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Torque converter 340 engine - 73 cuda

Ralph

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How would I confirm that this is the high stall torque converter used in the 340 engine (2200-2500 stall). I found no numbers on it. It measures 10 3/4 " to outside of the mounting hole base plates and 10" to the center line of the flex plate bolt holes. The information I have on torqueflights is that this converter is supposed to be # 368 1052. It came out of the car when I rebuilt the trany but do not know if it is original to the car.
Thanks

73 Cuda torque conv 1.jpg


73 Cuda torque conv 2.jpg
 

704406

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In my experience the thicker ring gear and the overall smaller diameter of the converter usually means a higher stall speed original to the 340 and some 383 magnums. Is it original to your car? that's a hard question to answer, It came out of the car it could be.
I think a local trans shop if they have an older guy working there might be able to identify it.
 

Montclaire

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Wide ring gear = high stall. And the weights indicate a cast crank motor. You might be able to narrow down application by the thread size on the bolt holes. There were two sizes.

If you’re in the northeast and looking for a replacement shoot me a PM. I have a new 71-79 360 converter (essentially the same thing) from a project that I sold last year. I could have sold it five times over but the shipping on one of these things is astronomical. Photos posted for reference - model is a CR20.

8517B7B7-B2CE-4AB5-B9FA-DF7A905B7CD1.jpeg
068A9754-0CC1-4B48-BE1B-1FD44D70FF66.jpeg
 
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NoCar340

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A 360 has lot more external balance weight than a cast-crank 340. The cast-crank 340's harmonic balancer and torque converter (or flywheel, in the case of a manual transmission) are specific to that engine alone. The 340 balancer is clearly marked "USE WITH 340 CAST CRANK ONLY" but on the converter it's a different situation. Check out the differences in weight sizes between the two converters posted. A 340 would shake itself apart with a 360 converter installed, crank material be damned.

Based on experience with the differences in flywheels, I'd say Ralph's converter is a 340 cast-crank unit, but whether it's original to the car is impossible to say for sure.
 

Ralph

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Sounds like all these 10 3/4" diameter torque converters are high stall. Is that correct, if so I am good with what came out of the car and will reinstall it.
R
 

Ralph

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Montclaire thread size on bolt holes different.

Mine looks like fine thread - please advise thread size on different units.

Thanks
 

Montclaire

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I believe almost all were 5/16-24. My 73 Challenger had a factory hemi converter in it and I remember that taking a 7/16 bolt. Not sure what year the application was, I didn't build the trans. Come to think of it, I should have pulled that converter before I sold the car. I had bought it from a cousin of mine who had raced a max wedge plymouth from 68-72. At one point he had a full aluminum front end and some other parts, who knows what the history was on that converter.
 
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Montclaire

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A 360 has lot more external balance weight than a cast-crank 340. The cast-crank 340's harmonic balancer and torque converter (or flywheel, in the case of a manual transmission) are specific to that engine alone. The 340 balancer is clearly marked "USE WITH 340 CAST CRANK ONLY" but on the converter it's a different situation. Check out the differences in weight sizes between the two converters posted. A 340 would shake itself apart with a 360 converter installed, crank material be damned.

Based on experience with the differences in flywheels, I'd say Ralph's converter is a 340 cast-crank unit, but whether it's original to the car is impossible to say for sure.

That's the first I've heard that, and I've seen plenty of sellers listing the same converter for both. I do know that the weights are a little undersized from the factory 360 converter, maybe they split the difference? In any event, I have the converter for sale locally and have relisted it as 360 only. Thanks for the info
 

Montclaire

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6024318 is a 7/16” bolt. I think a lot of the aftermarket converters use a 7/16 lug, not sure of the thread count but if it’s the same the repop bolts have the thin head and would be useful.
 

NoCar340

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The 1972 parts catalog shows the following converter numbers:

318 w/904 trans: 2843586
318 w/727 trans: 2801762
340 forged crank: 2801764
340 cast crank: 3681641
360 (all 360s were cast crank): 3410918
400 forged crankshaft (1972 only): 2843586 (same as 318)
400 cast crankshaft: 3515282
400 w/four-barrel carb (HP): 3681145
440 std. perf: 2843586 (same as 318)
440 high perf: 3410839

Applications listed in italics are externally balanced. 1972 was the only year the 400 had a forged crank, and even then, not all of them did (4V and HP only). 440HP was exernal balance due to the Six Pack rods; it was still a forged crank. It's also worth mentioning that in later years, high-stall 11" converters and low-stall 10" converters both becamse available. High-stall converters during this era actually had a decal on them to identify them as such.

No matter; Raplh's converter has the cast 340 counterweights.


I do know that the weights are a little undersized from the factory 360 converter, maybe they split the difference? In any event, I have the converter for sale locally and have relisted it as 360 only. Thanks for the info
They're not a "little" undersized--the difference is enormous. There's no "splitting the difference" possible. The 360 uses nearly 5 times more external counterweight than the cast 340 on the flywheel alone. The 360 damper also has more counterweight than the cast 340's, hence the cast-in warning.

I'm not picking on you, Montclaire. I'm just trying to correct bad information and outright supposition regarding the balance issue. I don't want Ralph, you, or anyone else to destroy a freshly-built engine because "I heard it'll work" or someone told you it would.

Let's compare directly. The following information regards flywheels but the balance difference is exactly the same as it would be on a torque converter.

Here's the diagram for modifying a neutral balance flywheel for use with a cast-crank 340:

340castbalance.jpg



This is the diagram to do the same thing for a pre-Magnum 360:

360castbalance1.jpg


The drill bit required for the 360 is over half an inch larger in diameter, and three holes are required compared to the cast 340's much-smaller singular hole. The weight's distance from center has an effect, which is why it's stated in ounces per inch. It's also why the weight difference doesn't appear as drastic on the torque converters. You simply can't remove enough weight from a flywheel around the outside edge. Weights can be welded on wherever necessary as long as there's room.

If you take an externally-balanced converter, bolt the flex plate to it, and set it on its snout so you're looking at it from the engine side, the weights will be welded on 180° from where the holes are drilled in the above diagrams. Removing weight from one side has the same balancing effect as adding it to the other. B&M's 360 flexplate exploits this, and Chrysler used the same trick on later '70s 360 balancers: They have a large concentric groove in the weight opposite of where the counterweight was in '71-'72. Junkyard speed secret. 😁
 

Ralph

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Hey, thanks to all. This has been great information.

Ralph
 

Ralph

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What trany fluid are you using in these cars.

Last time I used dexron mercon which is hard to find.
 

gs73rallye

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Don't install that converter! The ring gear is badly worn. You will be pulling the trans to replace it soon if you don't replace it now.
 

Ralph

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So for those interested this is what I found. I have a warrantee block with numbers matching trany and rear end. The numbers on the trany rail identify it as the 10 3/4" high stall converter # 368 1052 (2200 - 2500 rpm). I believe that torque converter was original to the car. See the photos.

Thanks to all that assisted me !
 

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Steve340

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The ring gear teeth should be Ok so long as they are not chewed down to around less than 3/4 of their original length.
If they are OK get a die grinder and a little stone and just blend/polish that leading edge.
 

Ralph

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At this point the converter is in and works at least up on jack stands. Checking the fluid level and then will hit the street to see how it runs.

thanks to all
 
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