how do you know if your push rods are to long?
Thread Starter
Staging Lane
Joined: Nov 2015
Posts: 82
Likes: 0
how do you know if your push rods are to long? how do you know if your push rods are to long?
started the motor for the first time, and i don't know if I'm being paranoid but i think I'm hearing a metallic sound from the motor. so this is what has prompted my question above.
running PRC Heads, Morel link lifters, Stock ls1 rocker arms, texas speed 228r cam, not sure about the push rod length.
im guessing either the rocker arms are making contact with the valve covers(no visible damage that i can see)
or
the valves are opening and making contact with pistons.
Car came with ms3 cam, and i swapped in the 228r, i didn't change the push rods..
so ls1 gurus, help out a noob, who wants to go fast-ish
started the motor for the first time, and i don't know if I'm being paranoid but i think I'm hearing a metallic sound from the motor. so this is what has prompted my question above.
running PRC Heads, Morel link lifters, Stock ls1 rocker arms, texas speed 228r cam, not sure about the push rod length.
im guessing either the rocker arms are making contact with the valve covers(no visible damage that i can see)
or
the valves are opening and making contact with pistons.
Car came with ms3 cam, and i swapped in the 228r, i didn't change the push rods..
so ls1 gurus, help out a noob, who wants to go fast-ish
If you brought the car to me, held a gun to my head, and demanded I determine if your pushrods are too long, this is what I'd do:
--remove valve covers
--rotate engine to make sure I'm in the base circle.
--use an adjustable pushrod and digital caliper to find zero lash.
--add preload based on the lifter choice
--compare measurements and calculations to existing pushrods. If my numbers are shorter than the pushrods, then the pushrods are too long.
IMO, only way to know for sure.
--remove valve covers
--rotate engine to make sure I'm in the base circle.
--use an adjustable pushrod and digital caliper to find zero lash.
--add preload based on the lifter choice
--compare measurements and calculations to existing pushrods. If my numbers are shorter than the pushrods, then the pushrods are too long.
IMO, only way to know for sure.
On The Tree
Joined: May 2011
Posts: 157
Likes: 2
He is saying take the O.A.L. measurements of the adjustable pushrod length @ zero lash, then add the desired preload to that number mathematically...not mechanically. So if your theoretical measurement is 7.350" @ zero lash and wanted to run .050" preload...the proper pushrod length is 7.400". Compare that to your existing pushrods that were installed to determine if they're too long.
What pushrods are in there? Morel lifters are taller and require a shorter pushrod. As stated above, better not run it anymore and take a measurement. If you think you tagged a piston, leakdown test is in order as well as you may have bent a valve.
"Too long" to me means hanging the valves open
"Too short" to me means there is lash
If your car is running fine, but you hear a metallic clacking, they could even be way too short.
Buy the $20 tool and measure, it's easy.
"Too short" to me means there is lash
If your car is running fine, but you hear a metallic clacking, they could even be way too short.
Buy the $20 tool and measure, it's easy.
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He is saying take the O.A.L. measurements of the adjustable pushrod length @ zero lash, then add the desired preload to that number mathematically...not mechanically. So if your theoretical measurement is 7.350" @ zero lash and wanted to run .050" preload...the proper pushrod length is 7.400". Compare that to your existing pushrods that were installed to determine if they're too long.
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Staging Lane
Joined: Nov 2015
Posts: 82
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These are the pushrods I'm running
TECH Fanatic
Joined: Jul 2007
Posts: 1,802
Likes: 332
From: Wilmington, De
Your pushrods are 7.300" in length.
You need to buy the pushrod checker and 8" calipers and find the proper pushrod length at zero lash. Then find the preload range suggested for your lifters and add that number to your zero lash number. That is the pushrod length you need for the engine.
You need to buy the pushrod checker and 8" calipers and find the proper pushrod length at zero lash. Then find the preload range suggested for your lifters and add that number to your zero lash number. That is the pushrod length you need for the engine.
I am running a 7.325 with a 61.5cc 243 head, .045 gasket, Morel 5315 lifter, and a 22x/22x cam. Pre-load is around .050.
You really need to measure and figure it out...every combo is a little different it seems.
You really need to measure and figure it out...every combo is a little different it seems.
Are the Morel 5315 lifters stock height? I know mine were taller as are the link bar lifters. That shortened the pushrod, however shimming the rockers lengthened it.
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
How much are your heads milled? I have prc 5.3 heads 59cc chambers, morel 5315 drop in lifters 222/226 cam motion cam and my pushrods are 7.350. When i had my 212/218 lunati cam with same setup my pushrods were 7.375. You will have to measure but i bet you will need longer pushrods. If you on the base circle of the cam and you find zero lash how many turns until the rocker is tight? That will give you an idea of your preload.
I thought they were a little taller. I did not measure just eyeballed it...my main concern was measuring off the base circle and adding the desired pre load. Did it several times and came up with 7.265 before pre load added if my memory serves me correct. That would be .060 preload not .050 with a 7.325 p.rod.
Last edited by kinglt-1; Feb 24, 2016 at 10:20 AM.
TECH Enthusiast
Joined: Jun 2005
Posts: 546
Likes: 0
From: Wichita, KS
If you brought the car to me, held a gun to my head, and demanded I determine if your pushrods are too long, this is what I'd do:
--remove valve covers
--rotate engine to make sure I'm in the base circle.
--use an adjustable pushrod and digital caliper to find zero lash.
--add preload based on the lifter choice
--compare measurements and calculations to existing pushrods. If my numbers are shorter than the pushrods, then the pushrods are too long.
IMO, only way to know for sure.
--remove valve covers
--rotate engine to make sure I'm in the base circle.
--use an adjustable pushrod and digital caliper to find zero lash.
--add preload based on the lifter choice
--compare measurements and calculations to existing pushrods. If my numbers are shorter than the pushrods, then the pushrods are too long.
IMO, only way to know for sure.
TECH Senior Member
Joined: Jun 2016
Posts: 22,293
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From: Central Cal.