Hydraulic lifter pre-load

[RBCharger]

Finally got the TF 270 heads on, the hughes 1.6 rockers on, and the pushrods in. Cam is comp hydraulic flat .545 241/247 (.581 with the 1.6 rockers) and comp lifters. Comp calling for .045 lifter preload. Seems like an awful lot of preload. Thinking the trick is to keep the inner plunger off of the retaining clip and .045 will likely kill the top end. Was shooting for .030 preload with pushrods I installed. Mybe .015 difference isn't worth worrying about? Regardless, at .030 preload I've got 1 thread of the adjuster on the rocker below the bottom. Looks perfect. From memory I think the rocker adjustors are .055 per turn (need to double check).

Any thoughts on the lifter preload for hydraulic flat?

 

[pnora]

Most rockers are 3/8 fine thread so one turn will get you the .040 preload. It will not hurt the top end or any other RPM range.

 

[Master Gunner]

Well, Hughes lists the standard preload at .080-.095", so .045" is really not that much. I don't think I'd worry to much about .015" in this case and go with what the Mfg recommends.

Mark

 

[beanhead]

If the instructions call for .045, that's where you should set them. In the past when I used Comp's standard (not pro-magnum) hydraulic lifters they wanted .020-.060, I always shot for the middle and set them at .040, no problems.

 

[Geoff 2]

The vast majority of hyd lifters have a range of 0-0.150" of pre-load adjustment [PL], some have more, like 0.180".

The only reason to set the PL tight is in case the lifters pump up at high rpms, the valve will only be held off the seat by a small amount & minimal power will be lost.
The risk with this procedure is the circlip failing to hold the lifter together......
The risk is greater with alum heads because the PL clearance gets used up quicker because of the higher expansion rate of alum. True Anti Pump up lifters have stronger circlips but these can fail..& do.

It is better to set the PL around the middle of the travel to allow for a healthy safety margin & there is no loss in performance doing this.

 

[RBCharger]

Most rockers are 3/8 fine thread so one turn will get you the .040 preload. It will not hurt the top end or any other RPM range.

That's helpful - I actually don't see a number on the Hughes information. I'm going to re adjust to 1 full turn + a scoche.

 

[INTMD8]

The vast majority of hyd lifters have a range of 0-0.150" of pre-load adjustment [PL], some have more, like 0.180".

The only reason to set the PL tight is in case the lifters pump up at high rpms, the valve will only be held off the seat by a small amount & minimal power will be lost.
The risk with this procedure is the circlip failing to hold the lifter together......
The risk is greater with alum heads because the PL clearance gets used up quicker because of the higher expansion rate of alum. True Anti Pump up lifters have stronger circlips but these can fail..& do.

It is better to set the PL around the middle of the travel to allow for a healthy safety margin & there is no loss in performance doing this.

Agreed and would like to add that it's better to get the valvetrain under control instead of needing/relying on lifters that won't blow apart during a loss of control.

 

[Geoff 2]

^^^^^^

Agree 100%.