thanson_mopar
Well-Known Member
thats what i did with my heads, stock mid 70s 360 J heads. had some porting done, 2.02 intake valves replaced the stock 1.88 valves, bronze valve guides, comp springs.
340 Heads - Question
- Thread starter thanson_mopar
- Start date
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Jons340Dart
Well-Known Member
Ok Stupid question.
What's the difference between 'J' and 'X' heads?
What's the difference between 'J' and 'X' heads?
the X are suppose to always come with 2.02 intake and 1.60 ex valves.
J are not the larger 2.02 valves as a general rule, but they are out there in 2.02 on some years in the early 70s. They can be made into 2.02 style heads, ports are about the same give or take a small % in flow, and the cumbustion chambers are about 3-7 ccs larger in most heads I have checked.
BJR on the site is more of an expert on these things and I am sure hey can chime in with the specific details as can a few other folks. :drinkers:
J are not the larger 2.02 valves as a general rule, but they are out there in 2.02 on some years in the early 70s. They can be made into 2.02 style heads, ports are about the same give or take a small % in flow, and the cumbustion chambers are about 3-7 ccs larger in most heads I have checked.
BJR on the site is more of an expert on these things and I am sure hey can chime in with the specific details as can a few other folks. :drinkers:
66340SEDAN
FABO Member #3649
X-heads were the earlier big valve heads, they had a smoother runner, port casting (not larger), therefore they flow a little better in bone stock form. If you are doing any valve swap, or porting, save your $$$$ and buy the cheaper J heads or later year 360 heads! X-heads are for the "show car" , numbers matching crowd!!
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