push rod adjustment and heat.
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Road Master
Joined: Oct 2009
Posts: 1,132
Likes: 36
From: Las Vegas
push rod adjustment and heat.
Here is the set up: 2021 RG. Harley stage II with torque cam. New harley lifters and SE adjustable push rods. All adjusted by the book..TWICE! 
At the moment I am getting a top end noise that is deeper tone than ping, and not as deep as a knock. By knock I mean a type of noise you would hear if you "accidentally" lugged the engine.
This "noise" happens when the engine is hot and between 2000 and 2500 rpm in gears 1,2 and 3. AND while in Neutral.
I have read where some recommend putting an extra 1/2 to almost full turn on the push rod adjustment to make the rod just a bit longer, and that will help the noise go away. So instead of the factory adjustment to move the lifter spring half of .200 of inch, maybe adjust to .130 of an inch.
Given all of that, a part of me says, what a sec! Dont engine parts expand when hot? If that is so, then could the push rod expand a bit, along with the rocker arm, therefore affecting valve clearance and performance? So, if everything is "bigger" because of the heat, would it be reasonable to assume that when my engine is hot, the noise might be caused by the "hot" expanded parts causing the push rod to go deeper into the lifter? And if that is the case, would you want to adjust the push rod to a bit less than half of the .200 travel of lifter? Lets say adjust to .90 down instead of .100 down?
At the moment I am getting a top end noise that is deeper tone than ping, and not as deep as a knock. By knock I mean a type of noise you would hear if you "accidentally" lugged the engine.
This "noise" happens when the engine is hot and between 2000 and 2500 rpm in gears 1,2 and 3. AND while in Neutral.
I have read where some recommend putting an extra 1/2 to almost full turn on the push rod adjustment to make the rod just a bit longer, and that will help the noise go away. So instead of the factory adjustment to move the lifter spring half of .200 of inch, maybe adjust to .130 of an inch.
Given all of that, a part of me says, what a sec! Dont engine parts expand when hot? If that is so, then could the push rod expand a bit, along with the rocker arm, therefore affecting valve clearance and performance? So, if everything is "bigger" because of the heat, would it be reasonable to assume that when my engine is hot, the noise might be caused by the "hot" expanded parts causing the push rod to go deeper into the lifter? And if that is the case, would you want to adjust the push rod to a bit less than half of the .200 travel of lifter? Lets say adjust to .90 down instead of .100 down?
Seasoned HDF Member
Joined: Jun 2017
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From: Granville New York
First I'm not a professional but I do fix my own junk. Like you I've read setting the pushrods to get to .140 preload. Theory is the Motor expands when it gets hot. That Theory is true but some metals grow faster, some grow more and some do both. Your cases and heads are aluminum while the stuff you mentioned is steel of whatever alloy. Aluminum definitely grows faster, gets warm/ cool faster than steel does. That's why I think its widely recommended to set the lifters deeper than half of their travel. How many turns/ flats did you use? If you're around .100 another half turn might do the trick. Don't forget if you have an open air cleaner and put in an aftermarket cam you may hearing reversion from the cam itself.
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Road Master
Joined: Oct 2009
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From: Las Vegas
I appreciate the reply, but my brain is not clicking with something...Here is an Over-exaggeration of how I am thinking: If the engine gets hot, the push rod gets hot and expands. If it expands, that means not only circumference, but length. If I set the length of the push rod to compress the lifter spring half way when the engine is cold,(.100), then when the push rod gets hot, it will move deeper into the lifter, because its length is longer due to the heat. Next, I "speculate", that when my engine is hot, and the push rods are getting deeper into the lifter, the rpms of 2000, to 2500 are not quite high enough to force enough oil back into the lifter to compensate for the deeper push rod travel. But at speeds Over 2600, the deep tapping noise subsides because there is more "force" pushing the oil into the lifters.
So, in my mind, if I set the lifter pre-load to .090 instead of .100, that would compensate for the heat expansion of the push rod.
So, in my mind, if I set the lifter pre-load to .090 instead of .100, that would compensate for the heat expansion of the push rod.
Tourer
Joined: Jun 2021
Posts: 303
Likes: 146
From: Az
You might be over thinking this. If you think its the pushrod adjustment you can go another turn.
If in doubt you can always bottom lifter. You basically continue to go a turn, wait till lifter bleeds and pushrod can be spun easily, then and another turn, let bleed and can spin pushrod, repeat until no more adjustment. Dont force it and only one turn at a time Keep count from original amount of turns and you have your range. Its a lot more than people think. Limited travel lifters will be less of course.
You might be chasing rocker side play tic.
If in doubt you can always bottom lifter. You basically continue to go a turn, wait till lifter bleeds and pushrod can be spun easily, then and another turn, let bleed and can spin pushrod, repeat until no more adjustment. Dont force it and only one turn at a time Keep count from original amount of turns and you have your range. Its a lot more than people think. Limited travel lifters will be less of course.
You might be chasing rocker side play tic.
Seasoned HDF Member
Joined: Dec 2005
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From: poway
I appreciate the reply, but my brain is not clicking with something...Here is an Over-exaggeration of how I am thinking: If the engine gets hot, the push rod gets hot and expands. If it expands, that means not only circumference, but length. If I set the length of the push rod to compress the lifter spring half way when the engine is cold,(.100), then when the push rod gets hot, it will move deeper into the lifter, because its length is longer due to the heat. Next, I "speculate", that when my engine is hot, and the push rods are getting deeper into the lifter, the rpms of 2000, to 2500 are not quite high enough to force enough oil back into the lifter to compensate for the deeper push rod travel. But at speeds Over 2600, the deep tapping noise subsides because there is more "force" pushing the oil into the lifters.
So, in my mind, if I set the lifter pre-load to .090 instead of .100, that would compensate for the heat expansion of the push rod.
So, in my mind, if I set the lifter pre-load to .090 instead of .100, that would compensate for the heat expansion of the push rod.
Ask yourself what expands more, a pushrod which is made out of steel or aluminum cases, cylinders and heads.. Lookup coefficient of expansion for aluminum and steel.. Also which gets hotter, the cylinders and heads or the pushrod?
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From: poway
Because it can't collapse as far so it's easier to recover. Less oil in the upper chamber used. A little less fluid compression due to less fluid in the lower chamber.