Occasional light lifter tick starting

[rdezs]

Just googled the procedure.... You'll find detailed write-ups in articles on summit racing's website, Hot rod magazine and such. Once you get the idea you'll see how simple it really is.

Regarding the trunion upgrade, I side with the group that uses the needle bearings in the upgrade kit. They're enclosed much better than OEM. I've read about too many failures with the kit that uses a bronze bushing instead of bearings. Some failed rather quickly, sending bronze grit throughout the engine.

 

[rdezs]

https://www.enginelabs.com/engine-tech/engine/tech-tip-checking-setting-lifter-preload-ls-engine/

https://www.motortrend.com/how-to/1...d-can-cost-your-engine-power-and-performance/

 

[donjetman]

Great. Now I have yet one MORE variable to look at to figure out why I've suddenly developed a tick but have no looseness in installed (original) rocker arms.

Did you do a write-up for determining all of your pushrod calculations?

Youtube has a lot of video on this.

 

[dkad260]

The LH side started ticking a few weeks ago, I figured if the RH side was ticking the LH wasn't far behind. I bought all 16 rockers when I did the RH side but put the rest on the back burner.

Today I changed out all 8 on the LH side, I was going to swap all the pushrods until I checked the price, $30 per rod, will wait on that. If I had to guess, it's either #3 or #5 exhaust as they both have a good deal of play. All back together and it's quiet again.

 

[donjetman]

The LH side started ticking a few weeks ago, I figured if the RH side was ticking the LH wasn't far behind. I bought all 16 rockers when I did the RH side but put the rest on the back burner.

Today I changed out all 8 on the LH side, I was going to swap all the pushrods until I checked the price, $30 per rod, will wait on that. If I had to guess, it's either #3 or #5 exhaust as they both have a good deal of play. All back together and it's quiet again.

I've bought pushrods for my LS engines recently for less than $10 each.

The ticking noise is probably caused by pushrod(s) that are too long.

Get on youtube and learn how to check/set lifter preload.

 

[dkad260]

The ticking noise is probably cause by pushrod(s) that are too long

The pushrods are OE with 150K miles. The trunion on #3&5 exhaust had a bit more play than the rest. I can see how a longer pushrod can wear the rocker, but how did they grow? Deformation from my understanding would shorten them correct?

 

[rdezs]

There's a few things that affect pushrod length at 150,000 miles. The ends of the pushrods themselves wear. The rocker itself wears at both ends. You pull the heads to replace the lifters, have the shop skim the head to make sure it's flat, you've changed the mathematics involved. That's why it's always a good idea to check your push rod length and get the correct size. Usually we're talking very small differences in length. And yes, a lot of people drop LS7 lifters in with new.... Or their old push rods.... And it works just fine. The point in measuring the push rods, is to get it perfect. So it can go another 2 or 300,000 miles.

 

[donjetman]

@dkad260 , I'll try to explain how to set LS engine lifter preload on a stock engine.

First you need to measure a pushrod. I have a friend with dial calipers that measure up to 8".

I removed a rocker arm, then the pushrod, that was on the base circle of the cam. You can tell it's on the base circle because it feels a little loose when you grab the rocker arm tip and move it side to side. If it's on a ramp of the lobe it will be tight and not wiggle. When on a base circle it will wiggle.

Measure it. Mine was 7.388" long. I assumed the other 15 were too.

Now reinstall the pushrod. Reinstall the rocker arm. Tighten the hold down bolt until it is just finger tight (zero lash). Now, using a torque wrench, count the number of turns it takes to reach 22 ft lbs. If less than 3/4 turn pushrod is too short. If more than 1 1/4 turns pushrod is too long.

Check the preload of all 16 this way. Write down the # of turns for each. Some rockers will be tight because they are on a ramp of the camshaft. After checking all the loose ones using this method bar the engine crankshaft over around 270* to 360* degrees.

Now, many rocker arms that had been tight will be loose because they are now on the base circle. Now loosen those hold down bolts and retighten it until finger tight (zero lash) then check and record how many turns it takes to reach 22 ft lbs. Again, If less than 3/4 turn? pushrod is too short. If more than 1 1/4 turns? pushrod is too long.

Keep doing this procedure until you've recorded the # of turns it takes for all 16 valves.

With one of my LS engines only 2 of the 16 lifters had preload that fell in the 3/4 to 1 1/4 turn range, the other 14 took more than 1 1/4 turns and needed a shorter pushrod, either 7.350" or 7.375" to get them in the correct preload range.

LS pushrods can be purchased in many lengths from many sources for <$10 each.

 

[dkad260]

There's a few things that affect pushrod length at 150,000 miles. The ends of the pushrods themselves wear. The rocker itself wears at both ends. You pull the heads to replace the lifters, have the shop skim the head to make sure it's flat, you've changed the mathematics involved. That's why it's always a good idea to check your push rod length and get the correct size. Usually we're talking very small differences in length. And yes, a lot of people drop LS7 lifters in with new.... Or their old push rods.... And it works just fine. The point in measuring the push rods, is to get it perfect. So it can go another 2 or 300,000 miles.

I agree with all of that. In my case however, this is the first time these valve covers have been removed since new. There's very little preload on these lifters, and the worn trunion removes most of that lash. These rockers get tightened to 22 ft.lbs, there's no backing off or adding preload, you get what you get without doing more work. I understand the areas of wear, just this is the first motor I've owned that had a noticeable light tick from a worn rocker trunion. No worries, easy to replace.

 

[dkad260]

Now, using a torque wrench, count the number of turns it takes to reach 22 ft lbs. If less than 3/4 turn pushrod is too short. If more than 1 1/4 turns pushrod is too long

We replied at the same time. Interesting to know, thanks.