Identifying your 4.2L engine

William Oliveri · 2004-02-21T22:23:39+00:00

Ok, this is what I found out in case anyone is interested.There are two main codes on a block that can help identify a 4.2L engine1st. ENGINE DAY BUILD CODE. This is located on the passenger side of theblock just below and between #3 and #2 spark plugs holes. It's a flat plateand has this format:The Engine Day Build Code consists of six characters: 1. Year built code 2 & 3. Number of the month 4. Engine size/type code 5 & 6. Day built Mine is 012C05 Which comes out to: 0=1980 or 1990 12=Dec C=2v carb 05=day of the month built See this site for more info: I was unclear on whether this would be a 1980 or 1990 engine. To narrowit down I located the Engine Serial number (2nd main code) which is locatedright behind the O2 Sensor on the Drivers side of the block. Mine reads: EF3235444 When I looked for this number on remanufactured engine sites I see thatthis block serial number started in 1981 through 1990. Therefore the best determination I can make is this engine is a 1990 madeengine. Hope this helps someone. Bill

Feb 21, 2004 Last reply: 3 years ago 23 Replies

Rate this thread:

Lee Ayrton 22 years ago

You are correct, I am wrong.

I could make an excuse of mentally tripping over "small block", but really I was just wrong.

I am still curious if it has a steel or plastic valve cover, though.

Vote

Jeepfam118 4 years ago

71-81 had the strongest castings for the block

Vote

Shawn 3 years ago

310cl06

Vote

Steve 3 years ago

Hey hope someone can help me my engine day built code is 006361 and my stamp on my engine is EF3235444. I have a 1978 CJ7. Looking for year of motor size and horse power.

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required