The 02-04 LQ4 and LQ9 heads have the same combustion chamber size (71cc), same intake/exhaust port volume (210/75), same casting number (12562317), same machined numbers (12562318) and same final assembly numbers (12565363).

There is a final assemby number of 12565364 for the LQ4 heads which is good for the KL5 natural gas engine.

The LQx heads were designed straight from the LS6 heads, as they all share the same intake and exhaust ports.

I can find no differences between the LQ4 and LQ9 heads, other than the fact the 99-01 LQ4 heads had different part numbers. But the LQ9 was not offered during that time period.

 

They are the same..... Different on an LS2 of course. But LQ4 and LQ9 heads are the same. 6.0 heads are just bigger chambered ZO6 heads. Check the casting numbers on LQ4 and LQ9 heads. They are 317 castings aside from the older cast 6.0 heads. See if you can spot your casting numbers on your heads. If my memory serves me, I think they are on the front of one head and the rear of another(which u wont see).

Head: 1999-2000, LQ4 6.0-Liter Truck
Material: Cast Iron
Part number: 12561873
Combustion Chamber Volume: 71.06cc
Compression Ratio: 9.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diamter: 2.00-inches
Exhaust Valve Diamter: 1.55-inches
______________________________
Head: 2001+, LQ4 6.0-Liter Truck
Material: Aluminum
Part number: 12562317
Combustion Chamber Volume: 71.06cc
Compression Ratio: 9.4:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diamter: 2.00-inches
Exhaust Valve Diamter: 1.55-inches

________________________________

Head: 2002+, LQ9 6.0-Liter Truck
Material: Aluminum
Part number: 12572035
Combustion Chamber Volume: 71.06cc
Compression Ratio: 10:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diamter: 2.00-inches
Exhaust Valve Diamter: 1.55-inches

 

Those 99-01 LQ4 heads with the different part numbers are probably the older cast iron heads. The current heads are aluminum but the 6.0 had cast iron heads for a while before beng upgraded to the aluminum ones.

Sorry I see Jared already mentioned the cast iron heads.

 

I hope all that info is correct. I did a bit of searching for the head specs.

 

Thats what I though man. But a while back somebody posted pics of LQ4 and LQ9 rods/pistons. And the Q9 parts were way beefier. Especially the rods!!

 

Hey Jared,

For the LQ4's, you listed the casting numbers as the part number (these correspond with the same casting numbers that I have), but where did you get that number you listed for the LQ9? The only numbers I have for the LQ9 I listed above in a previous post and that one was not any of them.

 

Sorry guys I didn't really know what I was talking about that was just what I heard You know how that goes. Does anyone have the specs on the new C6 heads

 

Casting number - passenger side, towards front of truck. (If I'm remembering right).

I think 317/035 heads are identical spec wise.... It was all in they way they were made. (Something to the effect of one being sand cast, and the other something else).

I'm quite sure the 035's were the least common ones - while the 317's (that I have) were the more common/cheaper ones.