wzup1000

iTrader: (17)

I would like to make sure that my process for finding lifter preload is correct.

I have aftermarket cam(~.600" lift), milled heads, milled deck, on a lq9 370...

using factory rockers, stock lq9 lifters, and 7.4 pushrods
with the dial indicator on the oil-hole on the pushrod side of the rocker (in-line with the pushrod),
tighten my rocker until zero lash,
zero out my dial indicator,
torque the rocker to 22ft/lbs,
wait a bit for lifter to depress (since filled with oil),
check preload.

after using this method (if correct) i have come up with ~.038-.039 intake, and ~.064-.065 exhaust.

any help is greatly appreciated
what is recommended lifter preload for a stock (ls1) lifter? how far off am I if my method of checking is correct?

02*C5

iTrader: (1)

First, make sure that the lifter that you will be testing is on the cam base circle. I like to just rotate the crank and watch the rocker. When the rocker comes off its lobe, you will see it. I give it a little crank more after it comes of the lobe to make certain it is completely on the base circle.

Next, take off the rocker arm. To check multiple pushrod lengths, you will need to get yourself a pushrod length checker. Start with stock length (7.400) and slide it into the pushrod hole:


Then put the rocker arm back on, but leave it nice and loose. You need to tighten the rocker down just to zero lash. So, grab the spring end of the rocker arm and wiggle it towards and away from the valve stem as you tighten down the rocker arm. Tighten the bolt until the rocker will no longer wiggle away from the valve stem, and no further!!!

Now, you need to set up your dial indicator. This is how I set mine up. Get it set on the lifter side of the rocker. Try to mimic the angle of the pushrod best you can. I had to offset mine a bit to get the socket in there. Zero out the dial indicator like in the picture.

Now, your baseline is zero lash, zero preload. Now torque your rocker arm bolt to 22 ft-lbs. You dial indicator will not respond immediately. Your lifter will now bleed off slowly. Just watch the dial indicator move. Eventually it will slow down and stop. This is your lifter preload!
In this picture, my lifter preload is .080". Right where I want it.

To verify an accurate measurement, untorque your rocker back to zero lash and verify that the indicator falls back to zero. If it doesn't, your indicator moved in the process, and you need to do it again.

Repeat these steps with different lengths on your adjustable pushrod to get what you want. I then mark the tops of the valve stems to verify proper rocker sweep. You want to get the best of both worlds here. Get a nice centered rocker sweep and preload within the acceptable boundaries and you are good to go. It may take a few sessions of trial and error with lengths, but you'll get it right eventually. I suggest .025" increments for length.

http://www.hardcorels1.com/vbulletin...read.php?t=622

All the info I put here was found on this thread with pics hope it helps you out.
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69LT1Bird

iTrader: (1)

Keep it even simpler, this works and even the guys on hardcore tried it and it passed their test.

Shane at Thunder Racing gets the credit.

"The TDC method is NOT always accurate. Try the EO/IC method to check pushrod length. I have posted directions on this forum numerous times... Here it is again:

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.

THIS METHOD ALWAYS WORKS!!!

Check it using the above method and see where you are."

Thanks,
Shane

vettenuts

iTrader: (4)

Your method appears correct to me. You may want to run this backwards as well, i.e., after tightening the rocker and the dial indicator settles, loosen the rocker slowly until the dial indicator stops. This should double check the numbers. From the looks of things you may need two different length pushrods.

The next key question is which pushrods? OD is king of the pushrod so you may want to consider a larger diameter for better valve train stability.

outkast6991

iTrader: (34)

what would cause the need for 2 different lengths? is it due to a poor VJ?

SOMbitch

iTrader: (8)

A different intake and exhaust lobe.....

69LT1Bird

iTrader: (1)

You wouldn't think the base circle would be off that much.

forcd ind

iTrader: (7)

i prefer doing the eo/ic, been doing that for 100 years, seems to be ok, lol
i kind of prefer using Veriner cal or whatever they call them, i finger tight untill resistance (you kind of get a feel) the bolt, then use the opposite end with the rod that comes out, meas tip of rocker (pushrod side) down to the head-then crank down till tight, and as said let it bleed down, then meas again
with a dial ind, its possible to have it move a little from the orig ck'ing spot, and throw off the reading-i am kind of suprised at the diff in meas you got,
but looks like your in the ballpark with the preload

Paul57

That's what I was thinking.

outkast6991

iTrader: (34)

i thought the base circle would be a constant regardless of the lobes used. thats why i thought the VJ might be the answer due to the tip height being off some. hmm

bearcatt

iTrader: (41)

outkast6991 ,

Some cams can be ground with two different lobe profiles, which have different base circles. thus requiring two different pushrod lengths to get even desired preload.

