAYS WORKS!!!
I hope this helps someone. I have explained it so many times I think I do it in my sleep!!!
Shane
Make note that if you are hearing a lot of valvetrain noise and the "sewing machine" sound is excessive then you probably are running too short of a pushrod. I was running 7.400 for a little bit and the sewing machine sound was pretty loud. I went through the steps above and moved up to a 7.425 and I still have the sewing machine noise but it's very, very light.
Good luck man
Safety Car
Joined: Apr 2004
Posts: 3,932
Likes: 8
From: Hayward California
How many turns did you get with 7.35? Try using what ever gives you 1 turn. You can also shim the rockers to get you to a turn. You can also try a slightly thicker oil.
Headers definitely make valvetrain louder.
Headers definitely make valvetrain louder.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Wow, thats a good write up that really makes sense! I took a rocker off and used the 7.4's that are in the car, tightened it back down at 1.5 turns till it was toruqed. Now, using their calculation of .047 per turn, that puts me at .070 preload. Not sure if thats too much or not?
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
Likes: 0
From: Mc Farland Wisconsin
I have been receiving conflicting info on this, which is kinda why I was not opting for a cam swap in the first place. I figured with something like a texas speed 228r so many people had one that everything like pushrod length should be worked out. Hard to say which method is the tried and true method, and the only way to see if it works is trial and error.
I have heard the header thing from many people, but I have had headers on my car for 40k miles and never had any noise like this. Its so loud, it actually sounds like a rattly POS going down the road. I have heard plenty of other cammed cars, and there is no way this can be considered normal.
I have heard the header thing from many people, but I have had headers on my car for 40k miles and never had any noise like this. Its so loud, it actually sounds like a rattly POS going down the road. I have heard plenty of other cammed cars, and there is no way this can be considered normal.
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
Likes: 0
From: Mc Farland Wisconsin
Here is a very long thread that may answer a few questions: Link
I dont mean for any of my comments to sound ungrateful, i do appreciate any and all feedback.
Thanks again
Thread Starter
Pro
Joined: Apr 2007
Posts: 635
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From: Mc Farland Wisconsin
Yeah...They told me that it may be possible my pushrods are not the correct length and to check my preload, they said neighborhood of .060-.070 but there is some cushion as to what they will tolerate. Didnt really do much for me if I cant find out a way to really see what exactly I have for preload.
I will have to give them a call tomorrow if I get time. Ive come to the conclusion that for the tiny increase in power that can be felt with my minimal tuning yet, its not worth the noise. I am afraid its setting off my knock sensors becuase im getting quite a bit of KR at some spots.
I will have to give them a call tomorrow if I get time. Ive come to the conclusion that for the tiny increase in power that can be felt with my minimal tuning yet, its not worth the noise. I am afraid its setting off my knock sensors becuase im getting quite a bit of KR at some spots.
Burning Brakes
Joined: Jul 2006
Posts: 968
Likes: 12
From: Regina Sask
Does that cam use Comp Cam's XER lobes? Just tuned a 2010 Camaro that had a 227/243 113 .614/.624 LSR Comp Cam, Kooks headers/exhaust and a 102 Fast intake. There was no valve train noise at all. Also there was no low speed buck/surge at all. Quietest cam I've heard on a LS motor.
Now after talking to Comp Cams about the LSL lobes used in their LSR cams, I'm going to swap my G5X3 114 cam for the 227/235/ 113 .614/.621 LSR cam.
The tech said I probably won't loose much if any top end power over the G5X3 cam, and will gain low load/low RPM drive-ability. And will be quiet because the LSL lobes seat the valves slower.
Russ Kemp
Now after talking to Comp Cams about the LSL lobes used in their LSR cams, I'm going to swap my G5X3 114 cam for the 227/235/ 113 .614/.621 LSR cam.
The tech said I probably won't loose much if any top end power over the G5X3 cam, and will gain low load/low RPM drive-ability. And will be quiet because the LSL lobes seat the valves slower.
Russ Kemp