2012 Yukon XL Denali 6.2L Cam Swap Thread

[ls1frc]

Totally normal cam noise.

You still want to measure pushrod length because dialing in preload can lessen that noise to a degree. The adjustable pushrods are only like 25 dollars. You just have to get a valve on the base circle of the cam, pop the rocker off, put the adjustable pushrod in and keep adjusting it until you have zero lash. Then add preload to that measurement.

 

[Geotrash]

Totally normal cam noise.

You still want to measure pushrod length because dialing in preload can lessen that noise to a degree. The adjustable pushrods are only like 25 dollars. You just have to get a valve on the base circle of the cam, pop the rocker off, put the adjustable pushrod in and keep adjusting it until you have zero lash. Then add preload to that measurement.

Thanks Mike - that's a huge relief to know. Adjustable pushrods would be an easy, cheap swap and while I've never done the preload check test, I've read about it and it looks straightforward. Question though - do I need to set the preload individually for all of the valves or can I just dial all of the pushrods to whatever I find is correct for the #1 cylinder?

 

[FrankU]

Sounds exactly like my 6.2 , put the plastic cover on the plenum then close the hood. You did a good job !

 

[Geotrash]

Bad news. Took it out for another ride and that louder lifter sound changed into a loud rapping sound on either cylinder 1 or 3 that gets worse as rpms rise and it also skips a beat or two every 3-5 raps at idle. And it’s accompanied by a chirping sound. Something’s coming apart. Pulled the rocker cover on that side and nothing is loose. Checked for rocker cover clearance and no issues. Borescoped cylinders 1 & 3 and they look fine inside. Best guess at this point is that a lifter is coming apart and slamming into the cam. It’s loud! Next step will be to pull all the rocker arms on that side and the pushrods, and go from there.


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[ls1frc]

You just buy one adjuatable pushrod. You find zero lash. Then add desired preload to that measurement and order pushrods closest to that measurement. On stock replacement, full travel type lifters its not necessary to be precise but you still wanna check to make sure youre not way off


Way too short and the valvetrain will sound bad.
Way too long and the lifter plunger bottoms out and the valve never closes.

Take a video of the noise ur hearing.

 

[Geotrash]

You just buy one adjuatable pushrod. You find zero lash. Then add desired preload to that measurement and order pushrods closest to that measurement. On stock replacement, full travel type lifters its not necessary to be precise but you still wanna check to make sure youre not way off


Way too short and the valvetrain will sound bad.
Way too long and the lifter plunger bottoms out and the valve never closes.

Take a video of the noise ur hearing.

Thanks again. Understood on the pushrods - thank you.

On the video, I would, but I'm afraid to run the engine any more at this point. It sounds like a grenading lifter to my ear. More when I can get it apart. :-(

One thing I'm concerned about is something I noticed when I inspected the new camshaft when it arrived. The original had an oil passageway groove machined into the second cam bearing from the front. The one Roger sent did not. I chalked it up to the differences in an AFM camshaft and one without. What do you think? Potential issue?

 

[ls1frc]

No, the oil channel for the original is for VVT. The VVT uses high oil flow/pressure to control the cam timing at the phaser.

If you pop off the valley cover, you can see a couple of the lifters and the camshaft lobes.

 

[1BADI5]

Some of my concerns based on the information that has been provided up to this point

1) cam timing - I think your mechanical timing is off based on the way you explained setting it; there are countless videos on YT that show you how to properly set cam timing on a LS motor. The cam sprocket is indexed via the dowel pin on the cam.

2) oil pump - reused the old one???, tech tip, if your in there replace it

3) oil pump pick up o-ring - there are 3 different size (red, green and black)

4) 3/4 are contributing to the low oil psi. I went from 22-25 psi at idle to 47-51psi at idle when I did my AFM and VVT delete (I also installed a TSP Stage 3 5.3 high lift cam and 225 heads)

5) lifter/rocker noise on a fresh top end should only last 1-3 mins upon start up depending on how you primed the oil system. The fact its getting louder almost verified that #1 is the root cause.

I guess I need to re-read your parts list.

- When I did mine I replaced
New OEM rockers w/trunion upgrade
Real GM LS7 lifters
New OEM 3 bolt cam sprocket
New cam retainer plate
New OEM lifter trays
New OEM head gaskets
MMS 5/16 7.400 push rods
PAC .660 valve springs
Katech C5R timing chain
New OEM high volume oil pump
New black o ring on the pick up tube
Oil pick up tube clamp (secures the other side of the pick up tube
LS3 front cover with BTR cam sensor wiring adapter
L59 valley cover
New OEM oil psi sensor
New OEM water pump
All hardware was replaced with ARP stuff

 

[1BADI5]

This is how the proper cam timing should appear with #1 at TDC

If I read your post correctly, you said you had both timing marks at the 12 o clock position....if so, your cam is off by 180*

 

[Geotrash]

Thanks again, Jeremy. To clarify the cam timing point, when I installed the camshaft sprockets they were aligned precisely as you describe (cam at 6 and crank at 12), and the dowel was firmly in the hole as well. I was very careful about this. The 12 o’clock and 12 o’clock mention were specific to adjusting the rocker arms with the number one cylinder at top dead center. If the camshaft were 180° out, I wouldn’t expect the engine to run at all, and would expect to have some valve interference issues.

I’ve been corresponding with Roger today, and he has some things he wants me to check. I will report back here with what I find, but his support has been exceptional.


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