Sounds like it has enough timing, possibly a hair much.

To know for sure if the cam is right you need to check it with a degree wheel. The cam could be off a bit itself.

 

Pooter, good catch on the bore spec! I had to look up the LS3 bore spec, and it's bigger than what he said he bored to! lol
I bet he has an LQ4 or LQ9 block being it's cast iron, which I caught from the first post.
Also seen from the first post, he says it has only top end power, which indicates to me a retarded cam.
I remember my '78 Ford E-250 van with 460 had the factory retarded cam and it couldn't get out of its own way. It ran out of breath before the cam had anything to say...

 

we did not go further in boring to be on safe side. 4.030 is safe maximum on LQ4/9 cast iron block

 

You mentioned in your first post a cast iron 6.2 block. That does not exist in stock form, which is what confused some of us. So you have a 6.0 block, which as you NOW say is a LQ4/LQ9 block.

 

Sorry for confusion. Block is 6.0 liter LQ4, bored to 4.030, so it is not 6.0 anymore. donor engine itself came from Hummer H2. But I mentioned in the first post that the block was cast iron, so I assumed that it came from LQ4/9 engine

 

OK, no matter what an engine is bored to, it is always referred as the OEM size. In your case, 6.0. That way we all know what we are talking about.

 

definitely lose the header tape as previously mentioned. will rot those headers after 3-5 years

 

I have ordered camshaft timing kit from Comp Cam, once it will arrive I will try to retard the camshaft. Why retard? my camshaft is 281lrr hr-13, LSA is 113, intake lobe centerline is 109, so this camshaft is factory advanced by 4 degrees. what do you think, am I at the right way?

 

Why not just run it the way it comes? Got to be a reason for making it as it is...

 

I'm currently running camshaft as-is, and I think it is a reason for my glowing headers and low torque, that's why I want to adjust it

 

 

can't remember exact numbers, but it was 16.5 average AFR

 

Sounds a bit on the LEAN side of things….

 

 

I'm thinking the lean mix is at least part of the red-header syndrome.... retarded timing would be the rest...

 

That'll make your problem worse..

He's the very definition of an askhole

I give up.

 

I do not think messing with your cam is the answer here unless you replace it with a smaller cam. The cam needs compression as stated above. Advancing the cam will get you back some dynamic compression, but will open exhaust earlier. Regarding the cam will give up more torque with no benefit.

Red headers tends to be low idle spark, like under 15 degrees. LS likes 18+ degrees at idle. Other cause is lean condition at idle or both. This can fool you because some cams like to idle lean. But it is actually false lean due to overlap. Keep running it, eventually your oxygen sensor will overheat, ignite, burn up your harness, and your low torque issue will be long forgotten. Or solved. Depending on your point of view. I doubt only one primary is glowing. More likely the wrap is hiding it. Take the wrap off I bet your headers are a really cool looking purple.

You do not need expensive pistons to gain compression. Just mill the heads and go to a thinner HG. But honestly, I think your cam is just too big. If you post a tune file we can look. I will reserve judgement until then.

 

idling at 16.5 isn't going to blow stuff up or cause glowing headers. As mentioned above, my money is also on timing whether it be ignition advance or cam timing.

 

when all of you mention ignition timing, do you mean ignition timing in ECU itself, or mechanical relationship of crankshaft to camshaft?

 

It could be either. If the ignition advance set in the computer is too low it could cause the issue, same thing if the cam is ground wrong or installed wrong and retarded.