Posted By: Hardcharger65
340 O heads , what engine did they come on ??. - 10/23/08 11:42 PM
Id like to find out what year 340 engine O heads came on pn # 3418915 B, anyone have a clue ??, thanks Moparts.
340 O heads , what engine did they come on ??.
Posted By: RobX4406
Re: 340 O heads , what engine did they come on ??. - 10/23/08 11:52 PM
Those are the same as a J head.
Be the same years of production as a 915 J head, 1970-72
Be the same years of production as a 915 J head, 1970-72
Posted By: 340727dart
Re: 340 O heads , what engine did they come on ??. - 10/24/08 12:00 AM
Quote:
Those are the same as a J head.
Be the same years of production as a 915 J head, 1970-72
And, U and X, and whatever other letters may be on there.
Posted By: CJK440
Re: 340 O heads , what engine did they come on ??. - 10/24/08 12:24 AM
X's are a different casting number than the O,J,U 915 castings.
Posted By: Seth_Jones
Re: 340 O heads , what engine did they come on ??. - 10/24/08 12:46 PM
Do the '73 340 heads have any letter designation?
Posted By: MoparforLife
Re: 340 O heads , what engine did they come on ??. - 10/24/08 12:51 PM
Letter designation don't mean anything. Not even the J.
Posted By: wkroncke17
Re: 340 O heads , what engine did they come on ??. - 10/24/08 02:41 PM
Quote:
Letter designation don't mean anything. Not even the J.
Ive been told the X head is a better flowing head. It was built for the 2.02 intake, where as the rest of the heads were built with the 1.88 intake and they added the 2.02 later.
Again, this is what I was told by a very knowledgable friend of mine, just passing it on to you guys. If I'm wrong, or someone THINKS Im wrong - don't string me up for it!!
Posted By: ScottSmith_Harms
Re: 340 O heads , what engine did they come on ??. - 10/24/08 02:52 PM
There is allot of misinformation about early small block castings due to the various letters cast into them, it seems that people have a tendancy to believe that one letter or another offers something special....They didn't.
As mentioned, all 915 heads were the same castings regardless of the letter cast into them (BTW there were some with no letters at all). The "X" heads were a different casting number (ended in 894) but even those are nearly identical to 915 head castings, there's been allot of tests stacking one against the other, niether has ever been proven to be significantly better than the other (individual casting and valve job variables could easly erase any advantage by either).
If you want to buy a set of good early iron small block heads pick any of the above and go to a good machine shop, the end results will be the same no matter which cores they start with. If you want more bolt on HP simply buy a set of late model 308 castings, much better flowing head than any early head in stock form.
As mentioned, all 915 heads were the same castings regardless of the letter cast into them (BTW there were some with no letters at all). The "X" heads were a different casting number (ended in 894) but even those are nearly identical to 915 head castings, there's been allot of tests stacking one against the other, niether has ever been proven to be significantly better than the other (individual casting and valve job variables could easly erase any advantage by either).
If you want to buy a set of good early iron small block heads pick any of the above and go to a good machine shop, the end results will be the same no matter which cores they start with. If you want more bolt on HP simply buy a set of late model 308 castings, much better flowing head than any early head in stock form.
Posted By: AverageJoe
Re: 340 O heads , what engine did they come on ??. - 10/24/08 03:44 PM
I'm looking at buying a Dart - it has a 70 340 in it but has one X head and one U head - whassup with that and is it an issue ?
Posted By: ScottSmith_Harms
Re: 340 O heads , what engine did they come on ??. - 10/24/08 04:29 PM
Averagejoe,
Totally normal, the factory used what they had, many cars got two different letters, further evidence that there was no difference between them.
Totally normal, the factory used what they had, many cars got two different letters, further evidence that there was no difference between them.
