mpaahana23
Well-Known Member
whats the difference between the j head and the x head????
I'm new
I'm new
which one get the 202 valves?The only difference is valve sizes on any of th 340-360 heads.
They are virtually identical other than valve size.
which one get the 202 valves?
X heads came with 2.02 and J heads for 70-71 340s had 2.02 valves ...all other J heads had 1.88 intake..
not sure about 1970...those could have been x or j but they were 2.02...
71 360s had J heads but they were 1.88
which one get the 202 valves?
If you are going to buy a fresh factory head with 1.88 or 2.02 valves, the 2.02 head will flow better. If you have a good 1.88 head and someone who knows what they are doing, putting in a 2.02 with proper throat and bowl work will way out perform a 2.02 from the factory whether ported or not.
For '70 models Xs were still common for 340s. All Xs had 2.02s- not the same as Js. Js were used on some '70 340s, on '71 340s and 360s- but with 2.02s in the 340s. '72 all Js were 1.88 intake. Technically the heads for '73 were not J heads- typically they have AIR holes that were blocked stock but the design's different than later heads. After June, a motor is most likely the next model year. Honestly Xs are a bit better, but with the big price difference your money's better spent in improving something else or stepping above stock. Otherwise- the 340/360 heads are all about the same- take your pick of what you can find, a more desirable casting cheaper means worth more when it's time to go. Some of the late '70s heads can be hard to give away machined- great when you're buying, awful when selling.X heads came with 2.02 and J heads for 70-71 340s had 2.02 valves ...all other J heads had 1.88 intake..
not sure about 1970...those could have been x or j but they were 2.02...
71 360s had J heads but they were 1.88
you guys know what the cc's of the j heads?
low compression ???I want to say 72cc, I believe.
you guys know what the cc's of the j heads?
U heads too.
thanksI'm a diehard fan of the 340/360 head! and with a little work you can make good ### BUT even i have fallen from the stock head. I went with a set of RHS head with my last build. I can make a 340/360 head flow as much or more then a RHS head prepped with a 2.02. BUT for the same flow (CFM) the rhs will outperform the stock head.(better port shape,(velocity) that you can't make without finding coolant passage or so close they crack)
The short answer........If you need to put guides in the heads, building ANYthing over stock. RHS iron heads is cheaper in the long run, and more power.