how to tell the year of 4.2 -
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back > Models > Jeep CJ Forum > how to tell the year of 4.2

ROGUE FAB Tubing Bender with choice of 180 degree die set TeraFlex BIG Brake kit Jeep JK **Deals At Rockridge4wd.comBlack Friday and Cyber Monday Sales at

Unread 05-02-2010, 08:59 PM   #1
Registered User
Join Date: Apr 2010
Location: mercersburg
Posts: 10
how to tell the year of 4.2

recently bought a 4.2 for second jeep that i rebuilding how ever dont know if it is a earlier 70's motor or if it is a 80's motor/ because the size of main and rod bearings changes any input would greatly help... thanks you all...

Denver is offline   Reply With Quote Quick reply to this message
Unread 05-02-2010, 09:47 PM   #2
Registered User
1980 CJ7 
Join Date: Jul 2009
Location: NC
Posts: 256
post a pic, that will help for starters, and look for casting numbers.
EngChase is offline   Reply With Quote Quick reply to this message
Unread 05-02-2010, 11:20 PM   #3
Web Wheeler
Drednot's Avatar
1991 YJ Wrangler 
Join Date: Aug 2005
Location: phoenix, az
Posts: 2,594
Look for the numbers stamped on the pad between #2 and #3 sparkplug

then refer to this page to decode
91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35
12 Cherokee 4x4,3.7L,
"Non Vi Sed, Arte"
Drednot is offline   Reply With Quote Quick reply to this message

Quick Reply

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools

Suggested Threads

Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. is not in any way associated with Jeep or the Chrysler Corp.