I own a 2004 Escalade ESV with LQ9 Engine, 6.0l Vin N, 50 000 miles on it.

Having a misfire on cylinder #2, I found out a leak on intake valve and decided to replace the whole valvetrain with Comp Cam pushrod (7.40inch), Sealed Power V-4593 exhaust valve , Sealed Power V-4644 Intake valve, Comp Cam spring 26915CS.
I've bought the Harland Sharp SLS17, but due to clearance issue with heads and installation issue, I decided to go back with OEM rockers.

My concern here is with OEM rocker arm installation: following the GM procedure, cyl#1 at TDC, when torquing to 30Nm, the valves open a little.
I guess it shoud not...

I made a leak down test without rocker arm, and the % of leak is between 2 and 4% on all 8 cylinders.

With rocker arm installed and torqued to 30Nm on Cyl#1, I have up to 10% of leak.

Will the lifters compensate the extra pressure once the engine runs? ...Any idea on this?

Thanks guys

 

Stock cam? Once youve installed the rockers, its not far away from starting it, why wouldnt you start the engine and see what happens? Im almost sure the lifters will compensate for it. And the pushrods are a bit longer but if you have hydraulic lifters, they should compensate for that.

 

Yes stock cam, with new lifters part GM 12499225.
Why do you think the pushrods are a bit longer? 7.40 is the same lenght as stock.
I will check again the installation before going to start the engine. I don't see what can I do better...unless lifters can compensate as you wrote. Thanks

 

Oups... forgot to mention that these lifters never ran so far... just soaked into oil before installation. Maybe pushrods are a little bit "pushed" by the lifters even beeing onto cam circle...?

 

Are you at TDC on the compression stroke? Or the exhaust stroke?

 

yes at TDC on compression stroke, I check it with a vaccum-fuel pressure gauge. Anyway, I check again this afternoon everything.

 

Stock pushrods are like 7.380 or something ive read. Cant say for sure. But thats not that big of a difference so the lifters should compensate for it. And also make sure the pushrods are seated in the middle of the lifters. Just wiggle them around until you feel they are seated tightly.

 

You're right, I missed that, don't know how! Stock pushrod is P/N 10238852, lenght is 7.325 inch, while the COMP Cams Magnum Pushrods 7638-16 I've bought are 7.40 inch....

That beeing said, I had a good surprise this afternoon when I recheck cyl#1 with the rockers installed yesterday (only on this cylinder): I made a leak down test again and the leak is back to 2%!
Then I measured the height of springs with cyl#1 @ TDC (with the rocker installed): intake is 46.60mm and exhaust 47.0mm. Compare to cyl. #3 with no rocker on it: intake is 46.65mm and exhaust 47.29mm.

The only explanation I have is the lifters: as they were new, maybe some air was still inside in spite there were soaking into oil before installation. I guess that all the night the lifters "released" the air and adjusted to the proper pressure onto the pushrod. Maybe someone will have a better approach.

I plan to restart the engine on Monday with the Comp Cam pushrods, if it goes bad, I go back with stock pushrods, and maybe with the Harland Sharp rockers.

 

Good to hear that! And about the lenght i wasnt sure either, but i knew stock was shorter then 7.400 but you still should be good with them. Good luck!

 

Done! I started the engine today (with 7.40 pushrods), no more misfire at idle!
Idle is very smooth, no specific noise, at higher RPM I feel more power.
Plus the wrap on the stainless steel headers, no more echo inside the truck.
Will post on a later on some videos I've made of the heads rebuilding.
Thanks to this forum and all of you.