Pushrod Length Measurements...Experts Come On In
Thread Starter
Joined: Mar 2011
Posts: 2,688
Likes: 19
From: Stratford, CT
Pushrod Length Measurements...Experts Come On In Hey guys, need help verifying my pushrod length for my build. Valvetrain setup is a custom grind cam motion cam, tea heads, stock thickness head gasket, morel 5315 lifters, and stock rockers w/ straub trunions. This is my first time measuring for pushrod length and wanted to make sure it was done correct.
My method of getting the measurements was to set the adjustable pushrod checker to the appropriate length and tighten down the rocker so there was 0 lash. I only had the pushrod checker seated in the lifter cup and did not depress the lifter, so preload is not yet accounted for.
From what I have read, Morel 5315's are typically run at about .040 preload, so I added that in after getting my total average length.
If what I did was not the correct way, feel free to share and I can go back and double check easily (motor is on a stand).
Below are my measurements:
cyl 1 - Intake: 7.347 / Exhaust: 7.350
cyl 3 - Intake: 7.348 / Exhaust: 7.348
cyl 5 - Intake: 7.345 / Exhaust: 7.345
cyl 7 - Intake: 7.345 / Exhaust: 7.345
Average length: 7.346
cyl 2 - Intake: 7.362 / Exhaust: 7.355
cyl 4 - Intake: 7.354 / Exhaust: 7.345
cyl 6 - Intake: 7.353 / Exhaust: 7.353
cyl 8 - Intake: 7.360 / Exhaust: 7.350
Average length: 7.353
Combined average length: 7.349 + .040 lifter preload = 7.389" for pushrods
My method of getting the measurements was to set the adjustable pushrod checker to the appropriate length and tighten down the rocker so there was 0 lash. I only had the pushrod checker seated in the lifter cup and did not depress the lifter, so preload is not yet accounted for.
From what I have read, Morel 5315's are typically run at about .040 preload, so I added that in after getting my total average length.
If what I did was not the correct way, feel free to share and I can go back and double check easily (motor is on a stand).
Below are my measurements:
cyl 1 - Intake: 7.347 / Exhaust: 7.350
cyl 3 - Intake: 7.348 / Exhaust: 7.348
cyl 5 - Intake: 7.345 / Exhaust: 7.345
cyl 7 - Intake: 7.345 / Exhaust: 7.345
Average length: 7.346
cyl 2 - Intake: 7.362 / Exhaust: 7.355
cyl 4 - Intake: 7.354 / Exhaust: 7.345
cyl 6 - Intake: 7.353 / Exhaust: 7.353
cyl 8 - Intake: 7.360 / Exhaust: 7.350
Average length: 7.353
Combined average length: 7.349 + .040 lifter preload = 7.389" for pushrods
My method of getting the measurements was to set the adjustable pushrod checker to the appropriate length and tighten down the rocker so there was 0 lash. I only had the pushrod checker seated in the lifter cup and did not depress the lifter, so preload is not yet accounted for.
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
By your numbers i guess you measured with a caliper. As long as you didn't push the plunger in you are good. You need to subtract .017 if you measured with a caliper. The measurement with caliper is a little longer than the pushrod advertised length. So i would say the pushrod you want is 7.375.
Thread Starter
Joined: Mar 2011
Posts: 2,688
Likes: 19
From: Stratford, CT
By your numbers i guess you measured with a caliper. As long as you didn't push the plunger in you are good. You need to subtract .017 if you measured with a caliper. The measurement with caliper is a little longer than the pushrod advertised length. So i would say the pushrod you want is 7.375.
I did mine differently so I just want to make sure I follow what you’re doing. Sounds like you tightened the rocker enough so it’s fully seated with the stand. Then I assume you adjusted the adjustable pushrod until it made contact/had friction with the back of the rocker arm and then tightened the rocker bolt until you got zero lash?
I run those Morels at .065-.070” preload which is half of their full travel of .140” despite Morel recommending less. I was aiming for .060” as that’s what Tick has recommended in previous posts but my 7.400 pushrods put me a touch beyond that. Nothing wrong with .040” but just to note if a particular length pushrod increases your preload a tad beyond .040” it won’t be an issue for ya.
I run those Morels at .065-.070” preload which is half of their full travel of .140” despite Morel recommending less. I was aiming for .060” as that’s what Tick has recommended in previous posts but my 7.400 pushrods put me a touch beyond that. Nothing wrong with .040” but just to note if a particular length pushrod increases your preload a tad beyond .040” it won’t be an issue for ya.
Last edited by StealthFormula; Nov 15, 2017 at 10:00 AM.
Thread Starter
Joined: Mar 2011
Posts: 2,688
Likes: 19
From: Stratford, CT
I did mine differently so I just want to make sure I follow what you’re doing. Sounds like you tightened the rocker enough so it’s fully seated with the stand. Then I assume you adjusted the adjustable pushrod until it made contact/had friction with the back of the rocker arm and then tightened the rocker bolt until you got zero lash?
I run those Morels at .065-.070” preload which is half of their full travel of .140” despite Morel recommending less. I was aiming for .060” as that’s what Tick has recommended in previous posts but my 7.400 pushrods put me a touch beyond that. Nothing wrong with .040” but just to note if a particular length pushrod increases your preload a tad beyond .040” it won’t be an issue for ya.
I run those Morels at .065-.070” preload which is half of their full travel of .140” despite Morel recommending less. I was aiming for .060” as that’s what Tick has recommended in previous posts but my 7.400 pushrods put me a touch beyond that. Nothing wrong with .040” but just to note if a particular length pushrod increases your preload a tad beyond .040” it won’t be an issue for ya.
I'll order the 7.375" pushrods and run it.
^Just realized that .040" preload may be a bit light for the 5315s, the paperwork states .045"-.050" for an aluminum block and heads assuming that's what you have. As I mentioned before, Tick recommends .060" and it appears many other folks run ~.060" preload as well so I'd personally aim for a bit more than .040". I'm thinking a 7.400" pushrod (measured in caliper length) would be about right (so that would be a gauge length of ~7.383" give or take) which would result in ~.050" preload.
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Thread Starter
Joined: Mar 2011
Posts: 2,688
Likes: 19
From: Stratford, CT
^Just realized that .040" preload may be a bit light for the 5315s, the paperwork states .045"-.050" for an aluminum block and heads assuming that's what you have. As I mentioned before, Tick recommends .060" and it appears many other folks run ~.060" preload as well so I'd personally aim for a bit more than .040". I'm thinking a 7.400" pushrod (measured in caliper length) would be about right (so that would be a gauge length of ~7.383" give or take) which would result in ~.050" preload.
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Verdad Gallardo TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
heads will grow .006 to .008" when the engine is warm. This reduces preload. On an aluminum headed engine/iron block Morel wants around .045" of pre-load. This is what Morel told me through email. I am more in the .040 range and my valvetrain is dead quiet. When i had longer pushrods in with a preload around .070 it had some noise. The morel definitely like less preload then more.