Occasional light lifter tick starting

[Bob K7]

I presume from your reference to "the dealer" that you used GM OE rocker arms for replacements rather than an aftermarket variety?

 

[rdezs]

I'd be replacing the push rods as well.... They are wear item. Inspection with a micrometer will reveal just how much wear has occurred

 

[donjetman]

I'd be replacing the push rods as well.... They are wear item. Inspection with a micrometer will reveal just how much wear has occurred

Yes, LS valve train noise is usually caused by incorrect lifter preload because of valve train wear and the incorrect pushrod length.

I just changed 14 of the 16 pushrods in my C5 LS1 with two different shorter lengths (7.375" & 7.350") to get the preload correct and now it's quiet.

Preload turns of the rocker arm hold down bolt from zero lash to 22 ft lbs should be 3/4 turn to 1 1/4 turn. If it takes more turns? pushrod is too long.

14 of my pushrods were too long, 7.388, and took more than 1 1/4 turns.

Youtube is your friend.

 

[j91z28d1]

that's interesting, every ls build I've seen throws 7.40 pushrods in and doesn't check anything.

I'm guessing you didn't check this because of a cam swap? Just checking the stock setup?

 

[j91z28d1]

I presume from your reference to "the dealer" that you used GM OE rocker arms for replacements rather than an aftermarket variety?

this is a very old thread so they probably don't reply.

but yes, those look to be new oem rockers. but that said, it seems the common thing these days is to order a bushing kit and replace the bearings in the stock rockers with bushings. said to last longer and if they do fail not leave timing roller bearings all inside your engine.

 

[donjetman]

that's interesting, every ls build I've seen throws 7.40 pushrods in and doesn't check anything.

I'm guessing you didn't check this because of a cam swap? Just checking the stock setup?

Totally stock w/79k miles.

A lot of people think noisy valve train is normal. Its not, so I did my research and took care of it

 

[solli5pack]

Well this is an interesting read. I wasn't aware of the rocker arm bearings wearing out causing a tap. About 6 months after my AFM delete I started hearing a tap after start up that would go away while driving. It's been slowly getting worse. I assumed it was the Summit lifters but now with 175k on my stock rockers I have something else to check.

 

[rdezs]

You might check the screen under the oil pressure sending unit.

Most likely it's either worn/incorrect length push rods or worn rockers/trunion bearings. (Assuming your oil pressure is good)

Get yourself a pushrod length checker, pick up a kit to replace the trunnion bearings..... Check your preload using your existing push rods after replacing the trunion bearings..... Then measure your existing push rods and determine if you need slightly longer or shorter push rods to get the preload right..... Then order the correct push rods.

Keep in mind if you reused your push rods, they have worn a little bit shorter. You will need a digital caliper to measure length.

I recently went through an LS engine, switched over to LS7 lifters, and ended up going with 7.375". OEM is 7.4"

This is one area you don't need to stick with ACDelco or OEM stuff. There's several good aftermarket brands with thicker walled push rods.

 

[petethepug]

I like this thread! So much good LS shop talk.

Makes me want to start a discussion with my wife about it and just before she nods off throw in … “and that’s why it’s such a good idea to save money on labor and parts by installing those new billet TrickFlow heads on the truck, right?”