No what kills the torque is the sewage pipe intake ports and low flow velocity at low engine speeds coupled with lessened demand from small cylinders. You can time the cam all you like but it still will not make up for those heads flow characteristics.

Works great in a Camaro or a regular cab short box with no weight. Go actually drive some ly6 2500s daily and come back with your same statements. Those heads are utterly useless in a heavy application naturally aspirated on small displacement engines being something that is only 364 cid.

 

If you say so.

 

Quick update guys. I just found a NTO (under 100 miles) through Powertrain Direct...actually A&P Engines,who is a distributor for them. Its an LY6 vin K from a Silverado 2500HD. Dan, one of their salesmen found 3 new take outs (theres 2 left if anyone is in need). I ordered it this morning and i'm waiting to hear back for an ETA on arrival. He thought it was 2-3 days but is supposed to confirm. Total cost was 3400 shipped to my zip plus 200 core charge. Engine supposed to be complete dropout with manifolds, intake, accessories.

I'll post again when i get it in front of me, thanks for the assistance so far guys.

Barnes

 

I'm trying to get the parts together for the VVT delete on the new 6.0. Is it possible to keep the stock camshaft or will i be required to swap? I have the timing cover from the 5.3. I'm ordering a new crank seal and a new cover gasket for that. Most of the kits i see come with "3 bolt conversion sprocket" I'm not opposed to the cam swap, but my new engine does come with a 1 year warranty.....but if you guys say swap the cam i'm gonna heed your advice.

 

Pretty sure you need a new cam. the VVT cam has a odd setup if im not mistaken.

 

Thanks for confirmation. I've been speaking with a tuner shop down in NC and they're putting together a vvt delete and custom cam for me.

He mentioned an LS3 cam as a cheaper option, but recommended doing a custom grind cam...saying he can get about 30 more hp, but still be unnoticeable. Looks like thats the direction i'll be going. PCM of NC by the way if anyone has any opinions. Just ordered : How to Build and Modify GM LS-Series Engines

Hopefully that'll bring me a little more up to speed on these. I'm much more comfortable with Gen 1 SBCs and carbs....but i hope to change that.

Engine will be here tomorrow finally.

 

Hate to break it to you but he is right. The ports in the rectangle heads are too large. Will they make power? Absolutely, especially if coupled with the proper cam. The smaller, higher velocity ports in the cathedral heads will make more usable power throughout the power band he's looking at. Above low .600ish lift and high rpm is where the rectangle ports take over. While the stock 799's will most definitely lose up high, they will absolutely kill that bloated, sluggish rectangle port anywhere under a mid .500 lift. Port the 799/243s and it's a tossup up high until probably 7k rpm where the rectangles will probably squeak out a few more ponies, but by then the intake is out of breath.

I'm not saying they aren't great heads, but for what he's looking at doing it's not the best choice. I'd reuse the cathedrals and sell the rectangles to make up for some coin if it were me though. Those smaller, higher velocity ports will make a killer torque curve with the right cam.

 

5.3 to 6.0 swap is pretty easy

Use your old 5.3 heads/intake/injectors - everything from the top side of the original engine
Use the original front timing cover also, with the oil pan - if it has the low oil level flow

New engine, if it was me, I would get the 212/218 high lift with the yellow Z06 springs and hardened 7.4 push rods. There's no bottom end loss at all. It's ment to work with the stock converter and has a smooth idle

The cam from the LY6 is a VVT cam, toss it out, along with the cam gear, cam cover, and the small jumper harness

what do you need for swap:
original 5.3 motor mounts
12589227 new 6.0 head gaskets
17800568 new head bolts
12586481 4x trigger cam gear
12630223 water pump gaskets
3 bolts for the new cam gear
2 gallons of antifreeze
oil and filter
new tune

when you put the new engine in the suburban, install the manifolds, and balancer before it's lowered in. - less leaning over work later on

 

Thanks tootall, i was just watching some youtube vids of your truck(s) just before checking in here. Impressive.

Thats perfect and exactly what i need, a good list to follow.

I got home this evening to a LY6 sitting in my driveway. I had just enough time to get it in the shop on the picker. I'm gonna mount it on another stand tomorrow...anyone know the specs on the bellhousing/tranny bolt threads? I made some standards work on the old 5.3 but dont wanna screw up the 6.0 threads.

The 212/218 high lift cam you mention is that a comp off the shelf cam?

Promise some pics tomorrow to get things rolling, but here's a few quickies:

Wasnt able to upload hi res pics for some reason...and they're sideways. kinda useless. sorry

 

oh yeah, meant to ask....do i need a new intake gasket? it seems like it might be a reusable one. And the exhaust manifold gaskets?

and not to open up another can of worms, but headers maybe?