New to 340 so I have questions
On '70 340s there are 4 other castings that are technically
correct, besides the 'X head. They are 0, U, Z and 'J castings
Some very late '70 340s got J' castings that have a 'U on the
underside, some also were 'J' all around, in very late 70 model
year.
The X symbol was added to the casting molds because the 340 heads were getting mixed up with the smaller valve 318 heads at the foundry. The X, J and O heads were simply different batch numbers of the same casting molds. I have a 1970 early build 340 and it has the O head designation heads. I also have a 1970 340 Dart Swinger and it has the J heads.
Here is a memo from the head foundry Engineer who called for the letter designation.
Contrary to popular belief, the X heads are nothing special and exactly the same as batches of J and O heads providing they had the 202 valves. Later on, the valves were reduced.
On '70 340s there are 4 other castings that are technically
correct, besides the 'X head. They are 0, U, Z and 'J castings
Some very late '70 340s got J' castings that have a 'U on the
underside, some also were 'J' all around, in very late 70 model
year.
The X symbol was added to the casting molds because the 340 heads were getting mixed up with the smaller valve 318 heads at the foundry. The X, J and O heads were simply different batch numbers of the same casting molds. I have a 1970 early build 340 and it has the O head designation heads. I also have a 1970 340 Dart Swinger and it has the J heads.
Here is a memo from the head foundry Engineer who called for the letter designation.