Engine Pushrod Length Question

[germain101]

Just need a little sanity check. Changed out heads for a new set of aluminum ones with roller rockers. Put in a solid lifter and used my adjustable pushrod to get the tip centered on the top of the valve stem and then tightened the poly lock finger tight to take the slack out. Turned the engine over a few times and got a real nice mark dead center on the valve that is about .080" wide. Measured the push rod and it was 6.26" long.

What I'm concerned with is the pre load. I know some people tighten the poly lock 1/2 a turn when measuring the push rod length with a regular lifter and a checker spring, but I wouldn't imagine doing that with a solid lifter. I've also heard people say you need add .050" to your measurement when using a solid lifter to acount for the lifter preload. Where im getting hung up is, how much am I supposed to tighten the poly lock if I order a set of pushbrods that are .050" longer than my measurement? Or am I doing something wrong?

 

[AeroCoupe]

My understanding with a solid lifter in place on a cold engine is to adjust the pushrod for zero lash. Remove the pushrod and measure. That is your final length. Lash is set on a hot motor with your zero lash measured push rods. Warm the motor up and then adjust your rockers with the camshaft manufacturer’s hot lash spec. Rinse and repeat for each cylinder but make sure the motor is at or close to operating g temp.

 

[germain101]

Yeah, sorry for the confusion. I was just using the solid lifter to measure my pushrod length. I'm actually using hydraulic roller lifters to run the motor.

My problem is I'm not sure how much to add to the measured pushrod length and how much do I tighten the poly lock down after zero lash.

 

[AeroCoupe]

In this instance you go to zero lash and that’s it. Order the push rods, install new push rods, take to zero lash, then 1/4-1/2 turn past zero lash, and then set the poly lock.

 

[nicholase]

Yup. Just make sure the soild lifter is exactly the same measurement (inside of pushrod cup to roller tip) as the one your going to use. Probably pointing out the obvious.

 

[germain101]

Ok, so no need to add any additional length for lifter preload to my measured length? At zero lash (finger tight) and solid lifter for measurement, my pushrod length is 6.26".
I've got 3/8 studs which have 24 threads per inch. That gives me .042" per turn. If I give the poly locks 1/4 to 1/2 turn, that's about .011-.021" of preload on the hydraulic lifter. Just wanted to make sure I don't have to add anything extra to my measurement for preload. Thank you for the responses, its very much appreciated. Just want to make sure I get this right.

 

[nickyb]

Stop trying to add length to your rod.
It is what it is.

 

[Noobz347]

Stop trying to add length to your rod.
It is what it is.

I been doing it that way since ruler class in kindergarten.

 

[AeroCoupe]

Sounds like you need a stock length 6.25” push rod.

 

[germain101]

I think I just need to measure from underneath. I hear it's longer that way.

 

[nickyb]

No no no, balls don't count.

 

[General karthief]

Push rods have balls?

 

[Noobz347]

Rocker arms have balls.