just verifiying the vvt is working I am trying to figure out why its runs like crap when everything is hooked up properly

 

Do you have a scanner that will show data??

 

How many miles on the LY6?

I did the exact same swap and still feel like it's running sluggish so I think that's just how they are with the stock cam.

Although I did the plugs, wires and seafoamed my motor after I swapped and it woke up a little.

Also when I did my swap I used the ly6 injectors (wish I knew to keep my FF ones) and the truck would start and shut off until it was tuned because the new engine didn't have D.O.D. kinda strange your's ran without a tune.

 

Who tuned it and was it in person or mail order? I would imagine going from a 5.3 to a 6.0 the maf tables need to be tuned.... Along with changing the displacement so the ecm knows its feeding a bigger engine!!

 

My 2007.5 2500HD has the 6YL engine, and yes she feels flat and sluggish on the bottom end, but wakes up and pulls strong about 3500 rpm to 5800.
While doing bolt ons that includes exhaust,intake and mild 93 octane tune it helped less than expected in a cure to help the weak low end power.
I am plan to do a VVT delete and a performance cam 212/224 551/551 LSA 114 with the supporting mods and custom dyno tune. I believe this will give the 6YL nice power 2000 to 6000.

 

If memory serves me correctly all LY6s have the L92 based heads on it with the larger rectangular ports. It will definitely wake up with a cam change, but watch piston to valve clearance, especially if you start to tighten the LSA. The LY6 I pulled apart had flat top pistons with no valve reliefs.

 

The 6.2 pistons have valve reliefs the 6.0 pistons dont...

 

Thanks for the heads up info on LY6 pistons being flat top with no reliefs.
When H&C is going to be done on a stock LY6, confirm that the upgrade cam
has no VTP issues.

 

Correct.... Good idea on any build, though...