Question on Heads
Thread Starter
Instructor
Joined: Mar 2002
Posts: 123
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From: Tekonsha Mi
Question on Heads
I have a set of heads I picked up somewhere with no info on them other than some numbers. Help? How can I find out more about them? They are supose to be stage 3 heads. There is a casting number in the corner 853 and another number below that of 0014100187429855. Any help or ideas Please?
Thanks
Thanks
Safety Car
Joined: Nov 2003
Posts: 4,979
Likes: 5
From: San Diego, CA "leaf" "tee" "e"
From http://www.mortec.com/castnum.htm
12558806...97-98...350..........Gen.III, "LS1", aluminum, 68cc
12559853...99-up...350..........Gen.III, "LS1", aluminum, 68cc
12559895...00-up...325..........Gen.III, Vortec 5.3L
12564241...00-up...350..........Gen.III, "LS1", aluminum, 68cc
12564243...02......350..........Gen.III, "LS6", aluminum
Just look at the last 3 numbers.
12558806...97-98...350..........Gen.III, "LS1", aluminum, 68cc
12559853...99-up...350..........Gen.III, "LS1", aluminum, 68cc
12559895...00-up...325..........Gen.III, Vortec 5.3L
12564241...00-up...350..........Gen.III, "LS1", aluminum, 68cc
12564243...02......350..........Gen.III, "LS6", aluminum
Just look at the last 3 numbers.
Burning Brakes
Joined: Nov 2003
Posts: 790
Likes: 7
From: Denton TX
Originally Posted by alleypatrat
I have a set of heads I picked up somewhere with no info on them other than some numbers. Help? How can I find out more about them? They are supose to be stage 3 heads. There is a casting number in the corner 853 and another number below that of 0014100187429855. Any help or ideas Please?
Thanks
Thanks
Part number 12559853 (casting number 853) is an LS-1 head. This particular casting comes in two forms. It was used in the 97 & 98 model years with perimeter bolt holes for the valve covers. In the 99 to 2000 model year this same head was used but the valve cover bolt holes were changed to a center configuration which also effects how the coil packs are mounted.
In 2001 GM started using casting number 241 on the LS-1 which is essentially the same head with a few "minor revisions," however my information does not indicate what those minor revisions were.
The 853 and the 241 casting use the following specs:
The chamber volume is: 66.67 cc
The Compression Ratio is 10.1 to 1
Intake port volume is: 200 cc
Exhaust port volume is: 70 cc
Intake valve Diameter is: 2.00 Inches
Exhaust valve diameter is: 1.55 inches
If you mill these heads .030 you will get a compression ratio of about 10.9 to 1.
Melting Slicks
Joined: Jun 2002
Posts: 2,246
Likes: 66
From: Middletown CT
Stage three usually, but not always, refers to the fact that the chamber diameter has been enlarged for use with larger than stock cylinder bore. I have been told that stage III heads can still be used on an engine with a stock bore, but you need to use the head gasket for the larger bore, or it won't seal properly.