Comp Cam lobe profiles for example ... XFI, XE-R, LSK and XE.




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wzup1000

iTrader: (17)

thanks for all the responses. also, what is the correct preload for a stock lifter?
and i know the answer to this question anyway, but should i check every cylinder or is just 2 cylinders ok?

i forgot to mention that when i putting the heads together, I ended up using manley intake valves, and ferrea exhaust valves, putting me at different valve heights. I think due to the different brand valve heights, and having a valve job, and the tsp233/239 cam(.595 intake and .603" exhaust).

bearcatt

iTrader: (41)

If you checked two different cylinders, one on each side of the motor, you are most likely good to go.

The preload on your exhaust valves looks real good.

Since you will need two different length pushrods, why not try some Manton's ?


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wzup1000

iTrader: (17)

So, my dial indicator is crap, and is broken, and after the conclusion that it wasnt reproducing approximate (or even close) results, I decided to go with Shane's method.

I checked cylinders 1,2,3,4 to see if i could produce some approximate results but i seem to be getting some weird results(after double and triple checking all 4cylinders), which will make me check all cylinders now.

After making sure that the lifters were bled of oil (able to depress the lifter by using the pushrod by hand), and then checking,

My Results:

#1 INT:~1.00 turns=.0470" preload
EXH:~1.25 turns=.0645" preload
#2 INT:~1.50 turns=.0705" preload
EXH:~1.62 turns=.0792" preload
#3 INT:~1.25 turns=.0645" preload
EXH:~1.25 turns=.0645" preload
#4 INT:~1.00 turns=.0470" preload
EXH:~1.25 turns=.0645" preload

All were double and triple checked, all are close except for #2, which is why i am going to check them all.

What are your thoughts on this? What direction should I go now?

Get a new dial indicator to double check my results, or continue checking this way and order a bunch of mismatched pushrod lengths, or do I have other problems?

vettenuts

iTrader: (4)

Two thoughts here. First, get a new dial indicator or borrow one to check. Second, it could be that the valve job was bad and the valves are truly set at different depths. The only way to verify, in my opinion, with this number of issues is with a dial indicator as it appears you may have other problems that would render any method other then direct measurement problematic.

Bad Blu Formula

iTrader: (3)

Would you still need to use a dial indicator with the EO/IC method?

bearcatt

iTrader: (41)

What vettenuts said x 2


Also using this EO/IC method may work but in all honesty, on my own car I would much rather use a pushrod checker. Done correctly, it's easy, fast and accurate.

You're not doing a typical cam swap where 7.425 pushrods and the EO/IC method will usually work. Your motor deserves the utmost precision possible.

What's another $100 to buy a pushrod checker after spending hundreds or even thousands of dollars on an engine project.

This might help too. I saved this from another thread a while back, courtesy of vettenuts.




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vettenuts

iTrader: (4)

My only concern is you are not getting consistent results and since the heads have been worked that becomes a variable. If they were stock untouched heads I would say to review your methods, but your methods appear sound and your results are showing inconsistencies that may be the result of the head work. I would try and get a good indicator and figure out what is going on. If you don't want to spring for a dial indicator get an adjustable pushrod and check them. Less money and not as accurate but you should be able to figure out if the values you got using Shane's method are showing an issue with the heads. Also, make sure your lifters are against the cam each time you check a cylinder. As you rotate the motor they will tend to stay up unless you push them back down again.

A really quick and dirty check would be to put a straight edge over the tops of the valves and then use a feeler gauge to measure the gap. The straight edge should sit on the two highest valve stems. This may at least show you the heads are good/bad before going much further. Gaps are OK as long as consistent, i.e., all the intakes are the same height and all the exhaust have a gap of the same amount. If the numbers are all over then that would be another issue.

wzup1000

iTrader: (17)

wow, now i am stressed...so if my heads are total **** due to a crap valve job, then can i make up for that a custom set of pushrods? Even though they will be mis-matched, would that be bad assuming that the problem is corrected?

vettenuts

iTrader: (4)

I wouldn't panic but you need to figure out the source of the problem. Before spending a bunch of money, sort out why you are getting such different measurements.