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Old 02-02-2009, 06:16 PM   #1
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Default 862 vs. 706 heads

L33 engine in son's turbo truck has a cracked block. L33 is a higher output 5.3L with aluminum block. Some of the propaganda from Chevy states that the heads on the L33 are LS6 units with bigger valves and bigger ports. Every thing I've read says the 862 (on the L33) are the same as 706 heads. What are the differences? We have an iron block 5.3 (with 706 heads) that we are going to install in place of the L33. The L33 came with 10:1 compression and I don't want to go down in C/R if possible. The 862 heads are ready to go and we can swap them out on the new motor if necessary. Are the ports, valves, and combustion chamber volume the same on these heads? I've done a lot of reading and things are clear as mud. Need a clue because I don't have one.
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Old 02-02-2009, 06:20 PM   #2
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862 heads are not ls6 heads.

read this
http://performancetrucks.net/forums/...=1#post4113890
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Old 02-02-2009, 07:06 PM   #3
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I thought if you had an aluminum 5.3L, it was an L33. Apparently not? Did GM put out some aluminum 5.3L's at base HP levels? Is there any way to tell if the motor we have is actually an L33?
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Last edited by old motorhead; 02-02-2009 at 07:17 PM.
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Old 02-02-2009, 07:10 PM   #4
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I believe theyre the 799 heads from a quick google search. Could be wrong though.
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Old 02-02-2009, 07:39 PM   #5
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Quote:
Originally Posted by 00ChevyScott View Post
I believe theyre the 799 heads from a quick google search. Could be wrong though.
The #'s on the heads are 862. Not sure of much else...that I'm sure of.
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Old 02-02-2009, 09:45 PM   #6
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All the 862 and 706 heads we've ever seen were virtually identical in every way. Same valve sizes, port and chamber cores. You'll be fine with the 706's.

Good luck,

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Old 02-03-2009, 04:50 PM   #7
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All the 862 and 706 heads we've ever seen were virtually identical in every way. Same valve sizes, port and chamber cores. You'll be fine with the 706's.

Good luck,

Richard
Thanks Richard,

After further review, once we got them off and compared the two sets, they looked exactly the same. Guess I got some bad info. Maybe GM meant to say, " the L33 has LS6 "type" heads. I guess the compression bump was from the pistons. Still not sure if we have an actual L33 motor.
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Play: '08 Vette, LS3, TVS 2300, 219/231 w/115lsa cam, ported throttlebody, LT's, ZR1 clutch, Z06 differential, extremely quick.
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Old 02-03-2009, 04:57 PM   #8
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Thanks Richard,

After further review, once we got them off and compared the two sets, they looked exactly the same. Guess I got some bad info. Maybe GM meant to say, " the L33 has LS6 "type" heads. I guess the compression bump was from the pistons. Still not sure if we have an actual L33 motor.
If its aluminium 5.3, its an L33.
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Old 02-03-2009, 06:38 PM   #9
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If its aluminium 5.3, its an L33.
We assumed that. Swapped the cam from the aluminum block engine. Also used the heads from the alledged L33 since they were recently decked and pressure tested. Might not get the L33's 10:1 C/R, but we'll have the upgraded cam and valve springs. If the only thing we lose is a half point in compression ratio, we'll be OK.
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Old 02-03-2009, 07:00 PM   #10
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I have posted this info before but here is what I have found On the LS1Tech side and tweaked it a little...
http://www.ls1tech.com/forums/new-ls...casting-s.html

ALL Gen III heads are interchangable. How ever They need to be mached up with the proper engine combo to see any gains.


Here is a list of a few casting #'s:

933 97 aluminum perimeter bolt 5.7
806 97-98 aluminum perimeter bolt 5.7
853 99-00 aluminum center bolt 5.7
241 01-03 aluminum center bolt 5.7 (some late MY00 cars got 241 castings)
243 04 up LS6 aluminum center bolt 5.7 ***These castings were also used around 05 in truck applications***
862 99 and up 4.8-5.3 Truck heads
706 99 and up 4.8-5.3 Truck heads
799 05 and up 4.8-5.3Truck heads ***reportedly came on a few corvette's too*** These are basically 243 Heads
873 99-00 LQ4 6.0 Iron center bolt heads
317 01 and up LQ4 and LQ9 6.0 aluminum center bolt heads
035 01 - 04 LQ9 6.0 aluminum center bolt heads

Even more info:

Casting Numbers 241, 806, 853
Head: 1997+ LS1 5.7 Liter Passenger Car
Material: Aluminimum
Part Number:
12559806 (1997-98) Chambers = 69cc
12559853 (1999-00)
12564241 (2000-03)
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 Liter 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 and 862
Head: 1999+ LM4 4.8L / LM7 5.3 Liter Truck
Material: Aluminimum
Part Number:
12559862
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 873
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 Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Casting Number 317, 035
Head: 2001+ LQ4 and LQ9 6.0 Liter Truck
Material: Aluminimum
Part Number:
12562317 -LQ4
12572317 -LQ9
12572035 -LQ9
Combustion Chamber Volume: 71.06cc
Compression Ratio: 10:1 LQ9 Flat top pistons
Compression Ratio: 9.6:1 LQ4 Dish piston
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
Simple Milling Math:

You have a stock 66cc chamber and you want to get down to 63cc

66-63 = 3. You have to remove 3cc's

.007 x 3 = .021. So to get your 66cc chambers down to 63cc you'd have to mill ~.021.

You can also do the reverse, say you want to mill a head .030 to figure out how many CC's that removes you take .030 / .007 = ~ 4.28. Milling a stock 5.7 head .030 puts your chamber at ~ 62.



241 cast heads were Die Cast which is a process that smooths up the ports a bit compared to the Sand Cast procedure that was done on the 806 and 853 heads. Once ported any "advantage" the 241 cast had is moot.

Same Info goes for the 4.8L/5.3Ltruck 862 and 706 Head castings
While the 706 Heads are a SPM = Semi Permanent-mold And considerd to be a more consistant head casting then the 862 wich are Sand cast, Once ported There Is no difference.

--------------------------------------------------------------------------------
799 Vs. 243 Info Coppied From pillboxesghost Post's in ths thread http://www.ls1tech.com/forums/conver...l#post10241473

This appears to be one of the common misconceptions about heads having the 243 casting no. -- they are not necessarily LS6 head assemblies. The LS2 heads (243 or 799 casting) have the "heavy" standard LS1 valves. However, they do have the LS6 springs.

Only the true LS6 engine heads have stainless steel (not titanium) hollow stem valves (the exhaust stems are sodium filled). These valves are slightly longer that LS1 valves too.

The LS7 heads do have titanium valves.

New LS2 heads are about half the price of new LS6 heads (check sdparts.com). GM is "really proud" of those hollow stem valves!

Oh, if you have the 799 castings -- the only thing "Corvette" about them is the valve springs/retainers! Still a desirable set of LS1 heads though!

Supposedly, the 243 mold was done at GM Research, the 799 mold furnished to other vendors. The same vendor may have the 243 and 799 mold.

Both heads have identical sized intake and exhaust valves
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Old 02-03-2009, 07:00 PM
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