New Head On 1974 Amc 258?

The AMC 258 motor out of my CJ-5 is almost ready to be picked up from the machine shop, but I've hit a snag on the head.

When I went in to check on the progress, the machinist told me that he was having trouble finding new rocker arms, so we looked up the casting number (3222652-1). According to his reference book, the head belongs on the smaller displacement AMC 232 motor.

The history of this CJ-5 is unknown to me, and the head could have been replaced at some point. This site (AMC Head Casting Numbers | Gans's AMC Info) says it came with both. Not sure how to proceed.

 

Balderdash. There is zero difference between a 232 and 258 head from the same month/year. Only the stroke (and thereby the pistons and rods) is different 232 to 258.

There was some foolishness with stamped, then cast, then stamped rocker arms ca 72-73-74. Jeep changed from cast rocker arms to stamped rocker arms mid-1974.

I suspect he's reading the book wrong, looking up the casting number and getting an older part. Prior to '71, there was no 258, only the 199 and 232. The cast rocker is a 3223455, regardless of the number that is cast in. It may be true that the pre-71 232 was a 3222652, but you need a 3223455 if it's a cast rocker. The stamped rocker is 3223888. This is direct from the Jeep Corp parts counter book.

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Thanks for the good info, I purchased and installed new Melling MR812 rockers.