Need some info/help

[cdwmotorsports]

I’m doing HotRod Dragweek this year in my Demon. We swapped heads and to Isky iron rockers and I’m trying to measure for new pushrods. The engine has a hydraulic .509 in it and I can’t seem to find the pre-load number for the lifters anywhere. Can someone please tell me what it is supposed to be?

 

[69FBCuda]

Do you have an adjustable push rod to check the baseline measurement?

 

[cdwmotorsports]

Do you have an adjustable push rod to check the baseline measurement?

I have an adjustable cup pushrod since the Iskys have a ball on them

 

[George Jets]

I’m doing HotRod Dragweek this year in my Demon. We swapped heads and to Isky iron rockers and I’m trying to measure for new pushrods. The engine has a hydraulic .509 in it and I can’t seem to find the pre-load number for the lifters anywhere. Can someone please tell me what it is supposed to be?

.030 ths

 

[cdwmotorsports]

.030 ths

Is there somewhere I can see this in a document? I’m not doubting you but I like to confirm things for myself

 

[George Jets]

Is there somewhere I can see this in a document? I’m not doubting you but I like to confirm things for myself

Like the way the Chevy 350 hydraulic cam settings. Bring the cylinder up on compression, then spin the pushrod with your fingers while tightening the nut down.

When the pushrod stops easily spinning > that is zero lash. Then you need to tighten down at the rocker 1/2 to 3/4 turn for the lifter preload. On chevs in the middle of the rocker. Adjustable roller rockers for the mopars are out on the end of the rocker.

(Say each 1/4 turn is .010 ths > that would be .030 ths preload at 3/4 turn.)

If you go light to start with at 1/2 turn and you get a little tick tick tick (on a restart) can go another quarter turn to add more preload and quiet it down.

Need to have some preload on the hydraulic lifters so they are not running topped out.


☆☆☆☆☆

 

[cdwmotorsports]

Thanks for the description that makes sense even though I haven’t had a Chevy for 32 years

 

[Bewy]

[1] If the lifters are new, they should not have oil in them. Push down on the plunger, & without oil in them, you will get 0.125 - 0.180" of plunger movement. That is the pre-load available & the lifters can be set anywhere in that range. Some people like to set the PL 0.020", or a small amount, but that risks lifter pump up & popping out a circlip if the engine is over-revved.
[2] Lifters have oil in them. Compress a lifter in the vise slowly to get rid of the oil. Then, perform [1]
[3] Brand new lifters made in the last 25 yrs. Say a prayer to Allah that your set will not fail, because plenty have.....Safest lifters are 25 yr old ones that have been re-faced.....