6.0 w/ 317 heads

[scott123]

The 317 has a large combustion chamber at 76CC. It drops compression from 9.5 to 8.3 according to the internet/HOT ROD testing.

Anyone ever cut the heads to increase compression closer to 9.0 or would it be better to go with another head?

My first swap was a nightmare as everything was a 'the first time I ever did this' and nothing seemed to go as smooth as it does on TV. LOL

I got this 6.0 at a pretty good deal. I am not looking for an all out dragster but if I can get some solid/reliable power going in I won't be looking at a dogged motor when I am finished...and then trying to chase power from there.

Sort of researching and hoping someone has made the decision prior.

Scott

[Warrens69GMC]

Need to switch to another head IMO. .7 is a lot of compression to make up by milling the head.

317 shows 71cc, did you check the chamber size?

[mongocanfly]

Not sure what hp numbers your looking for...but my stock 6.0 is sure no dog...got 344hp on the dyno..

[scott123]

Which heads are you getting 344hp from?

Like I said, it is in the 'what can I do' stage.

If the 344 is with the 317 heads then I will roll with what I have as I am not looking for a dragster. The 5.3 swap I did was OK but it was bone stock right out of a wrecked truck.

The 6.0 sort of fell in my lap.

Scott

Just trying to figure some things out before I dive in knee deep.

[Warrens69GMC]

I think you saw the 76cc exhaust side, but the CC of the chambers are 71-71.5cc

[71cadc10]

you can mill .030 or .040" off until intake fitment gets a little hokey.
if untouched, they should be 71cc like Warren pointed out

no LS engines came w/ 8.3:1 compression

[mongocanfly]

I had to go and look...mine does have 317s...
If you havnt pulled the heads, then be aware..the head bolts are torque to yield....one time use and will need replaced if you pull them...
Do you know which 6.0 you have?..there is a LQ4 and LQ9...about 20-30hp difference..mine is LQ9

[scott123]

I was told it was a LQ9 but I do not know for sure. It came out of an early 2000's Denali, maybe 03-04, but the front clip is gone and from the driver's door back looks like a horseshoe.

I will go back and re-read about the chambers.

The motor sort of fell in my lap and I had to do some quick google checking to make sure it was something I would be happy with down the road.

After more reading it looks like this will pretty much serve my purpose bone stock, and with a cam/intake change it will be pretty stout.

I like to use the forums because most of the time it is someone here who has actually done the same project and can give advice/input based on what they have done....not so much what they have read.

Thanks.

Scott

[mongocanfly]

id be all over a LQ9...its a sought after engine...
not sure what your putting it in , but mines in the C30..thats a 5000+lb truck..it amazes people at how stout it is...it would surely be fun in something lighter..

[beaterku]

I have an LQ4 with 317 heads. I used stock GM LS3 head gaskets, milled the heads .030, had them CNC ported and running a smallish cam, it made around 475 at the crank. Stock bottom end with dished pistons.

I was originally going to swap out the flat top LQ9 pistons, but was sending the heads off to be ported anyway, so opted to have them milled. Put the comp ratio closer to 10:1. The engine runs great. To be honest, you are splitting hairs swapping heads. A lot of people poopoo 317 heads, but they are just fine.

[scott123]

I told my buddy I would take it. I think it will be OK.

Scott