Its the amount the pushrod depresses the lifter when the lifter is sitting on the cam base circle. Ir not on the ramp. As far as how much, that is determined by the lifter manufacturer. They arent all the same.

 

There is a plunger inside the lifter, it sits on a spring, it moves up and down say .500 (random number) from bottoming out to topped out with retainer clip on, is idea preload
half of that .500 movement

 

Found this video, I thought what he said about high RPM and high oil pressure is
very interesting, wonder how many times this happens and people blame the problem
on LS7 lifters

 

This video is always how I looked at hydraulic lifters also. To much preload allows a lot of error when the lifter pumps up. When I get on here and see .090 preload suggested I get alot of questions in my head as to how that could be a good thing.

 

Depends on the lifter being used. More thenikely what you read was related to LS7 lifters (which are commonly used) have somewhere around .160 travel in the plunger. So .080-.090 pre load is right in the middle of its range.

 

Well I double checked my push rod length today. These Manley's are exact length end to end as advertised. Since I have 1.85 rockers, I used 2.7/1.85 = 1.46. .049 x 1.46 = .072 rounded for 1 full turn. I did the bolt turn method 6 times and came up with 5/8 of a turn 4 times and 3/4 of a turn 2 times. So it appears my pre load is in the .048 range averaged. This is with the engine hot fwiw.

 

You should be about perfect

 

Yep I think so...now I am convinced the noise is a biproduct of Hydraulic valve trains with stock style rockers, higher spring rates, combined with more aggressive lobes.

 

It could be. It's known to do that. My valve train actually got quieter when I jumped to solids.

I did also find that switching to castrol
Edge quieted the motor down when it was still hydraulic

 

Are you running YT rockers?

Yes I believe Kip mentioned his LLSR setups being much quieter then most hydraulics. My brother just ordered a custom LLSR from Kip last week for his 383 LT1. Going from a Hydraulic 230/236 114 to a 244/256 110+4 LLSR.

 

yes I am. You just have to make sure the intake and exhaust base circles are the same. When you use shaft mounted, non adjustable rockers.

That'll be a big upgrade. Should act like a 238/250, but it'll rev like you can't believe.

 

Ahh...so you ended up with different push rod lengths for the intake and exhaust?

 

I ended up with different pushrod lengths for each Valve.

I literally measure each one and the. Measure the ones I have available and use the closest fit. Then I use shims to correct from there. The main thing is to make sure the pairs are level. So if I need a 010 shim, I make sure I need that same shim for both sides. You can preload the valve up to 003. So I did end up with the occasional intake valve preloaded 003 and exhaust preloaded 001 to keep the trunions level.

 

The bolt turn method is great at being consistently wrong, since it doesn't account for bolt and head thread stretch. The last 1/2-1 turn, the trunion of the rocker (and thus the rocker tip) isn't moving, as it's fully seated in the cup - which means all of your measurements and assumptions are wrong.


YRMV.

 

I used the bolt turn method that does not include tq'ing bolt to 22ft lbs to verify my initial measurement I took with a push rod checker using the EOIC method. It ended up being right on par. Aside from that, I did the bolt turn method 6 times and results were within .010 each time. If there is a better way then please share?

 

treed. I don't use rotations to do anything but double check my initial measurements. And when I do, I use dead soft touch and no torque, because at that point additional rotation is strain, not preload.

 

Yep...the only reason why I brought this up in this thread is because I have 5315 lifters and I thought this info might be useful if somebody stumbles across it via a google search.

So just to clarify what I did.

-1.5yrs ago when finishing my build, I used the EOIC method to find my correct push rod length.

-I came up with 7.265 using a push rod checker. I then added .060 to that number for my lifter pre load with a cold engine...that gave me a total length of 7.325

-I purchased a set of 7.325 Manley push rods and installed them. Car runs great, pulls clear out to 7k plus like lightning.


Fast forward to this thread and it got me thinking that possibly my push rods were a tad short because I do get some sewing machine noise once the oil gets up to temp. You can talk to 10 different folks knowledgeable about LS motors and it's a 50/50 split on being normal or incorrect push rod length.

So I decided to double check my initial measurements with the Bolt turn method DarthV8 uses that does not include tq'ing to 22lft lbs. This method proved that I am within .010 of my initial measurements which should be sufficient for this build. If I was running a LLSR and Shaft rockers, then yes I would want to be within .003 across each valve and I would of went even further in depth.

This was more for piece of mind because I am pretty **** about things being right no matter what it is.

 

There is a lot of grumbling about "sewing machine noise" in general. It has literally 0 to do with a properly setup valvetrain. The measurement of the checker is the right thing to do. Some choose the bolt-turn method. I've already stated why I feel that is wrong, because it will always generate an inaccurate measurement (even if its repeatably inaccurate).

Mine's pretty chattery cold, but it quiets down once oil is up to temp. A big bit of the lifter preload target depends on your target application. Someone who spends a long sustained time at rpm/WOT (should) will need to run less preload, because the valvetrain will be far more stable. In a 1/4 mile car, or grandpa's sunday driver, more preload may quiet down the valvetrain and make him happy. Doesn't mean it's optimal.

 

Wow wish this much info was in one thread (that I could find) when i was initially trying to install these. Redid my preload with the soft touch method and they came out at the original 7.4 engine runs a lot better and quieter now. The original reason for the thread was because the morels are slightly different in height and I thought I would need a different length pushrod. So for the next person wondering they end up taking the exact same length as stock since they like less preload. That was the info I kept searching for but couldn't find

 

If you want to get within that .005" range you really should measure them all especially if there has been any valve work done. You'll find they are not all the same.