So I'm driving and hear a very loud knocking sound which turned out to be a bad lifter in my GTO. We replaced all lifters with LS7 lifters, installed a new cam since we were in there and the car started just fine and has been doing very well since then. About three weeks ago I heard the cam making a bit more noise as it spun hitting the lifters especially what sounds like one lifter in particular which went away shortly after. Two weeks ago it started making the noise again and it was getting close to oil change time and because I live in the desert I swapped my oil to some Mobil 1 0w/40 which quieted it down a tiny bit.

Now it for the most part is quite at first start up and then starts to tick after it's been running for 2-3 minutes and I guess my question is, is this normal for the LS7 lifters after they have had a little bit of mileage on them or is there something else that might be happening? Do these lifters get louder as they wear in?

My GTO has an LG cam, with dual valve springs as well as an SLP oil pump, so it should be getting all the oil that it needs.

I don't know if I'm worrying about nothing or if there is anything I should be looking for or checking?

 

Preload measurement?

 

I didn't take a measurement as I talked to LG before I installed the cam and they told me to use the 7.4 pushrods with the lifters.

 

Dependent of the base circle on the cam you could still be looking at .025" too much preload easily if not more. I have to run a 7.375" PR to run the LS7 lifters and stay under .100" preload. The extra could be causing the lifters to fail. You should ALWAYS measure when you change anything in the valve train geometry.

 

x10,000.

The cup onthe re-designed lifter is shallower AND the lifter specs ask for less preload.

I had to change to a shorter pushrod after my LS7 lifter swap myself.
Been running two year and 10,000 miles on these for far - no complaints yet.

 

I really appreciate the information and thought I was safe after talking to LG about it. Is there a write up on how to measure as I have never done this before and want to make sure it's done right.

 

I use this method.

Make sure you're on the base circle of the cam. Torque the rocker to 22ftlb with the pushrod checker in the hole but not touching the rocker. Then turn the adjustable pushrod until your at zero lash. Remove the rocker, remove the pushrod and measure it with a dial caliper. Then add the amount of preload you wish to run to that measurement.

 

Never listen to what ANYONE tells you. They only say what the usual recommendation is, they don't have your car in their hands to know what size you need. Texas speed also told me 7.4 for my cam, yet I think I had to go a little shorter. You should ALWAYS measure for pushrods.

 

Great information and thank you, and will do as advised and never trust anyone like that again as I felt I was in good hands talking to a reputable manufacturer. Is there a place to find the preload I would need?

 

Whats the best way to get your measurement? I have a dial indicator that has 1 inch of travel and dial calipers that have 6 inches of travel....

 

What? Get a bigger caliper.

 

If you have a caliper that only measure 6 inches, which lots do, how do you measure something over 7 inches long????

 

Get an 8in caliper.

 

Sadly this is really what you should do. I picked up a really nice on off Harbor Freight for about $30.00 and the PR checker was about $11.00 from Jegs I believe. You should be quite careful and check your result a couple times. You will find that the base circle on the intake and exhaust CAN be different as mine were .010" different. So you will either need to run two different PR's or the better option is to run on sized PR that will meet the preload requirements for both. IE for my lifters I have a preload of .075" and .085". Make 100% sure you are on the base circle as well. Save your self the headache and remove all the spark plugs as well. You arms will thank you. Also make sure that when you remove the rocker at first that you give the lifter a min to go to full length before you start checking. Also make sure you start at about 7.325" on the PR checker. It WILL have a bit of play there but it's a safe place to start without accidentally adding preload.

 

Courtesy of Shane at Thunder Racing. Yes, this does work.

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

 

Sounds like we need a thread like this put up as a sticky. I really appreciate all the great information here!

 

I just installed LS7 lifters and a set of Milled TSP 5.3 heads and my measurement with the PR length checker came in at 7.25" without any pre-load. I (and my motor guy locally) have found that .030-.060" is the LS7 specific pre-load recommendation. So that makes my combination need a 7.28-7.31" pushrod. I'll most likely end up with 7.30" PR's which will tend to be a quieter valvetrain which works for me. I was tentative to do the measurement on my own so my engine guy came over to the house and checked with me a few times to make sure we had it on the base circle etc and we came in at 7.25" a few times which makes us confident in the new length.