Cylinder Head Information (GM)

Might be a repost, but here.



GM Head Guide

Casting Number 241
Head: 1997+ LS1 5.7 Litre Passenger Car
Material: Aluminimum
Part Number:
12558806 (1997-98)
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

Head: GMPP C5R
Material: Aluminimum
Part Number:
12480005
Combustion Chamber Volume: 38cc
Compression Ratio:
Intake Port Volume:
Exhaust Port Volume: 70cc

Head: GMPP C5R
Material: Aluminimum
Part Number:
12480025
Combustion Chamber Volume: 38cc
Compression Ratio:
Intake Port Volume:
Exhaust Port Volume: 70cc

Head: GMPP C5R
Material: Aluminimum
Part Number:
12480090
Combustion Chamber Volume: <30cc
Compression Ratio:
Intake Port Volume:
Exhaust Port Volume: 70cc

Head to Block Fitment

Because of their comparatively small bores - 3.89"-LS1 and LS engines can only use LS1, LS6 and LS2 heads. Using heads designed for larger engines will cause valve-to-block interference. The larger, 4.00-inch bore of the LS2 enables it to use LS1/LS6 heads, as well as L92-style heads (including LS3, LS9 and LSA). The 6.2L engines (LS3, L92, etc) can use all production heads except for the LS7, while the 7.0L LS7 and C5R blocks can use any LS Series head. LS7 blocks should be matched with heads designed for at least 4.10" bores; 4.125" bores are preferred.



Most LS production cylinder blocks share the same cylinder head bolt pattern and the same size head bolts-four 11mm bolts per cylinder (10 in total) and five upper, 8mm bolts. Early LS1 and LS6 engines used different length 11mm bolts, but engines from 2004 and later use the same length bolts. LS9 engines use stronger, 12mm head bolts.



Non-production blocks, such as the LSX and C5R, offer the same head bolt pattern as production blocks. All LS heads will bolt up to them, but care must be taken to select the most compatible heads based on the appropriate bore size. Because of their large bores, heads designed for at least 4.10" bores should be used and a 4.125" bore are preferred, such as the L92/LS3 or LS7 heads otherwise, calve-to-block interference is an issue, as is sufficient cylinder sealing.



GM Performance Parts new LSX cylinder heads use (10) 11mm and (13) 8mm head bolts, or eight more than a regular-production LS head. That's more than 50-percent more head bolts than production heads, offering a 21-percent increase in total clamping capability and 100-percent more clamping in the 12 o'clock and 6 o'clock positions, right where gaskets leak and blow out in power adder applications.

Gen III & Gen IV Small Blocks
Part Number Description Liters CID HP TQ Bore Stroke
19165628 LS327/327 5.3 327 327 347 3.780" 3.622"
17801267 LS1 5.7 346 350 365 3.898" 3.622"
17801268 LS6 5.7 346 405 395 3.898" 3.622"
19156262 LQ9 6.0 364 345 380 4.000" 3.622"
*19165484 LS2 6.0 364 400 400 4.000" 3.622"
*17802134 LS364/440 6.0 364 440 404 4.000" 3.622"
12611022 L99 6.2 376 430 424 4.065 3.622"
19171224 LS376/485 6.2 376 485 475 4.065" 3.622"
19171225 LS376/515 6.2 376 515 469 4.065" 3.622"
19201992 LS3 6.2 376 430 424 4.065" 3.622"
19211978 LSA 6.2 376 556 551 4.065" 3.622"
19201990 LS9 6.2 376 638 604 4.065" 3.622"
19171821 CT525 6.2 376 525 471 4.065" 3.622"
19165058 LS7 7.0 427 505 470 4.125" 4.000"

More information at:

LS General Charts

The only problem I see with this is that the compression is for the original motor....if peeps are looking to swap heads they may see this and think "oh tossing on these heads will give me xx.xx compression" when in all reality it will more than likely not be what is listed.

:lol:

Just giving you crap dude. Good post.

ehehehe nice TJ.. but let me ask, cuz im stoopid.
if i put 243s on an LQ9 with stock pistons, what compression ratio would that give you?

ok time to do the math.. you, GO!

Good repost, if it is one.

Anyone know what heads are compatible with what blocks (no modifications needed)

I've heard LS1 heads have to get machined before going on say a 5.3 block.


I want to get better heads when I put my headers on (heard too many stories about people breaking bolts off, would rather just swap out head and gain a few extra horse while I'm at it, then spend hours trying to drill/tap aluminum head)

updated

Good info tanz +1

Found a set of 799 heads on craigslist... those are same as 243's correct? They don't have rockers on them, what is a decent price to pay? I am planning on dropping them off at the machine shop before I install them/the cam.

I've seen them go for $500 most times if they are low mileage units, under 50k.

Any idea what a reputable shop would charge to machine them and do a 3 or 5 angle valve job and throw in a set of quality springs? I would like to get as much power as possible without going CRAZY.

You can buy a brand new set of 799 heads assembled for $319 each from sdparts.com or various other GM dealerships. I am just working on a lunati high-lift cam and valve springs. I think the springs that are good to .660 lift with locks seals and springs was around $300