2012 Yukon XL Denali 6.2L Cam Swap Thread

[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.