258 Reman / DA07-DA08 Difference?

[ACGilley]

Howdy,

My son purchased a '76 CJ5 with a AMC 258 i6 / 4.2l / T-18 for his 16th birthday a few months ago and the motor let go resulting in a cracked block. After an exhaustive search and an unexpected education on the Jeep 258, I have learned the 75-79 258 (4.2) is a difficult motor to track down. We have Limited funds (laid off - oil industry) and the current newly transitioned boat anchor has some nice accessory items (intake/carb/header/ignition) so we are not interested in changing the setup as it was.

My uneducated question I am interested to learn is what the difference is between the 72-74 (DA07) 258 and the 75-79 (DA08) 258. I have done a little cross reference and know the header/intake/ignition all appear to cross over but I am unsure if there is some significant issue I should be aware of that would be a reason not to.

I have found several 72-74 (DA07) reman motors but not a single 75-79 (DA08) seems to be available (reasonably priced). I am looking locally (surrounding areas) on CL for a motor for sale but so far unsuccessful. Just interested to know from those that do what the difference is and if it would work as an alternative.

Thanks in advance for your help!

 

[HackFabrication]

First off: Welcome to the Forum!!!

Second: I'm of little help, the AMC 258 i6 / 4.2l block was cracked in my 76 CJ5 (which also had the optional T-18 ) when I got it, so I drank some Jeep KoolAid and dropped a Ford 5.0L in along with a Ford T18.

Just a WAG, but I'm assuming the differences have to do with emissions. Your accessories should all bolt on to a fresh long block. And it should bolt to your existing motor mounts. I'd recommend putting some new ones in, along with a new Transmission mount. Years of oil/crud have probably buggered up the originals.

On a side note: The 76-77 year CJ's have a number of unique parts to them. Don't be in a hurry to toss things in the trash thinking you can replace them with aftermarket items. Most are made for the 78-86 year models.

If you need any more info, you've come to the right forum!

 

[Lumpy Grits]

Welcome to the forum!
I would call these folks and see what they have.
J&W Auto Wreckers: New & Used Jeep Parts - Home

LG

 

[quinletc]

Welcome. I also have a 76 CJ5 , but mine has the AMC 232 i6 .

First, are you SURE you have a AMC 258 i6 / 4.2l ? When I bought mine, I was told it was a 258, but it turned out to be a 232.

Second, I don't know the difference between the two engines you mentioned, but you may be able to expand your pool of potential matches if you include 232 blocks.

I will defer to others with more knowledge, but I believe all you'd need is the crankshaft, rods, and pistons from the old engine, and a donor 232 would become your new 258.

 

[CDT540]

First thing I would do is make sure I know exactly what I have by using the attached casting table. The block casting number is located on the driver's side up front. The biggest difference I am aware of is from 80 to 81 where the head bolts went 1/2 inch to 7/16 and I believe a lighter crank and different intake and exhaust manifolds. The reference numbers you are using (DA07) are ATK part numbers and I don't believe will be of any value except when dealing with ATK. For whatever it is worth I have a mix, a '79 block with an '83 head. Hope this helps...

View attachment Block Casting Table.pdf