Is there a easy way to discover which lifter is bleeding down?

[Steve V]

Hi Steve,
I’m running adjustable roller rockers, my question is when you have the adjustable push rod to the perfect length. Then you take it out and check the length with a micrometer do I need to do any adding or subtracting from the mic reading. Before telling the vendor what length to give me?


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A lot of times you will not get the exact length pushrod you need. They usually are in .025 increments. The rockers have a window of adjustment in which they will work and oil correctly. I set the rocker adjuster on the low end, measure and use that number or as close to it as I can get. 1 turn on harland sharps are .050 so 2-3 threads exposed lets you set it at two and have .050 to adjust your preload with. I hope this makes sence--LOL---maybe we can get some guys with better words to chime in and further explain

 

[Steve V]

I will also add the Harland and T&D's, scorpion maybe different with thread pitch and what 1 turn equals so be sure you are aware of what you are working with.

 

[1972chevy]

A lot of times you will not get the exact length pushrod you need. They usually are in .025 increments. The rockers have a window of adjustment in which they will work and oil correctly. I set the rocker adjuster on the low end, measure and use that number or as close to it as I can get. 1 turn on harland sharps are .050 so 2-3 threads exposed lets you set it at two and have .050 to adjust your preload with. I hope this makes sence--LOL---maybe we can get some guys with better words to chime in and further explain

I'll give it a try. im making up numbers just to explain, lets say you need a 6 inch rod and on your adjustable rocker you have has (.100) up or down for adjustment. now your vendor has a (6.050) rod. this would work. you will back out your adjuster nut (.050) to fit the rod at zero-lash. then you will thread it back in to set preload.
basically you want make sure you have enough threads to set preload and a little left over threads.

 

[84BuickGNYorkPA]

A lot of times you will not get the exact length pushrod you need. They usually are in .025 increments. The rockers have a window of adjustment in which they will work and oil correctly. I set the rocker adjuster on the low end, measure and use that number or as close to it as I can get. 1 turn on harland sharps are .050 so 2-3 threads exposed lets you set it at two and have .050 to adjust your preload with. I hope this makes sence--LOL---maybe we can get some guys with better words to chime in and further explain

Steve,
Yes this is exactly what I do to get the length pushrod I wanted. The T&D has the same thread pitch 20 threads per inch (1 turn = .050) The T&D instructions also call for 2-3 exposed threads (which includes the preload ) I have not asked anyone yet on the preload of the Johnson “Reduced Travel (.096)” Lifters, I believe that this is your preferred lifter too.


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[Jerryl]

. . . . I have not asked anyone yet on the preload of the Johnson “Reduced Travel (.096)” Lifters, I believe that this is your preferred lifter too.

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Pretty sure it's a 0.045" target.

Edit:
If I recall: Set my preload to right around 260 deg rotation @ zero lash to account for expansion and valve seating.

 

[84BuickGNYorkPA]

Thanks Jerryl, once it warms up some I swear I'm going to pull the intake and measure up for the new push rods....

 

[Steve V]

Pretty sure it's a 0.045" target.

Edit:
If I recall: Set my preload to right around 260 deg rotation @ zero lash to account for expansion and valve seating.

Actually some guys run zero preload since it's the only way to very 100% the valve is closing. I don't run over .030 preload on any lifter.

 

[84BuickGNYorkPA]

Actually some guys run zero preload since it's the only way to very 100% the valve is closing. I don't run over .030 preload on any lifter.

Up till now I've always went with 5/8 of a turn or .030 preload, I guess I'll stick with that, thanks Steve and Jerryl !!

 

[Jerryl]

Actually some guys run zero preload since it's the only way to very 100% the valve is closing. I don't run over .030 preload on any lifter.

0.030 is my typical target as well, but ended up shooting for 0.045 following very specific discussions with the manufacturer.