We have tested 5/16 .105" wall pushrods with great results. We've engine dyno tested the .105" vs .080" wall with good results. The down side is the .105" wall pushrods are considerably higher in price, but if someone wants them we stock them!!

Preload is definitely important & different lifters seem to like different preload from the testing we've done. I guess that's one of the great thing about having a engine dyno to test all these things in the search of power.

 

Hi Matt

Any results for pre loading the LS7 lifter as to what works best? Regarding the pushrods I would like to see a test that also involves the 3/8" pushrods. You can get them in .065", .080" and thicker of course.

Maybe we can get a fund going for the tests.

 

Something that keeps bothering me is trying to understand what portion of the various lifters goes unstable or breaks. I know you will eventually hit an RPM where the lifter can no longer refill at pressure, but this would just be an upper RPM limit. As I understand it, the basic premise of a hydraulic lifter is that you can use intermintent oil pressure to constantly adjust the height of the pushrod cup, always eliminating any lash. To do this, you have a checkball and spring, inner body, outer body, retainer clip, and some metered oil orifices as well as a metered plate to allow some oil to go upstairs through the pushrod. When the valve is closed and the lifter is on the base circle, the oil pressure pushes up on the inner body (may have a better name) and ensures that the pushrod is against the rocker and the rocker is against the valve stem. When the lifter returns to the base circle, it refills with oil pressure and ensures there is no clearance. Not certain that I am saying this correctly. There really is no reason that I can envision for worrying about a short pre-load, as the only way it can get shorter is for the valvetrain to shrink (get colder). Even if that did happen with a winter cold start, wouldn't it just act like a mechanical once the cup was against the retainer spring? As the engine warmed up, the oil pressure would keep it at zero lash until everything got so long it bottomed out. That is a tremendous distance, and not feasible, so it would seem that using whatever pushrod length (or adjustment if you have adjustable rockers) gives you quiet operation and good valvetrain stability would be fine.

Hmm, looks like I forgot to account for the block and head expanding which would make the system seem shorter. I wonder by how much?

 

With an aluminum block and heads, going from cold to hot is going to eat a lot of this preload. Aren't you concerned with running the plunger that close to the clip? A few guys have lost motors due to clip failure.

 

That is the kind of question we are trying to answer! Had not considered the block and the head growing with heat, only the valvetrain. How much will it grow? I know that pushord will get longer, and the valve stem will get longer, how much will the rest of the combination change over temp? The 15 mils was recomended by a local engine builder, and did really quiet the noise. Is there a minimum pre-load we should be dealing with? No-one seems to have any absolute answers! Also, will the clip fail if the cup is against them? Would hate to have to buy another damn set of pushrods.

It would be interesting to spend a Saturday swapping in the lengths between 7.3 and 7.4 to see when the noise starts. I would just need 7.325, 7.350 and 7.375... hmmmmm, it would be interesting, but for another $350, I am not sure I want to do that....

 

Diameter has more to do with the strength of the pushrod than the thickness. Unless maybe you use a solid pushrod.

 

True, the last engine dyno I worked with I was able to squeeze in 7.800" | 3/8" instead of the off-the-shelf 5/16"; I was content with the results. When I get time and am on the dyno again, I'll try to test an unstable valvetrain, which might just be a pushrod swap away...

I have used some thicker walled 5/16" that worked where a larger dia wouldn't fit without machining. Larger dia would have been preferred, but did not have the time/option to remove the heads.

 

Cool, I'd love to see the results.

 

"Diameter has more to do with the strength of the pushrod than the thickness. Unless maybe you use a solid pushrod."

No argument from me.

 

I have seen various numbers, not sure anyone knows exactly but 0.015" of growth has been mentioned by a couple of people I know who have a lot of LS1 experience. Also, I have recently been corresponding with Morel on their preload requirements and the difference between recommended preloads in going from iron block/aluminum head to aluminum block/aluminum head is 0.014" to allow for growth. If you eat it all up and the lifters pump up you may push the clip out of the top. Guess I would be concerned running stock lifters with that light of a preload, but I am not by any means an expert either.

 

And continuing the saga:

http://www.hardcorels1.com/vbulletin...6&postcount=40

Is that proof yet, maybe not but it sure makes me wonder.....

That was posted on an illustrious thread from where The alchemist, eskimo, Jessica and Co. get all their info. Ammazing that all ignored him like he did not even post

 

Too bad you don't post the rest of that thread...

or even this http://www.hardcorels1.com/vbulletin...&postcount=100

Waaa, waaa, waaaa In my best Debbie Downer tone.

 

What, the part where he says that he will play on his dyno and change different pre-load values to verify?

Or the part where you tell him that he might be making an error because even YOU have a difficult time adjusting 0 lash on those rockers?

As for that thread above, even paper calculations would show that those pushrods (7.400) were too long and that HE CHOSE to run 7.300 but 7.350s would have worked as well with more preload.

Your word on preload (on LS1/LS6 OEM lifters) choice is not gospel, you prefer light (.020 as per your post) and I prefer .080 range as per my experiences. (So does Katech and Lord knows do they know their stuff about LS motors)

 

So much so that they have wanted to use rocker arm systems that us little old know nothing Hillbillies design and make.

I don't care that you like to use that preload... you do so many other things wrong it's not like that few HP you give up is the only thing your missing.

Doesn't the sun shine in Dubai all the time??? It does here so I'll let you have the last word at this for now.

Bret

 

I don't care about either ego or argument, I just want to know will anything bad happen using the 15 mil preload? NO ONE ON ANY FORUM is answering that particular question. Several local guys have said everything is cool, including my tuner, but I wouldn't mind some verification from some sources that have a few more miles and engine builds under their belt.

 

Question on another site:

http://www.hardcorels1.com/vbulletin...56&postcount=1

Isn't this one of your posts? Your reply as a matter of fact!

http://www.hardcorels1.com/vbulletin...74&postcount=2


Or is your theory on LS1 lifter preload and what is best, based on extensive testing as you always dish out.

(Bottom 3 lines of this thread on post #120)

https://ls1tech.com/forums/11479226-post120.html

I think not

A pic is worth a thousand words, explain that to your pac and say hello to Jessica for me.

 

 

SO, you going to answer my question or not? What will happen with the 15 mil pre-load?

 

I wouldn't, I would add another .050 and run 7.350

 

What about 7.325 if running 5.3 heads with 62 cc chambers?