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Engine 1980 CJ-5 Engine questions

Engine 1980 CJ-5 Engine questions

Jfox195

Jeeper
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Location
Seaville, NJ, USA
Vehicle(s)
1980 CJ5, 258
I have recently purchased a 1980 CJ5 . It has a 6 cylinder engine in it, with a 4 speed Transmission . Original plan was to swap engine out with a Chevy V~8
Time and money are now becoming a consideration as to which way we go with this. I have a few questions :
1. I have read that (or I think I have) the only engine that came in the 1980 CJ5 was the 4 cyl Iron Duke ?
2 So IF that is the case this was an engine swap, but I should assume that its a AMC 258 i6 / 4.2l ci ?
3 Has anyone reading this have any experience with engine builders / suppliers of mild high performance AMC 258 i6 / 4.2l ci Six cylinder engines ?

Thank you in advance for your replies. Im very new to Jeeps and look forward to working on this one.
Jeff
 
OK so after some consideration, I'm going to stick with the 6 that's in the Jeep. Hoping to find out if its original. I have read where the 1980 was a year of change from the heavy 6 to a lighter engine with aluminum intake, which this one has. My question is what number on the engine would say what year the engine is and where would it be located ? Thank you
 
Clean looking
 
OK so after some consideration, I'm going to stick with the 6 that's in the Jeep. Hoping to find out if its original. I have read where the 1980 was a year of change from the heavy 6 to a lighter engine with aluminum intake, which this one has. My question is what number on the engine would say what year the engine is and where would it be located ? Thank you
I believe the engine serial number is stamped on a machined surface located on the right hand (passenger) side between cylinders 2 and 3.
258_block_numbers_2.webp

I also believe the date is on the block on the driver's side near the front and a bit lower down than the serial number on the right side. The date code shows the day of the year as a 3-digit number (i.e. 055=55th day of the year) and then the 2-digit year itself. Here's an example showing "055 87" meaning the 55th day of the year in 1987. That would be Feb 24, 1987.
258_block_numbers.webp
 

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