J heads on a early 340?

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oliver

oliver

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I thought early 340's were supposed to be x heads? I just aquired this 340 for a project of mine, i was hoping for 2.02 inch x heads, but they are J heads on a 68 block. Chance that it has 2.02 intake valves in it? The motor is very original. Never been apart.

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I did notice that the stamped steel rockers on the right bank were assembled wrong, looks like the pushrods were wearing on the side of the heads and the rockers making side load on the valves... think i should fix it or yank the rockers and pushrods for an adjustable set of 273's?
 
given that the engine is 43 years old....you never know who or what has torn the engine about and put it back together...

there were J heads in 1970-71 that had 2.02 valves...
 
70aarcuda said:
given that the engine is 43 years old....you never know who or what has torn the engine about and put it back together...

there were J heads in 1970-71 that had 2.02 valves...
Click to expand...

915 J heads have the 202 intakes mine do.Still ya got a good runner there.
 
Hmm, any way to know if these heads came on the motor and if they have 2.02 valves? I've known the owners for my whole life, and i don't think they would lie about not ever having the engine apart. If they have the small valves, im probably going to tear the motor apart, if not i'll throw it in and run it as is.
 
66fs said:
It has been apart. It should have X heads. J heads had not been produced in 1968.
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Agreed! No 915 heads (J) untill 70. This motor would have originaly had X heads. Edelbrok performer intake , valve covers , and tci tranny are original to I sapose. Im pretty sure the factory didnt put the rockers in backwards. Its pretty obvious someone has been there playing around. After all it is over 40 years old.
 
casting date of 12/10/68 came in a 69 model... late 69 there is a possibility that that it came in an early 70 model as late as it is ive seen way stranger things come from ma mopar
 
If it's truly 40+ years since it's been apart...... YOU NEED TO REBUILD IT.

If it has had the head off..........you still need to take the heads off to evaluate a rebuild..............................................

Either way, you need to pull the head.

Taking a HUG risk just tossing it in your car.................................
 
could be a U head that is 2.02 valved, all you have to do is pull a valve cover and look for the 4 digit date code if it comes out around April 71 or before it should have 2.02's in it, anyway as old as these things are i would rather have a 1.88 head and stick a 2.02 in it so the valve is nice and high in the head as opposed to a 2.02 thats going to need its 4th valve job sinking it even more.........
 
Cudafever said:
If it's truly 40+ years since it's been apart...... YOU NEED TO REBUILD IT.

If it has had the head off..........you still need to take the heads off to evaluate a rebuild..............................................

Either way, you need to pull the head.

Taking a HUG risk just tossing it in your car.................................
Click to expand...

Drove the challenger here to pull the engine, we were banging 6200 rpm shifts with it, sounded okay. Either way, i'll probably pull it apart to see what it needs.
 
I checked the engine a bit more today, on the ID pad I get

EW340P2780069 Then a maltese cross, running vertically there is a 2Y211C

On the left cylinder head i get 3418915 C with a date code of 2540, J head
Right cylinder head 2531894-A date is 01189, X head.
 
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