I have .040"-.050" preload with 7.375" pushrods. I'm running Hylift-Johnson 2148SE lifters. They call for .020"-.040" preload. If I drop a size, I'll only have .015"-.020" preload. Would you agree that I should run the 7.375"s that I have?

 

According to their description of the lifter you'll want to run less preload.
.010 over what they suggest may not be an issue. Do you drive it like you stole it or are you easier on it?

"The only draw back of this type of lifter is that if the valve train should “Float” because of reaching a higher RPM than the valve springs can handle these lifters will try to take up the excessive clearance causing the valve to hang open resulting in a loss of power. "

 

The next size shorted PR will drop my preload to only .015"-.025" though. That doesn't seem like enough.

This car will be used but not abused. I will be setting my rev limited no higher than 6800. I plan to shift around 6500.

 

Hi I was a little concerned that I would encounter the same issue with my 2148 SE lifters so I asked Hylift about it this was the reply below in blue.

​​​​​​On this subject previously when I ran my stock LS1 lifters with a BTR 219/224 .551 lift cam I didn't check my preload and noticed on disassembly it took five to six turns of rocker to take up preload and this below in pic was the result after running it for about 7000 miles. There was no ticking or sign that anything was wrong.

The cam was sold to me as one that could use stock pushrods, the motor was stock. After this I'd rather have too little preload than too much and just check it more often. Although this was on a stock lifter.

I was just lucky the cam was still in perfect condition and the lifters didn't self destruct.

QUOTE:
We just recommend getting as close to .030 as possible. Yes, guys set their tolerances in all different settings.
To achieve the lifters best performance we recommend .020 - .040 .
Thanks & good luck with your rebuild.
Dave Ewert
Hy-Lift Johnson Lifter Co.

 

How are you measuring preload?

"next size shorter OFF THE SHELF pushrod"......
You can have pushrods made in any length you want.

 

Call manton or Manley and order the exact size you need. They will make it accurate to within .003 of whatever you want.

There are times I have ordered 7 at length A, 4 at length B, 3 at length C, 1 at length D, and 1 at length E. They are used to it.

 

I'm just a novice with this but would it be possible to shim under the rocker pedestals to get the desired preload and run the pushrods he has?

 

if you shim the rocker youll effect swipe on the valve stem

 

This.
shiming/milling the pedestals will affect rocker geometry, while altering pushrod length. That’s a whole different can of worms.

 

https://www.google.com/url?q=https:/...zbsBQaE25FHFsw

Here's a thread about shimming instead of using adjustable rockers on a solid lifter setup.

 

I think the quote in bold answers my question. I think I should be fine. I would still like to talk to them directly though. I really think 7.350" would be too short. The only other solution would be to do as Dart said and order exactly length PRs.

 

With an adjustable PR checker.

 

Run the 7.375. I called johnson for my 2110s and i had a similar situation as you. They said more preload is better than less. Also - per their instructions, you want to average the lengths measured for intake and exhaust on 1 head, and do the same on the other head. So you'll have 4 pushrod lengths. 2 exhaust, and 2 intake. Call johnson if you are unsure, but they told me dont overcomplicate it, and a little over on the pre-load is better than under.

 

As time goes on, preload will do nothing except DECREASE. Parts WEAR, they don't GROW. Plus, aluminum (castings) GROWS more than steel (push rods) due to heat; that .040" cold will likely turn into about .032" hot.

Therefore, if you start out with slightly too much (emphasis on SLIGHTLY) when new, at some point in the not-far-distant future, it will most likely adjust itself on its own due to natural consequences, right into the "optimum" range. Whereas, if you start it with it on the very lower edge of "acceptable", it will soon fall out of that range, and into NO preload, which is definitely an adverse outcome.

I think you might have gone down the rabbit hole of "measure with micrometer, mark with chalk, cut with torch".

I'd say, run it at 7.375".

Shimming, in the amounts under discussion (.015" or the like), will have no material effect on rocker geometry. It would take something in the .100"s to throw it off enough to matter. Just the same, I wouldn't bother, in this case.

 

I have used shims like that. But I also run lash caps to spread the load and scraping across a bigger surface.

So figure a machine shim kit, and the cost of lash caps, and the cost of pushrods. Cheaper and simpler to order the custom pushrods imo.

If you are running solids, I would tell you to get the custom rods, the shim kit, and the lash caps. Then it is golden and stable.

 

I like what I'm hearing. It makes sense.

 

I posted the shimming out of curiosity. I'm trying to learn.
Given the info posted I would conclude the best course of action is to follow the recommendations to run the pushrods you have. One thing that hasn't been mentioned is the effect of the temperature on the amount of preload. On the solid setup it seemed accepted that .010 in lash would be created when at operating temperature. I'm thinking that would equate to less preload with hydraulics provided it is an aluminum block.

 

I've used the Comp tool with an 8" caliper. Between counting turns on the tool and measuring it with a caliper there's enough error that might put you at the desired length.

An example is not turning it full turns, did you need a 1/4 turn on the pr checker? I needed 1/8 turn. One might think it's easy, just divide one turn (.050) by 8 and put that into the measurement. In this case it's much easier to use a caliper.

 

That's probably fair: I was giving it .008", just for aluminum heads, since he seems to be talking about a LQ4. The exact value would depend on operating temp, which in turn (independent of cooling system settings) would depend on engine load. A street motor might have a lower #, an oval-track motor higher, for any given coolant temp. And you're right, the thermal expansion of the castings would take preload OUT. That's the way we've all dealt with solid lifters over the years.

However all the minor details might be, I think he's got a perfectly usable situation, ready to tighten the rockers down (with some thread sealer on the bolt threads) and put the valve covers on.

 

Yes an aluminum block you would see preload decrease but .010. On an iron block figure it will stay the same.