340 head examination

[challenged]

I was going to get a set of X heads for my 340 and I came across an interesting set of 3418915 J heads. The owner says they are 2.02 valved from the factory. I think he said they were from 70 or 71. There are not T/A heads and do not have the offset valvetrain. He says that when the factory ran out of X heads they installed the larger intake valves in some early J's and he has come across a few other sets. It is my understanding that a 2.02 J will flow identically to an X. I plan to do a mild port job. Has anyone else heard of these heads? Are they a good buy? Any insight would be appreciated.

[paul]

3418915 was used on the 1970 six pack in 1971 it was on the 360,and in 1972 it was used on the 340 and 360. The only diff. in the casting for the six pack was where the pushrod holes were drilled.

[DAVE JONES]

That funny you asked this question. I just picked up a set of these heads and am planning on redoing them. I have heard that these are identical to the X heads and the only difference is the markings, but these confirmations are from what I feel are unreliable sources. As far as the 1970 six pack usage, what exactly was different on these heads from the none six pack heads with the same casting number. knowing this group we will really find out what we have. come on guy....level with us...thanks..DAVE

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[340king]

The heads we have on the '70 Duster digger we run are 2.02" valved 360 heads. I don't have the casting numbers, but they are Z castings. I have only come accross one set of these in my life. They appear to be identical to the X castings in every way. I'll post the casting number when I work on the heads tomorrow.

[x-treme29]

According to Carroll Shelby's Speed Secrets (Mopar Engine) the head with casting #3418915 was used on the 70 340 6 barrell T/A, 71 360 and 72 340/360. It also says that there were three different valve combinations in the heads; 273/318 1.78 intake & 1.5 exhaust.
68-71 340 2.02 intake & 1.6 exhaust.
360 & 72-73 340 1.88 intake & 1.6 exhaust.
It also says that the early 340 casting number 2531894 is no longer available, instead the 360 head casting number 3418915 is used and finished machined to the 340 specs. The heads are identical to the early 340 heads in terms of port size and shape, valve sizes, and combustion chamber volume and are sold under the early 340 part number. It doesn't say what engine the machined 360 head was used on or what casting letter was used. Hope this wasn't to long of a post and hope that it helps some.

[340king]

The Z cast heads carry the casting number 3418915. I don't know what the letter designations all mean. The same casting number covers several original applications of both 340 and 360.