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moparjunkie

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hey guys simple ? 4 you whats the difference between x-j heads and what would u perfer?thanks happy holidays :drinkers:
 
moparjunkie said:
hey guys simple ? 4 you whats the difference between x-j heads and what would u perfer?thanks happy holidays :drinkers:
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Which engine?

Which x or j heads? Valve size?

I prefer # 302 heads, for the smaller swirl port chamber,
which bumps the compression ratio up too.;)

If on a 318 or larger, go for 1.88 intakes on the # 302 heads. :)
 
X heads came on 340's and had 2.02 diameter intake valves. J heads came on 340's or 360's and had either 2.02 or 1.88 intake valves.

All heads for 340/360 engines up through the late 80's had basically the same port size and shape and all have the same flow potential. The 2.02 valve size is only an advantage for an engine that will be turning rpm's in excess of 6000 on a regular basis. For a street motor you will have more low rpm power with the 1.88's. Any of the 340/360 heads can be machined to accept the 2.02 itake valve (the exhaust is 1.60 on all of them).

The 302's mentioned above are a 318 head that has a closed chamber and 318 size ports. These heads are refered to as a high swirl design.

The open chamber 340/360 (i.e., X or J) heads are not a good choice on a 318 unless work is down on the short block to raise the compression ratio. On a stock 318 it will make an already low compression ratio lower.
 
i have a 68 block with the x heads 202 valves so there open chambers heads with the x head with stock 202 valve and the j has 188 now our the stock flow # the same or is there a big difference?between the x-j thank you as youi can tell im an ex ford guy lol :notworth:

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Its best to state what you intend the heads for, the the cam and its specs,the max rpm,the hwhole nine yards so we can say what is best.On the out side looking in,we all might say head (A),but change a major factor and its now head (C),mrmopartech
 
Basically, they are the same heads. both work fine for a lot of engines. Both respond well to work..
 
thanks guys all these x-j w-2 man this is worst than dealing with all the alphabet cams with fords lol :drinkers:
 
Moparjunk, Moper is right. They are really the same casting. Different, valve sizes really only difference. Thay do respond well to port work. X heads are getting rare and will be more expensive, the 'J' castings are more plentiful as are the later years. If you have a set of anyone one of them and they are good solid cores, use 'em. Good luck, Terry.
 
They will have bigger valves and ports than the 318s. They also have 360 casted into the top of the port runner.


BJR Racing
 
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