What preload is everyone running there morel 5206 lifters at? The morel spec for aluminum head and block is .045-.050. With my 7.40 pushrods I'm at .065-.070 preload. So if I order 7.375 I will be in that .045 range. I saw in another post a few years back people were running .060.

 

Bump .

 

I am running around .035" but some guys run up to .060" to keep the start up noise down. For me, I don't care about the noise if it performs the way it should.

 

I don't have the tie bar version but have run mine at 0.030" and 0.050". I am now running 0.050" because it is quieter and there were no differences in performance.

 

Thanks guys, I'll just stick with .045 then

 

The lifter has between .139 and .141" worth of travel. You want .040" of preload.

 

Thanks!

 

Hi Chris,
How many minutes of rocker bolt turn does 0.040" of preload can be translated?


Christian

 

1 turn = .047

 

Hi josh4ku,


May I ask you how you came with this number please?


Christian

 

1 full turn wtih a stock 8mm X 1.25 bolt is ~.047"

 

I understand this is the bolt motion but, does it translate in the same amount on the pushrod side?


Christian

 

1 turn torqued to 22lb/ft is real close to .047" It's very close

 

Ok so here is what someone posted on here that knows there stuff (Shane@TR)

__________________________________________________ __________________________________________________ ______________________
Originally Posted by XtraCajunSS
FWIW, EVERY cam install I have done using the LS7 lifter with a cam with greater than .600" lift (read smaller base circle) AND stock heads w/GM MLS gaskets has taken 7.425" pushrods for ~.050"-.060" preload. We measure lifter preload on each and every cam install we do. I have never had a lifter failure nor do we end up with the dreaded "sewing machine" noise.

Its very simple, If you change ANY of the following:
valve sizes, valve job, head milling, thinner/thicker head gaskets, decked block, cam with an altered base circle, etc... YOU MUST CHECK FOR PROPER PUSHROD LENGTH.

I have helped countless numbers of individuals with this process over the phone, via email, and PM's. I've posted the process on at least 3 occasions.

Here it is again in a nutshell:

1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.

For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...

I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.

If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.

 

You are going to use 5206 lifters and guess on the preload? That one turn for every .47 crap is a bad way of measuring for pushrods.

 

I have posted this before, but the 0.047" being measured is not the result of one turn of the bolt, rather ~2/3 turn of the bolt and the rocker ratio. Therefore, you can directly translate to different turns of the bolt.

 

Does it look like I used that method?

 

With your post #9,11,13 and 14 I assumed that you were going to use that method. Glad to see your not, no reason to get upset.

 

I have done it before on mild builds with ls7 lifters and usually ended up close to where I wanted to be. But I agree i would not do this for expensive lifters like morel!

 

Here is the starting post of a thread from another forum about LS1 engine using 1.7 ratio for the rockers...

The math is what it is, numbers calculation and results...

The interesting part is the control/test and the validation of the calculation

I am here quoting Treyelchivo:

"Originally Posted by treyelchivo...

Well after searching and searching for the RIGHT answer, I decided to check myself.
I did the math and figured that with one turn of the rocker bolt, you actually push the pushrod down .0778"
The pitch of the bolt is 1.25 mm which is .0492".
Assume total length of rocker is 2.7. (fulcrum to valve is 1.7 + 1 from fulcrum to pushrods) 2.7/1.7=1.588 X .049"=.0778".
So I checked it with a dial indicator today, came up with the same thing.

I read several posts about how many turns is desired and many people saying anything from 1 1/4 to 1 3/4 turns.
I also read that one turn pushes the pushrod down .047".

Well here's the real proof.

So if you are running 1.5 turns down from zero lash you have .116" preload.
I double checked and I had a little over 1.5 turns and .130" preload.
Do the math .130"/.078" = 1.666 turns.

So if you tell someone you are looking for .060" preload then say one and a half turns, you are giving bad info.
I say this because I can't count the threads where this is the accepted answer because of the bolt pitch without adding the multiplied movement at the end of the rocker.

Hope this helps some people and I'm sure there are people that don't agree.
Check it yourself.
I'm not a master machinist but have been one for about 7 years and have been reading indicators on coupling alignments for 17 years so I know how to read and setup indicators."

Christian