74DartSwinger360
The Brat Pack
Would 915s have a J on them?
J Heads?
- Thread starter 74DartSwinger360
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Yeah but with wheezer compression.....that aint what I said in the quote. lol
A 10.2:1 360 (same as the early 340) with all the 340 trimmings including heads and cam wouldda blasted 350 plus HP through them HP manifolds. The 340 wouldda been a distant memory.
OldmanRick
Well-Known Member
Bingo.............
Bulldozer
free ice cream sandwiches
nothing a little head change and a couple of pistons wont fix lol
74DartSwinger360
The Brat Pack
Yea it would have. Sorry I ment to quote Abodee
No problem....good discussion. Lets keep it goin. Maybe somebody that actually knows somethin will show up and tell us all how it really was. lol
74DartSwinger360
The Brat Pack
Stroker would the 915s have the J on them?
74DartSwinger360
The Brat Pack
Sound like a plan.
All of um I've ever seen in person did.....but I've seen some online that did not.
Bulldozer
free ice cream sandwiches
i ve sat and listened (only for a couple of minutes) to the all seeing and all knowing how the 340 production stopped and the 360 took over in 1973. in other words , they had no clue the 360 had already been in production for 2 years
Yes. Since the 340 was already in production, they were just coming out with the 360. So any updates to the heads were charged off to the 360 program as it was a "new" engine and they can write off tooling costs for new products for a tax break. Any tooling costs to "maintain" existing tooling for current production is not able to get tax write offs. So they made the changes to the heads that would fit both engines and charged it off to the 360 program. Then could make the new tools early and "pull ahead" the change a few months before the 360 was launched and put them on the 340's. They then put the cast in 360 on them as the new changes were paid for on the new 360 program.
The tax write offs give incentive to the auto companies to keep coming out with new products instead of maintaining the "same old, same old"...
74DartSwinger360
The Brat Pack
Ok I guess the only way to confirm is to pull the heads right?
74DartSwinger360
The Brat Pack
So the reason they stopped producing the 340s is for a tax right off?
I would assume so, yes.
74DartSwinger360
The Brat Pack
Alright I will see if I can get the head off tomorrow and snap some pics for you guys to look at.
I'm not sure of the reason for dropping the 340, but by '74 when it was dropped, high performance was pretty much a thing of the past.
OldmanRick
Well-Known Member
I always thought the reason to go with the 360 as a performance engine option was to make smog requirements and add a few cubes to keep the power up.
The "J" head is a 915 casting.
They may have a J, O, U, N or nothing at all on them. J is a generic term for the head.
They may have a J, O, U, N or nothing at all on them. J is a generic term for the head.
74DartSwinger360
The Brat Pack
Ok thanks
The 340 was strictly a performance motor, not a duel purpose motor like all other Mopar motors. Pretty much no need for it anymore. By the time it would have been detuned, and smogged, the 360 would out perform it.
No, the reason they came out with the 360 is to compensate for the new emissions that choked down the engines so they gave them bigger engines to compensate for the "parasitical loss" from the emissions.
Then they phased in the 360 and phased out the 340.
The 360 replaced the 340
the 400 replaced the 383
The 318 and 440 took one for the team and dealt with the losses.
The different letters were to keep track of the different molds in production. If they discover a problem/issue, they need to be able to trace it back to fix it.
FIRST I ever heard that. It makes perfect sense though.
74DartSwinger360
The Brat Pack
So they are all the same? As in valve sizes.
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