Peload

[optmaxx]

I've posted videos of my stroker running because the valve train was a little noisy, and I was a little concerned. So, I was told how to check my preload by measuring between the rocker arm pivot and block, and the numbers don't seem too far off I think. The method I used was to finger tighten the rocker bolts till I couldn't spin the rod with my finger before measuring, and going by the firing order. I watched the distributor's rotor to make sure I was in the correct firing order, it made easier and I hope that was the correct way to do it. One of rocker bolts on cylinder 4 took a little more finger tightening to keep the rod from spinning, but the measurement wasn't crazy off. I actually just found out that I only had to finger tighten till the rockers had no play, but the rods can still spin, so it could be that my measurements could be just a little more? It didn't really take much to make the rods stop spinning though. Lee from Hesco that it should be around .060 > .080, but I just want to post my finds and see what you guys think.

#1 Intake .070, Ex .065

#5 Both .060

#3 Both .065

#6 Both .060

#2 Both .060

#4 Intake .040, Ex .060

The only thing that got milled was the head, and I called the place I bought it from and they said that they mill their heads the minimum of .006 to .010, and I have the VR head gasket, stock 1996 cam, stock 4.0 push rods and stock rebuilt 7120 head. If I should have to shim the pivot, can I find some washers at home depot to test it? I also have the rocker bolts torqued to 21 ft lbs, is it a good idea to give the bolts another small turn to see if that helps?

[Russ Pottenger]

Setting lifter preload is critical in any hydraulic lifter engine.
Because our 4.0 Jeep engines are non adjustable. It creates other challenges unless we go with a after market rocker arm.

When your engine machinist is doing the valve job it's essential that the valve tips are set correctly and consistent with
one another. When building are stroker combinations, we in most cases are shooting for something around a zero deck.
To achieve that it's not uncommon to remove .040 from the block and .020 off a ported head. Toss in another variable
of a different length valve and you can see that a stock length push rod in many cases will no longer work.

Most of the lifters I run into usually have approximately 3 full turns of plunger travel. When the lifter is on the heel
on the cam lobe (no lift) you would like the adjustment within the first half of that. With a few exceptions, 1/4 to 3/4 turns would be ideal.
After visualizing I have clear hole through the center of the push rod, I'll put assembly lube on both ends of the push rod and on the valve tip. With both intake and exhaust lifters on the heel of the cam install the push rods in that cylinder.
I use a socket on a T handle to adjust the rocker bolt. As I'm tightening the bolt I'm twisting the push rod with my finger tips until I feel some resistance. I use a T handle rather than a ratchet because it allows more sensitivity in judging when the plunger is starting to depress.

I use Chevy LS valves in all my strokers and usually end up using a 9.550 to 9.600 push rod.
Your tips aren't too far off from one to another. So you should be fine with a single length push rod.


Russ