I've got an '87 YJ out in the yard. It has a rebuilt 4.2 engine in it, #212C21, which tells me it came off the line on Dec 21, 1972. Here's my problem. I want to put a new valve cover gasket on it, so I bought one for a '72 Wrangler. Doesn't fit. Since the 4.2, as far as I know, didn't go into Jeeps until 79(?), this must have come out of a Gremlin, Matador or another long forgotten AMC of the time. How can I find out which one and get the right gasket? Sure, I can cut my own, and I might, but I sure would be nice to know where the thing started its life in case I find any other small differences.
and it could be a 82... and I am pretty sure it is a 82
The engine Build Date Code is located on a machine surface on the right side of the cylinder block between the # 2 and # 3 cylinders. The numbers of the code identify the year, month and day that the engine was build.
Explanation Engine Build Date Code
Example: 3 10 C 11
1st Number Character is the build year: 3 = 1983, 4 = 1984
2nd and 3rd Number Characters is the build month: 01 = January, 12 = December
4th Letter Character code indicates the engine: C = 258 CID / 2v Carburetor / 9.2:1 Compression Ratio
5th and 6th Number Characters is the build day: 01, 02, 03 up to 31.
The example code 3 10 C 11 translate to: 258 CID (4.2 Liter) engine with 2V Carburetor and a 9.2:1 Compression Ratio, built on October 11, 1983.
Leaking, yes. That's why I want rid of it. That's why I pulled it. I'm really in the process of putting in a new distributor, but I'm doing a few other things along the way. Before I go any further I want to make absolutely certain what engine I'm dealing with. The code on the block identifies it as clearly a 4.2. The problems with the valve cover gasket are weird. It was reputedly rebuilt with a larger cam, but I can't see that changing anything else.
So what you think? 4.0 or 4.2 cylinder head?
Last edited by jcrocket13; 07-15-2015 at 08:58 AM..