1970 “J” heads

[B3422w5]

Was on a thread on facebook forum guys were talking about the different 340 head offerings.
To set the record straight, Mopar did put 2.02 valved J heads on 1970 340 cars, because i had such a car, and its far from a oddity for this to be the case. Know of others.
My matching numbers 70 340 Duster (B3) had 54000 miles on it when i got it. Ultra original other than a 4 or 5 year old “ outside” paint on it. By that i mean underhood, trunk, jams, etc were still original paint, rest had been redone.
Factory air still blew cold, and when i got around( ultimately) to pulling the heads off, they had the original head gaskets yet. Motor had never been out of the car.
Heads were 2.02 J heads. wish i could remember when the car was built(99% sure it was June 70) but i wont swear to it
I know the current owner and can have him look at the sheet if i needed to.

 

[pauly]

Sure there were 2.02 J heads. Was someone on here questioning that? My 340 has 2.02 J heads-not sure if they were originally or were upgraded at some point.

 

[B3422w5]

Sure there were 2.02 J heads. Was someone on here questioning that? My 340 has 2.02 J heads-not sure if they were originally or were upgraded at some point.

Guys didnt think they were available on 1970 cars. That was my point. Guys know they were on 71’s and 72’s.
I looked for old threads and one from here i saw rumblefish said J heads were not on 70 340 cars. Old, old thread
Just wanted to clear it up, seen it first hand

 

[Alaskan_TA]

Last full model year for X heads was 1969.

Leftover X heads were used at random during the 1970 model year. though.

J, O, U & Z casings letters can all be '915' castings (last three digits of the casting number) and they can be large valve or small valve heads depending on how they were machined.

I'll leave this here, again.....

 

[B3422w5]

1970 340 with "J" heads?? - Moparchat - Home of MOPAR enthusiasts worldwide!

That old thread was Moparchat, not this forum

 

[go-fish]

I have a 73 340 with 925 heads, one is O and one Z. Would these be 2.02 intakes? Or was it a crapshoot?

I also have 925 castings with no letters on them and they are 1.88. These came off a 73 truck 360. I was thinking having these ported, VJ, and putting in bigger valves if I get a little more serious with the 340 down the road.

I know it may cost as much as aluminum heads but there’s still a place for iron heads.

 

[rumblefish360]

I looked for old threads and one from here i saw rumblefish said J heads were not on 70 340 cars. Old, old thread

And then we learn things!

 

[B3422w5]

And then we learn things!

your humble, thats why i love ya !!

 

[RustyRatRod]

Yeah they made big valve J heads.....not as many as the X heads but they did make some.

 

[TT5.9mag]

your humble, thats why i love ya !!

Humblefish?

 

[rumblefish360]

your humble, thats why i love ya !!

Humble but opinionated… LOL
(Oh, part smart *** but not normally on purpose.)

Humblefish?

LMAO!

Better than Grumblefish….

 

[go-fish]

Better than Grumblefish….

When you drink do you turn into Stumblefish?

 

[TT5.9mag]

When you drop tools are you fumblefish?

 

[TT5.9mag]

When you can’t find the words are you mumblefish?

 

[TT5.9mag]

When you trip and fall are you stumblefish?

 

[Ironracer]

Yeah they made big valve J heads.....not as many as the X heads but they did make some.

I have a set on my 340, came off a 360, not sure what year block that was, or if they were original

 

[sireland67]

Yeah they made big valve J heads.....not as many as the X heads but they did make some.

Yes not some J heads, they must have made quite a few, I have had 4 sets of J's over the years and all had 2.02 valves.
In fact I still have two sets.
I removed a set off 71 360 cop car that got wrecked, yup 2.02 heads, the top end cost me $50 back around 1980, I was a dumb *** because for an extra $100 I could of had the bottom end and trans out of the car.
X heads, still have a few. The 70 cuda' rust bucket I just tore apart has a set, and it had never been apart, I know the history on that junk.

 

[B3422w5]

Yes not some J heads, they must have made quite a few, I have had 4 sets of J's over the years and all had 2.02 valves.
In fact I still have two sets.
I removed a set off 71 360 cop car that got wrecked, yup 2.02 heads, the top end cost me $50 back around 1980, I was a dumb *** because for an extra $100 I could of had the bottom end and trans out of the car.
X heads, still have a few. The 70 cuda' rust bucket I just tore apart has a set, and it had never been apart, I know the history on that junk.

the point of my post wasnt that 2.02 J heads were rare, its that they were used in the 70 model year.
Many equate them to just newer stuff than 70

 

[sireland67]

the point of my post wasnt that 2.02 J heads were rare, its that they were used in the 70 model year.
Many equate them to just newer stuff than 70

I have never pulled a set of J off a 70, but have seen X heads on a 71.
I guess its the factory using parts up.

 

[Jeff Seighman]

My numbers matching 1970 340 Dart came with J heads, it now has LAX heads, the Js are in the attic. Or are they U heads?

 

[rumblefish360]

When you drink do you turn into Stumblefish?

Actually people love talking to me when I’m REALLY TANKED because they say I have a funny slur.

I think it is closer to bejumbled-fish

When you drop tools are you fumblefish?

Yup!

When you can’t find the words are you mumblefish?

Yep!

When you trip and fall are you stumblefish?

Yep! And I end up as a Jumbledfish!

I just don’t like being drumblefish (inactive or sluggish) because it will turn me into a crumblefish (mindset)

1970 340 with "J" heads?? - Moparchat - Home of MOPAR enthusiasts worldwide!

That old thread was Moparchat, not this forum

Holy Moly!

 

[70dart340]

Since Rob has been kind to me and my family, I'm sending him a set of 915 "Z" heads from my collection. These are real, no photoshop BS involved.

 

[Oldmanmopar]

don't go by the letter. but by the last 3 of the casting number. 894 or 915. If you look at a set of J's? They are usually U's cut off by the spark plug hole.

894 202 valves in 68-69-70 are 10.5 compression. with 9.56 deck

915 202 valves in 70-71 10.3 compression . with 9.56 deck

Cut a set of 915's and you have 10.5 on 70-71 piston engine

915 188 valve heads came on 72 8.5 compression with 9.56 deck

 

[go-fish]

What would be done to a 8.5 compression 915 to optimize it say with a 73 340 piston? Of course racing valve job, and porting would be nice. What about milling and upsized valves?

 

[Oldmanmopar]

188 valves are all you need with a closed factory exhaust. Raising the compression would be the better choice. Have the heads milled a little and install thinner head gaskets, Don't over cam the Engine.

I always think back to early years of street racing these cars when they were new in the 70's. Two friends had 340 4 speed cars. One was a 69 swinger with 391's and the other was a 72 Demon with 355's. They would drag race all the time. They were dead even up until 4th gear and then the swinger would show the torque due to the HP and 391 gears the car could reach Max RPM's

Now you have to remember the swinger had a 309 first gear trans and the Demon had the better 247 close ratio trans. Swinger had a smaller Tire.

What I am saying is it was the combination in stock form the 72 cars just worked on the street. They would hook up and go they didn't put on a show. when those 68 69 cars were spinning the the 72-73 cars were able to put every bit of power to the ground. This was on the street with street tires. At the track it was a different story. 9-1 is a good street compression for today's fuel.