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Old 06-14-2015, 03:45 PM   #8
FirstNation
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Join Date: Sep 2011
Location: Fairport NY
Posts: 63
Re: GMC engine identification

Quote:
Originally Posted by dwcsr View Post
The problem is that they never used a B in a serial number. It was A then C skipping B

GMC engine numbers will often, but not always, begin with a letter which denotes the bore and crank journals other than "standard" and then three numbers for the engine size, which in your case would normally be a GMC 228.

Sooo....

If no code letter then the engine bore and crank is standard. IF it has a letter, the following apply:
LETTER..........Cylinder Bore Crankshaft Journals
...............................Main.......Rod
A .............+0.005".....-0.010"....-0.010"
B .............+0.005".....Standard...Standard
C .............+0.005".....-0.010".....Standard
D..............+0.005"......Standard...-0.010"
E............Standard......-0.010".....Standard
F............Standard......-0.010".....-0.010"
G............Standard......Standard...-0.010"
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