x heads

[1970340t/a]

hey guys what is the difference between the 340 J heads and the x heads wich ones or better.....

[passing you]

They are the same except the factory x heads had 2.02 int valves while the J's didn't and only got 1.88 int.

I for one have both j's & x's and do notice more exhaust floor on the x's but it could simply be core/cast variance.

[Duder]

actually 70 Js casting number 3418915 has 2.02 valves also.

[1970340t/a]

so if i had a set of j heads with 2.02 int and a set of x heads there would be no difference

[passing you]

Originally Posted by Duder

actually 70 Js casting number 3418915 has 2.02 valves also.

Thanks ad.., I mean duder, I knew that'd draw you out.

[pcrmike]

I have a set of J heads with 2.02 valves, and a look in the throat shows no port work or blending that I can see, but no hardened seats either, so they are pounded in pretty good. I may be wrong, but sid the X head 915 come on the T/A and AAR 340 six pak? If so they had offset intake rockers and no pushrod pinch if I am correct. :-)PCRmike

[aarracer]

I don't believe any heads had the letters T/A cast into them, just the blocks and steering boxes. Both of my sets of T/A heads are "U" castings with casting #'s ending in "915"

[dgc333]

Originally Posted by pcrmike

I have a set of J heads with 2.02 valves, and a look in the throat shows no port work or blending that I can see, but no hardened seats either, so they are pounded in pretty good. I may be wrong, but sid the X head 915 come on the T/A and AAR 340 six pak? If so they had offset intake rockers and no pushrod pinch if I am correct. :-)PCRmike

The casting is the same between a T/A head and an X/J head. The T/A heads were machined for off set rockers which would allow you grind out the pinch during porting but the pinch was still there from the factory.

[DJM]

Originally Posted by passing you

They are the same except the factory x heads had 2.02 int valves while the J's didn't and only got 1.88 int.

I for one have both j's & x's and do notice more exhaust floor on the x's but it could simply be core/cast variance.

I have seen early J's thaat were intro'ed following the X heads with 2.02 intake valves (stock).

[pcrmike]

DGC, thanks for the update, as I had heard about the machining for offsets, but having not seen one personally, I was not sure on the pinch. Never saw a "U" head. :-)PCRMike

[70AARCuda]

the T/A heads are based on the J heads, which will include U heads also...I believe mine have a U on them...same basic heads as noted offsetted pushrods are the difference and require offsetted mechanically rocker arms..