Pushrod Length Ordering

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thomasfouraker

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I mocked up a hydraulic lifter with some washers to make it solid to check for pushrod length. I am coming up with 6.800.

Now, I know that anywhere from 1/2 turn to 2 1/2 turns preload have been suggested through my research for the Magnum lifters.

My question is, whichever preload I choose, do I just add that much length to my 6.800?

Say I were to choose 2 turns preload (3/8 stud...... .042" per turn") I would shoot for a 6.900 pushrod?

1 turn would be 6.850 etc...

And just to avoid confusion with previous statements, I have 5/16x3/8 stud adapters to run 1.6 roller rockers so that's why my math is what it is.

Thanks and hope y'all have a great weekend!
 
read "pushrod geometry for engines" on utube, the one with the yellow rocker by straub industries & others there & checkout the hughes engines pics on valve stem contact. know the amt of preload you want.
 
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Torqueflite said:
The short answer is, no, you can't just add the preload to the pushrod length; there's geometry involved that won't let that plan work. To get your pushrod length, you should set valve lash at where you will normally run it, run the valve through a few full cycles with a solid lifter until you have a clear wear pattern on the valve stem tip (I use an erasable whiteboard marker on the tip since it wears off easily), and adjust the pushrod length and repeat the process until you see the desired wear pattern on the tip. For more detailed instructions, there are plenty of free tutorials online through valvetrain manufacturers and performance magazines.
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This crap might work on a Chevy stud mounted rocker system. You can take the push rod out and throw it across the room and the rocker to valve tip geometry won't change on a Mopar shaft system until you relocate the rocker shaft.
 
If you put the solid lifter in and set the adjuster to zero threads showing, wouldn't that get you pretty close as the exposed threads will then become preload? You can also see how far 2 1/2 turns drops the thread below the rocker. Two threads seems to be the golden number to shoot for.
 
IQ52 said:
This crap might work on a Chevy stud mounted rocker system. You can take the push rod out and throw it across the room and the rocker to valve tip geometry won't change on a Mopar shaft system until you relocate the rocker shaft.
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:lol: Yeah, my head is in Ford land. I helped my buddy on a 351W build last month and apparently need to get with it. Sorry. Deleted the irrelevant parts so as to not confuse the OP.
 
thomasfouraker said:
I mocked up a hydraulic lifter with some washers to make it solid to check for pushrod length. I am coming up with 6.800.

Now, I know that anywhere from 1/2 turn to 2 1/2 turns preload have been suggested through my research for the Magnum lifters.

My question is, whichever preload I choose, do I just add that much length to my 6.800?

Say I were to choose 2 turns preload (3/8 stud...... .042" per turn") I would shoot for a 6.900 pushrod?

1 turn would be 6.850 etc...

And just to avoid confusion with previous statements, I have 5/16x3/8 stud adapters to run 1.6 roller rockers so that's why my math is what it is.

Thanks and hope y'all have a great weekend!
Click to expand...
Seems mostly correct to me, but wouldn't it be 6.858" (One turn=.042")
 
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