Posted By: RobX4406
Re: 340 O heads , what engine did they come on ??. - 10/24/08 04:55 PM
Quote:
I'm looking at buying a Dart - it has a 70 340 in it but has one X head and one U head - whassup with that and is it an issue ?
Same here, got a 70 car with an X and an O head.
Posted By: CJK440
Re: 340 O heads , what engine did they come on ??. - 10/24/08 05:18 PM
Quote:Quote:
I'm looking at buying a Dart - it has a 70 340 in it but has one X head and one U head - whassup with that and is it an issue ?
Same here, got a 70 car with an X and an O head.
Thats the "hugs and kisses" 340.
Posted By: RobX4406
Re: 340 O heads , what engine did they come on ??. - 10/24/08 05:32 PM
Quote:Quote:Quote:
I'm looking at buying a Dart - it has a 70 340 in it but has one X head and one U head - whassup with that and is it an issue ?
Same here, got a 70 car with an X and an O head.
Thats the "hugs and kisses" 340.
Car hugged my cash as I kissed it goodbye!
Posted By: Rapid340
Re: 340 O heads , what engine did they come on ??. - 10/24/08 05:40 PM
Quote:
Thats the "hugs and kisses" 340.
I like that.
BTW, I had a 30K mi unrestored 70 340 duster with an O and U (Only this missing was the I).
It went to MI and the guy put two X's on it when he restored it.
Posted By: Rapid340
Re: 340 O heads , what engine did they come on ??. - 10/24/08 05:44 PM
Quote:
Same here, got a 70 car with an X and an O head.
--------------------------------------------------------------------------------
Thats the "hugs and kisses" 340.
Those came on pink cars and hit dealers lots in time for valentines day.
OK, I'm done
Posted By: fullonmopar
Re: 340 O heads , what engine did they come on ??. - 10/25/08 07:42 AM
Plenty 340s down under had 'Z' heads as well, so why is it 'J' heads get all the glory when as mentioned earlier that most of the heads are all the same.
Posted By: Hotwheelsjr
Re: 340 O heads , what engine did they come on ??. - 10/25/08 12:18 PM
Quote:Quote:
I'm looking at buying a Dart - it has a 70 340 in it but has one X head and one U head - whassup with that and is it an issue ?
Same here, got a 70 car with an X and an O head.
Ditto -- the 340 in my Demon has one X and one Z head. Both are 2.02/1.60 and were hogged out at the same time, so I have no reason to believe they didn't originally come from the same engine. In speaking with az_a12_bee, a friend of his bought a 70 340 Dart from the same guy I bought my heads from and he has indicated the numbers matching block in his Dart has different lettered heads also -- we assumed the previous owner may have had the two sets of heads off the original motors at one time and some how mix and matched them when they went back on the motors -- only diff is, the pair I have has had extensive port work and the pair he has are still stock. The original owner had physical control over all 4 heads until we bought our respective pairs. His came installed on his #s matching block and the pair I bought were not installed on anything at the time. Who knows...
Posted By: RebelDart
Re: 340 O heads , what engine did they come on ??. - 10/26/08 07:06 PM
Someone told me the U heads were six-pack heads ? Were 340 six-pack heads different ?
Posted By: RobX4406
Re: 340 O heads , what engine did they come on ??. - 10/26/08 07:17 PM
Quote:
Someone told me the U heads were six-pack heads ? Were 340 six-pack heads different ?
6 pack heads were different in that they had a different pushrod hole location.
I have a pair of U heads that are not 6 pack heads, standard pushrod location.
Posted By: MoparforLife
Re: 340 O heads , what engine did they come on ??. - 10/26/08 07:46 PM
Quote:Yes 6 pack heads are different but the letter don't have anything to do with it.
Someone told me the U heads were six-pack heads ? Were 340 six-pack heads different ?
Posted By: CJK440
Re: 340 O heads , what engine did they come on ??. - 10/27/08 01:24 PM
T/A heads are the same casting but just machined differently in the pushrod area.