I Need your HELP!!!! Push rods and GMPP/Lingenfelter heads question
01-19-2009, 09:26 AM
#1
I Need your HELP!!!! Push rods and GMPP/Lingenfelter heads question I am having a local mechanic slap a new set of GM's GMPP heads on my 01Z. I recently had a MTI G1 cam, Comp 918 Springs, and MTI chromemoly 7.4" pushrods installed on my car with some other boltons and decided I wanted heads as well. I know that the springs and other hardware will all move over fine, but I seen people running 7.5" push rods and wanted to know if my current push rods would be just fine or will I need to replace those as well.
01-19-2009, 04:47 PM
#3
Thats what I am going to do. The tech says he does not have the tool but if I get it he can test. I seen the tool but how does it work? Do you adjust it to say 7.4" and then bolt the head down and see if anything hits? do you crank the engine by hand??? I would just love to know how it works so I can see him doing it the right way. HAHAHA I am sure he is fine but the knowledge for me would be great.
01-19-2009, 05:02 PM
#4
There are toms of posts on how to use one; better to read then have me explain it.
"Each turn of the pushrod is 0.050". When fully closed, it is 6.800". This is pushrod "gauge length" so you can't measure it directly as the pushrod length is actually based on the length between the ball ends where the ball end measures 0.140" in diameter. Assuming you are using stock rockers or a non-adjustable rocker.
1. Open the adjustable pushrod to the same length as your stock pushrods
2. Close it down two turns
3. Put your rocker rail on the head
4. Make sure you cylinder (typically #1) is at top dead center on the firing stroke so both valves would be closed
5. Put the pushrod in place on the intake valve and make sure it is in the lifter cup
6. Install the rocker and snug down the bolt (don't need to torque, just make sure it is snug)
7. Lift rocker tip up and down, if it "ticks" the pushrod is too short. If you can't easily move the rocker the pushrod is too long.
8. You can try and adjust the pushrod in place buy my fingers are too fat so I end up pulling the rocker and adjusting the pushrod length. Go either shorter or longer 1/2 turn and try again.
9. You are trying to get to the point where the lifter doesn't "tick tick" with the pushrod in place nor is the rocker snug. When you get the pushrod length such that you just barely get rid of the "tick tick", you have found "zero lash".
10. When you have found zero lash, carefully remove the rocker and pushrod without rotating the pushrod.
11. Tighten the pushrod until it is fully closed counting the turns as you go.
To figure out your pushrod length you do the following. Lets assume it took 10-1/2 turns to close the pushrod down to its shortest length after you reached zero lash. Each turn is 0.050".
Your length is then: 6.800" (fully closed length) + 10.5 X 0.050" (number of turns times the length change per turn) = pushrod length minus preload. So for this case:
6.800 +10.5 X 0.050 = 7.325"
This is the length you measured to zero lash without any lifter preload. Now lets say you want to have 0.075" lifter preload, you add that to the measured number and you end up with 7.400" pushrods.
Now repeat for the exhaust valve to verify the length. If you have something like Yella Terra's, it is the same procedure but you must snug down the rocker pair rather than the single rocker." (from vettenuts)
https://ls1tech.com/forums/7957678-post2.html
"Each turn of the pushrod is 0.050". When fully closed, it is 6.800". This is pushrod "gauge length" so you can't measure it directly as the pushrod length is actually based on the length between the ball ends where the ball end measures 0.140" in diameter. Assuming you are using stock rockers or a non-adjustable rocker.
1. Open the adjustable pushrod to the same length as your stock pushrods
2. Close it down two turns
3. Put your rocker rail on the head
4. Make sure you cylinder (typically #1) is at top dead center on the firing stroke so both valves would be closed
5. Put the pushrod in place on the intake valve and make sure it is in the lifter cup
6. Install the rocker and snug down the bolt (don't need to torque, just make sure it is snug)
7. Lift rocker tip up and down, if it "ticks" the pushrod is too short. If you can't easily move the rocker the pushrod is too long.
8. You can try and adjust the pushrod in place buy my fingers are too fat so I end up pulling the rocker and adjusting the pushrod length. Go either shorter or longer 1/2 turn and try again.
9. You are trying to get to the point where the lifter doesn't "tick tick" with the pushrod in place nor is the rocker snug. When you get the pushrod length such that you just barely get rid of the "tick tick", you have found "zero lash".
10. When you have found zero lash, carefully remove the rocker and pushrod without rotating the pushrod.
11. Tighten the pushrod until it is fully closed counting the turns as you go.
To figure out your pushrod length you do the following. Lets assume it took 10-1/2 turns to close the pushrod down to its shortest length after you reached zero lash. Each turn is 0.050".
Your length is then: 6.800" (fully closed length) + 10.5 X 0.050" (number of turns times the length change per turn) = pushrod length minus preload. So for this case:
6.800 +10.5 X 0.050 = 7.325"
This is the length you measured to zero lash without any lifter preload. Now lets say you want to have 0.075" lifter preload, you add that to the measured number and you end up with 7.400" pushrods.
Now repeat for the exhaust valve to verify the length. If you have something like Yella Terra's, it is the same procedure but you must snug down the rocker pair rather than the single rocker." (from vettenuts)
https://ls1tech.com/forums/7957678-post2.html
01-19-2009, 05:22 PM
#5
That my friend is perhaps one of the most knowledgable posts I have ever read regarding my own issues.
I understand fully and it certainly makes sense. I have my stock 7.4" pushrods and I just ordered a pair of 6.350" just in case. Thanks again for that information it is priceless.
Teddy
I understand fully and it certainly makes sense. I have my stock 7.4" pushrods and I just ordered a pair of 6.350" just in case. Thanks again for that information it is priceless.Teddy