Advice and Parts recommendations for some 6.2 cam/valvetrain work?

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Camar068

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Bextreme04

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Well, I got it swapped out and started right up. Sounded good and ran decent on the stock 2011 Yukon 6.2 OS I swapped in to start with. Then it started making a slight knocking sound... which then got worse and worse until I had to shut it down and investigate. Pulled my hair out and started going through the 6 stages of grief for a day or two before digging in to try and figure out WTF last night. I was sure it was too long of pushrods collapsing the lifters, then I was sure that the sound was too terrible for that and it must be a delphi LS7 lifter coming apart(damn you Michigan motor sports!!!!), but then I started thinking it might be a spun bearing because it was THAT terrible of a noise. Then when I removed the rockers and pushrods and went to manually turn over the engine.. it made a solid "clunk" every time you turned the crank even a little bit!

Climbed under it and had my brother in law turn it and sure enough.... flexplate bolts are loose(or maybe flexplate broke). So now I get to pull the transmission back off enough to put some red locktite on the flexplate bolts and torque them back down to spec.

I'm still not sure if I forgot to torque them originally or if something else is messed up, but I'll find out tonight. I'm torn between pissed off I screwed something so simple and annoying to fix up and being relieved I didn't spin a bearing and destroy my fresh engine.
 

Hunter79764

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Been there, done that, where the simple fix nearly passes you off more than makes you feel better... here's hoping it just slipped your mind and wasn't torqued with no further harm...

I chased an intermittent stall under load on my Monte Carlo 5.3 swap years ago. Took me weeks of hair pulling and stress and headache and diagnosing before I found a ground wire on a loose bolt, and under throttle the cable flexed and bumped the harness, making it hop across the teeth of the bolt, and losing ground for injectors or coils or something, causing my stall. I was so relieved but so upset that it was something that simple, just tighten a bolt...
 

Bextreme04

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Been there, done that, where the simple fix nearly passes you off more than makes you feel better... here's hoping it just slipped your mind and wasn't torqued with no further harm...

I chased an intermittent stall under load on my Monte Carlo 5.3 swap years ago. Took me weeks of hair pulling and stress and headache and diagnosing before I found a ground wire on a loose bolt, and under throttle the cable flexed and bumped the harness, making it hop across the teeth of the bolt, and losing ground for injectors or coils or something, causing my stall. I was so relieved but so upset that it was something that simple, just tighten a bolt...
Well, they were definitely not torqued. I got the trans pulled back enough on some 4.5" long bolts threaded into the bellhousing and removed, loctited, then properly torqued the bolts in. Horrible grinding clunking sound is completely gone.

I had quite a big oil leak from the oil galley plug behind the power steering pump, just had to remove it and put some PTFE thread sealer on it and torque it in and it was fine.

Now I've gotten into the tuning part of it and have spent some time trying to get the VVE tables dialed in and get it to idle right without surging and stalling out. It was about 50% less VE in the idle and low speed cruising areas. Get's pretty much right on the stock VE above about 2500rpm through 3500rpm, then quickly takes off above 3500RPM. It's insane how much more power everywhere the 6.2 has compared to a 5.3. Gets the same or better fuel mileage everywhere as well. The long tubes and full intake/exhaust help a bunch I'm sure too.
 

Hunter79764

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Well, they were definitely not torqued. I got the trans pulled back enough on some 4.5" long bolts threaded into the bellhousing and removed, loctited, then properly torqued the bolts in. Horrible grinding clunking sound is completely gone.

I had quite a big oil leak from the oil galley plug behind the power steering pump, just had to remove it and put some PTFE thread sealer on it and torque it in and it was fine.

Now I've gotten into the tuning part of it and have spent some time trying to get the VVE tables dialed in and get it to idle right without surging and stalling out. It was about 50% less VE in the idle and low speed cruising areas. Get's pretty much right on the stock VE above about 2500rpm through 3500rpm, then quickly takes off above 3500RPM. It's insane how much more power everywhere the 6.2 has compared to a 5.3. Gets the same or better fuel mileage everywhere as well. The long tubes and full intake/exhaust help a bunch I'm sure too.
Glad it was relatively simple, loose bolts are much better than a handful of other culprits...
When you get to a moderately happy place on the tune, would you be willing to shoot me a copy to compare to mine?
 

Bextreme04

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Glad it was relatively simple, loose bolts are much better than a handful of other culprits...
When you get to a moderately happy place on the tune, would you be willing to shoot me a copy to compare to mine?
Yeah, no problem. My wife just drove it to Idaho and is on her way back. I've just got the cruise and low RPM/low throttle portions of the tune somewhat dialed in and she is averaging ~15MPG.. which is pretty decent for 4.10's, 32" tires, and a 6400lb brick. I think once i get the EOIT adjusted for the new cam and get some VVT tuning done it should be able to hit 18-20 or so on the freeway, which will be nice. Right now I have the tune locked at 0 degrees of cam advance except for the high RPM values that TSP provided. Now that I have the GMVE math parameter in there and a good filter on the data, I'm able to get the VVE dialed in with 2-3 fairly short drives.. so I'll probably take a few evening to cycle through the 15 degrees of available cam adjustment to get the VE dialed in for the whole cam and then figure out what cam setting gets the best efficiency at highway cruise. I would expect the stage 2 cam to be very close to the stage 1 for most of the tune, since they are very similar cams.

Do you have HP tuners?
 

Bextreme04

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I also figured out that the stock L92 cam is -12 degrees advanced at the docked position. The TSP cams are 7 degrees advanced at the docked position(hence the mechanical stop that keeps them from having more than 20 degrees of movement). I'm still trying to wrap my head around what effect that should have on the torque curve and whether I should be doing something with that at cruise.
 

Hunter79764

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Yes, I have HP Tuners. I've never gotten close to that MPG with ours, even stock it was around 14 on the highway most of the time, and after the cam, she averages 11-12 (mostly city, down about 1.5-2 mpg from stock). We don't take it on the highway much, and to be fair, highway around here generally means 75-80 mph and a fair number of stop and go portions, so I know we will be on the lower end of anything, but it has always seemed like there is more on the table than what I'm seeing.
 

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