340 j-heads question
Digital Knightmare
What is the difference between say a 340 j-head and a 360 head...i know
the j-head is a high performance head but i am not clear on why. I am
looking at buying a 340 right now that has one j-head and one 360
head....could there be any problems with the engine that might stem from
that? Thanks...
Matt
ROBERT RALL
It depends on the year the heads were cast. Early 360's had 2.02"I and
1.6"E valves. If this engine is complete and has been run by someone I
would think they had the sense to match the valve sizes.
I recently picked up a set of "j" heads, they are cast with 360 on
them. I also have a set of late model (89) 360 heads for my 318.
Compared to the early heads they seem to be a bit narrower at the intake
port, thats using a gasket to eye-ball them, no actual measurements were
made. The late 360 heads came stock with 1.88"I and 1.60"E valves. I
don't know if the runner volumes are different at this point, they
haven't been measured yet either, but will be soon.
I've read that really there isn't much difference in them other than
relocated pushrod holes on some heads,T/A heads, and all can be worked
to perform as good as the others.
In the January 1999 issue of High Performance Mopar they take a set of
late model 360 heads and work them to perform like 340 "X" heads.
Good luck.
> Matt
Travis and Cathy
No 360s ever came with 2.02 intakes, only 1.88s. Only 340s had 2.02s
and that was only until 71, 72-74s had 1.88s. All heads that came on
360s had 1.88 intakes and 1.60 exhausts. I beleive the J head was
esentially an X head with 1.88s. I beleive the only difference between
a J head and a normal 360 head was a slight difference in port flow. I
personnally have a set of J heads with 2.02s, but someone had them
installed.
Travis..
Gary and Ruthie Singer
used 360heads on the 360&340 casting#3418915 1.88I 1.60E They are the
same head,the port size is the same,the only diffrence is the valve
size.All you have to do is have the 360 head machined to the 2.02
valve.G.Singer
Digital Knightmare wrote:
>
> What is the difference between say a 340 j-head and a 360 head...i know
> the j-head is a high performance head but i am not clear on why. I am
> looking at buying a 340 right now that has one j-head and one 360
> head....could there be any problems with the engine that might stem from
> that? Thanks...
>
> Matt
wagonguy
Travis and Cathy wrote in message <36B5DB...@pacbell.net>...
>ROBERT RALL wrote:
>>
>> Digital Knightmare wrote:
>> >
>> > What is the difference between say a 340 j-head and a 360 head...i know
>> > the j-head is a high performance head but i am not clear on why. I am
>> > looking at buying a 340 right now that has one j-head and one 360
>> > head....could there be any problems with the engine that might stem
from
>> > that? Thanks...
>> >
I beg to differ, I just installed a set of J heads on my 360. They had the
original valves in them (2.02) and have a large 360 cast into them between
the rocker shaft bosses.
Doug
PISHTA
mean it came on a 360 ci engine. Heck, the 360 casting was on 340 engines a
year before the 360 was released! The AAWJ 360 casting was first used on the 70
T/A head (3418915). Subsequent 3418915 heads were all 1.88/1.60