LS1nterceptor

iTrader: (6)

I know this is probably been answered a hundred times, and I apologize for the FNG questions, but I was wondering if someone could give me a run down of all the heads in the LS family that will fit an LS1? I did try searching but I couldn't find a thread that answered all of my questions. I am having to try to sort out information and figure it out as I go and I want to make sure I've got it right. I have a stock 1998 Z28 and I am on a budget so I am trying to figure out what type of heads will and won't fit and what will and won't help me out, and why. I appreciate your patience and any information you can give me.

For starters, what casting are my factory '98 heads? They are either 853 or 241, correct? And they have 2.00" intake and 1.55" exhaust valves, right? What size combustion chambers do they have?

LS3/L92 heads will not fit due to the valve and bore size, correct?

From what I have gathered the 243 castings are LS6 heads. I understand that these heads offer a performance gain over my factory heads due to the smaller combustion chambers, and lighter weight hollow valve stems, correct? How much smaller are the LS6 chambers compared to the LS1? What size valves do they have?

And from what I can figure the 5.3L heads are either 852 or 706. And they have a significantly smaller combustion chamber than the LS1 heads. And I think they have smaller valves but I'm not sure. Is that right?

I haven't figured out what casting numbers the 6.0 heads are or how they differ from the LS1 heads, but I assume they have a larger combustion chamber. But I am sort of confused here, will the 6.0 heads bolt directly onto the LS1? Are the valves larger and does this create a problem with the bore? Can anyone tell me the 6.0 casting numbers so I will know them when I see them?

And 4.8L head won't fit at all, right?

I occasionally see 853 or 241 heads being sold after being ported but I don't really read about anyone on here running ported 853 or 241 heads, so that is kind of telling. Would a set of ported 853 or 241 heads be worth the effort of a head swap, or should I just look for some of the others listed?

I am looking for a set of budget heads that I can throw on in my garage without a lot of modification and I'm trying to decide between the LS6, the 5.3L, and the 6.0L(if they will fit) heads. I probably won't have them ported, just put some higher lift springs on them for a medium size street cam and an LS6 intake plus exhaust. And I will be naturally aspirated.

Thank you in advance for all your help. And feel free to throw in your advice on what heads would help me out the most and what is the best bang-for-the-buck.

djsanchez2

iTrader: (14)

Check the stickies man it's in there somewhere

Z28/2002

iTrader: (27)

https://ls1tech.com/forums/1740922-post41.html


Head Casting Info

ALL Gen III heads are interchangable.


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 LS6 aluminum center bolt 5.7
862 and 706 99 and up 4.8-5.3 truck heads
873 99-00 LQ4 6.0 iron center bolt heads
317 01 and up LQ4 6.0 aluminum center bolt heads
035 02 and up LQ9 6.0 aluminum center bolt heads

Even more info:

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

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 mille 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.

Sid447

Except for the "243" combustion chamber shape which was different to all other factory Gen 3 heads. This shape was found to be more resistant to detonation, and this kidney shape has been carried over & further developed in the Gen 4 heads.

CodeRed2000SS

these guys pretty much summed it up for you

LS1nterceptor

iTrader: (6)

Thank you, that was very informative and filled in some of the gaps I had.

TORCHD 02 TA

iTrader: (39)

good info there

philsblwnz28

iTrader: (10)

Would it be worth going from 853 casting to a 241 casting? What kind of gains would I be looking at? Motor still has stock LS1 intake and cam.....

Sid447

Have a read yourself here..

philsblwnz28

iTrader: (10)

Oh ok, so they both flow the same, and I would not be gaining anything by swapping to 241's. Correct?

SOMbitch

iTrader: (8)

The only difference is 241's are investment cast as opposed to the 853's being sand cast. It is a negligible difference if any at all.....

GMCtrk

iTrader: (23)

That is very interesting. My 317s I have sitting here have the LS1 shaped combustion chamber. It may be that way to achieve the bigger combustion chamber over the 243.