Questioning pushrod measurement
03-09-2020, 04:40 PM
#1
Teching In
Thread Starter
Questioning pushrod measurement Hey guys so I’m In the middle of measuring for pushrod length on a fresh stroker build with custom cam (cam motion 239/250 .625/.616 114+4) and Johnson 2116LSR lifters...running 823 heads thatve been milled .020 and a ls9 gasket I’m getting that my zero lash measure is 7.485 (add in preload of .045 & yields 7.53) I kind of feel like that’s too much...anyone able to possible shed some light on what I’m doing wrong here? Thanks in advance 👍🏽
Last edited by 1qwkSS; 03-09-2020 at 04:55 PM.
03-09-2020, 09:22 PM
#4
ModSquad
iTrader: (6)
The 2116LSR requires .035” preload. LS9 headgaskets are .004” thicker than most other GM MLS stuff. Not a lot but everything adds up. So deduct .010” for the preload numbers. Gasket is a constant so it is what it is. What will vary, and is why Ron asked you about calipers, is how your measuring the pushrod checker. You’ll have to do some math to deduct for actual length. Because the check tool doesn’t have oil holes, it will add + or - .017” to the length. An actual pushrod that has the oil holes causes the radius of the tip to be “clipped” at the top, and this number varies on diameter of pushrod and cup style.
Here’s a link to Comps explanation of the process. Your gonna need to be pretty precise with the lifter your running and it’s short preload window.
https://www.compcams.com/valve-train-geometry
Here’s a link to Comps explanation of the process. Your gonna need to be pretty precise with the lifter your running and it’s short preload window.
https://www.compcams.com/valve-train-geometry
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1qwkSS (03-09-2020)
03-09-2020, 10:12 PM
#6
Teching In
Thread Starter
The 2116LSR requires .035” preload. LS9 headgaskets are .004” thicker than most other GM MLS stuff. Not a lot but everything adds up. So deduct .010” for the preload numbers. Gasket is a constant so it is what it is. What will vary, and is why Ron asked you about calipers, is how your measuring the pushrod checker. You’ll have to do some math to deduct for actual length. Because the check tool doesn’t have oil holes, it will add + or - .017” to the length. An actual pushrod that has the oil holes causes the radius of the tip to be “clipped” at the top, and this number varies on diameter of pushrod and cup style.
Here’s a link to Comps explanation of the process. Your gonna need to be pretty precise with the lifter your running and it’s short preload window.
https://www.compcams.com/valve-train-geometry
Here’s a link to Comps explanation of the process. Your gonna need to be pretty precise with the lifter your running and it’s short preload window.
https://www.compcams.com/valve-train-geometry
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03-10-2020, 11:03 AM
#8
Teching In
Thread Starter
My big concern here is that with an aftermarket cam and GM cast heads milled .020 I would think pushrod length SHOULD either be a hair shorter or very close to the stock 7.4...am I out of line with that belief? Even with the .055 compressed gasket I don’t believe I’m far off on that thought process
03-10-2020, 11:30 AM
#10
Teching In
Thread Starter
literally just got off the phone with a Mr. Lewis from Johnson...2116lsr’s have a lower cup height than Delphi’s so the longer pushrod makes sense especially with the combination of smaller base circle as well...it’s either that or I’ll just wipe all my lobes and bend all my valves when i crank it over the first time 🤦🏻♂️
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SLP IROC-Z (03-10-2020)
