Anyone have the factory specs for cast number (852) heads?

[whitesilvy04]

anyone?

[RedHeartbeat]

61.15cc Chamber Volume
9.5:1 compression on a stock 4.8 or 5.3
200cc Intake Port Volume
70cc Exhaust Port Volume
1.89 Intake Valve Diameter
1.55 Exhaust Valve Diameter

Putting these on an LS1 engine yeilds 10.9:1 compression. Milling .030 off the bottoms will yeild 11.5:1 on the LS1 5.7L engine. Intake valve upgrades are recommended for performance applications.

[whitesilvy04]

Sweet thanks for the info man i wanted to compare them to the 706 heads and work my ideas from there....

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

852 heads

61.15cc Chamber Volume
9.5:1 compression on a stock 4.8 or 5.3
200cc Intake Port Volume
70cc Exhaust Port Volume
1.89 Intake Valve Diameter
1.55 Exhaust Valve Diameter


They both have the same specs??? thats weird... so whats the difference between each other??

[RedHeartbeat]

You had the data already. The 706/852 is just the last three numbers of the PN on the head.

[whitesilvy04]

lol, oh dang....I just now noticed that....

[whitesilvy04]

ok... i knew something wasnt right with what my brother was telling me i guess i got the info confused...

the heads he pulled off are "243" heads.... but from what i've been told that those heads will actually hurt my truck... I thought that they would boost my compression and since they have a bigger intake valve they would be a better set head then my 852's

[TXsilverado]

would you like to sell the 243's? if so PM me a price.

[whitesilvy04]

Sorry, I'm going to keep them... i'm still planning on using them just not on my 4.8L