whats better J or X heads

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dazedand confused

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So is there a difference between the J heads and the X heads for a low buget performance build ??? I have a pair of J heads with 2.02 valves .
 
it may make a difference value wise for a '70 or earlier restoration.They will all support about 400 hp ..even the small 1.88 intake valve j heads and can be had quite cheap sometimes. Get
an economical valve job you can put together a nice street engine without much expense...and they
look so much nicer on a stock style muscle car.
 
I've seen a flow chart that shows the X head to outflow the J head and other factory heads. So X takes the win.
 
I would like to see a bonified flow test that shows a X head in original form that out flows a 2.02 J head?
 
Let's put it this way, I have heard of X and J heads on the same engine. There can't be that much difference in flow between the two.
 
My belief is the X is more $$ because:
The letter X itself id more "exotic" than the letter J...LOL
X came on pre emission 340's which carried a "pettigree" no mutts allowed
Mopar hoarders have squirreled them for so long they have become Folklore.
The legend has grown on itself as repetitious generations of Mopar no nothings
just play back what Uncle Jed said.
Go ahead and pay more for the golden X it doesn't matter how many tests have proven same as J ...Uncle Jed said.....
 
And how about the Z or O heads. They were the same as the J heads. But the U and some O heads were the 340 TA heads. Just a designation letter.
 
Let's put it this way, I have heard of X and J heads on the same engine. There can't be that much difference in flow between the two.
put a 2.02 X head on one bank, and a 302 head on the other bank.. that way you have the low end torque covered and the 6k rpm range covered. Talk about street and strip.... :D
 
put a 2.02 X head on one bank, and a 302 head on the other bank.. that way you have the low end torque covered and the 6k rpm range covered. Talk about street and strip.... :D
:rofl::rofl::rofl:
Don't say that. Someone will believe it.
 
Did not know that on the dimensions on the X heads . Ok well ill have to stick with these J heads since i bought them for $200. For the set with the 2.02 valves. Im going to have them milled down . I will be gasket matching the ports intake and exhaust . The valves will be cut back for flow and polished. Bowels cleaned up.
 
If a J head flows 250 cfm @ 400 lift.
and an X head flows 250 @ 400 lift.

Would it matter what letter is on the head?
 
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