Originally Posted by 427ls1

The weight of the cast iron block is 210.4 lbs, the alluminum block is 92.5 lbs. Means someting to some people. I'm currently in my build of a cast iron LQ-9 6.0 2002 truck block stroking it to a 427. I've done 383's and stock ls1's, ls2's and ls6's, but i think for the beating I'll deliver on this engine i'll stick to cast iron. The 6.0 LQ-4 casting 317 alluminum heads are as good as any ls1, ls2 and ls6. THe Chamber size is a little bigger, but works with most stroker combinations. These engines tend to have the piston come up above the deck with an aftermarket rotating assembly so make sure u check your gasket thickness before slapping her together. Stock gaskets are .050 thick! I just had a customer bring me a set of patriot heads to bolt on to his 383 stroked ls6. I'd stay away from those heads, just alot of money for throwing a cnc machine on it.

Here are some specs on stock heads taken from jrp at ls1tech.com, this guys taken the time to post this so we dont have to research it all. He's got port flows and everything else listed here too. Thanks JRP!


just look for posting: JRP's FAQ For Commonly Asked Questions



Casting Number 241
Head: 1997+ LS1 5.7 Litre Passenger Car
Material: Aluminimum
Part Number:
12559806 (1997-98) Chambers = 69cc
12559853 (1999-00)
12564241 (2001-03)
Combustion Chamber Volume: 66.67cc
Compression Ratio: 10.1:1
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches


Casting Number 243
Head: 2001 LS6 5.7 Litre Passenger Car
Material: Aluminimum
Part Number:
12564243
Combustion Chamber Volume: 64.45cc
Compression Ratio: 10.5:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Casting Number 706
Head: 1999+ LR4 4.8 Litre Truck
1999+ LM4 /LM7 5.3 Litre Truck
Material: Aluminimum
Part Number:
12559852
12561706
Combustion Chamber Volume: 61.15cc
Compression Ratio: 9.5:1
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches

Casting Number 373
Head: 1999-2000 LQ4 6.0 Litre 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 Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Casting Number 317
Head: 2001+ LQ4 6.0 Litre Truck
Material: Aluminimum
Part Number:
12572035
Combustion Chamber Volume: 71.06cc
Compression Ratio: 10:1
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches



It takes about .005" milling of the block deck to remove 1cc of volume. It takes .007" milling to remove 1cc from an LS1 head