1973 cj5

good morning, I just bought a 1973 cj5 with a straight six in it, I think it is a 258 4.2 but am not sure. Does anyone know how to tell for sure other than the engine codes themselves? Also I bought a new set of points but don't know where they should be set at if anyones knows anything please let me know
thanks
brad

 

I don't think there's any way to determine 232 vs. 258 without looking up the casting numbers.

 

The build date code on the engine will tell. Where to find them and how to read has been posted here ... http://www.earlycj5.com/forums/showthread.php?t=3278
Jim (jpflat2a) posted the pages from the parts manuals a while back, but I can't find them. The engine codes are in your FSM too.

 

The stroke on a 232 is 3.50in. On a 258 it's 3.895 in. I don't know if you can check this be removinging a plug and measuring the piston stroke.

 

Any seasoned Jeep mechanic can probably tell you the piston stroke length by listening to it run. Can you tell us what it sounds like?

 

On the passanger side of block is a pad stamped either with an E for a 232 or an A for a 258..