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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[ls1frc]

Yeah car wouldn't run if it were out 180 anyway and you'd have catastrophic damage on first crank.

Edit, actually 180 out might not cause damage at all it just wouldn't run. The valves would still follow the piston in the same fashion, but the fuel/spark wouldn't fire at the right time.

 

[1BADI5]

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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Ok, great.

I hope you get some good news then. No one wants the time and energy spent to go to waste.

 

[1BADI5]

Yeah car wouldn't run if it were out 180 anyway and you'd have catastrophic damage on first crank.

Edit, actually 180 out might not cause damage at all it just wouldn't run. The valves would still follow the piston in the same fashion, but the fuel/spark wouldn't fire at the right time.

I wish i could find the video, this dude on YT had it off by 180* and it ran......he went to tune it and of course it didn't pick up power. His tuner told him to check the cam timing and no shit it was off by 180* (or at least thats what he claimed)

 

[ls1frc]

Yeah it may just barely run, it's just the valves are opening/close on the wrong strokes. Having it like 20-30 degrees off would be a lot worse and would lead to piston smacking.

 

[Geotrash]

Good stuff, Mike and Jeremy - the discussion is helpful to me, as is your expertise.

The engine was making great power, even when the loudness of the noise increased during my last highway test drive. Here are the next steps I'm going to take in case anyone is interested:

1. Pull the rocker cover on the driver's side and use a pushrod length measuring tool to get the correct pushrod length for the specified preload on cylinder #1 for starters. The pushrods are currently 7.425", which I reported incorrectly earlier as 7.400"
2. Remove the rockers on the driver's side and check that they're all lined up and even with a machinist's straight edge.
3. Measure the endplay in the rocker trunnions.
4. Report back to Roger with my findings.

Roger confirmed that the additional oil galley I observed in the stock camshaft is only there for the DoD system, and is not needed for this cam in this engine. Whew. Mike, I believe you were thinking it's for the VVT system. Perhaps it's both for VVT and DoD, but Roger mentioned DoD specifically.

 

[ls1frc]

Thats incorrect, the oil hole is for VVT cam. DoD lifters are controlled through the oil passages under the valley cover.

He mixed up vvt and dod. You dont have either so its a moot point.

 

[ls1frc]

Another thing i noticed from your build is youre using a vvt oil pump. You have too much oil volume for your setup. Doubt thats your issue but worth noting.

On a fixed cam setup you want melling 10295 or 10296

 

[Geotrash]

Another thing i noticed from your build is youre using a vvt oil pump. You have too much oil volume for your setup. Doubt thats your issue but worth noting.

On a fixed cam setup you want melling 10295 or 10296

Yes, you're right. That's partly why I didn't install the Melling HV pump I'd bought and kept the factory in place - I didn't know what the end result would be for oil pressure. That said, since the factory pump is a high volume unit on the DoD engines, I didn't expect an oil pressure drop when removing the VLOM and stock cam, but that's what I'm experiencing. Roger suggested that with a cam like my new one, 15w-40 would be recommended anyway. So I will switch to that once we get this current problem sorted and see if that helps. If not, I could always replace the pump later with one of the models you suggest. Sound reasonable to you?

Someone also mentioned the different color o-rings. The one in my pump from the factory was red, so that's what I replaced it with. Not sure if that was the right choice, but it's what I did. Should I have gone a different way?

I have to say though that for the little time I ran this cam so far, I *love* the low end power. It's a very noticeable difference from stock. You can feel it in the seat of the pants - very little throttle leads to more power than I was used to at a lower RPM. Sweeeet!

 

[ls1frc]

Just run the factory oil, you have a stock engine. On the oil pump, the color can be different depending on what brand the o-ring is. On Melling, the proper o-ring is green. What matters is the thickness. Trucks use the thicker o-ring.

What is your oil pressure at idle?

 

[ls1frc]

Could also be the trunion kit you installed. I used a BTR one years ago, it was scored and ruined within 5k miles. I run stock or go with the CHE bronze stuff. Stock is fine in 99.99% of applications. There were a few that spit needle bearings out years ago and scared the entire ls1 internet, so a trunion business was born.