Engine numbers

I'm sorry I have a feeling this has been beat to death. Is there any way to decipher if the 258 in my 74 is the original motor for the rig? In other words are their numbers on the block that will tell me this? Nowhere on the block is there a tag (like the V8's) so I am not sure. The reason is I want to know what year motor I have for tune up purposes and if it is original to the Jeep. Tanx

 

look for a flat machined surface near the top of the block
passenger side, in between distributor and rear of block
looking for: 701-A-20 (example)
7 is the designator for 1974 btw

 

Hi all

Don't want to be a nuisance, but while we are at it, is there a place on the net that tells how to read engine number ???

My # is 910 A 12, so when was it built ??


Bob in Sherbrooke, province of Québec

 

no need to go anywhere else
this should help
S6 and V8

 

Thanks!

 

Thank you

I now know that my engine was built on October 12th 1976, making it probably the stock engine in my 1977 CJ-5



Bob in Sherbrooke, Province of Québec

 

So, 2nd question is there any way to determine if the motor is the original for the rig?

 

Only by inference. If you know the build date for your Jeep (ie from the yellow sticker on the dash), the engine build date should be from soon before that. There's no matching numbers or anything like that.

 

is there any where to find a list a F-head numbers by year anywhere??