78 aspen, dont hate me if it's not a f-body
 

This is my first mopar. 78 aspen with a 73 340, 727, 2500 stall, 3.23 rear.
The 340 is in bad shape, at some point retaining rings were left out of #1, and #8 broke a rod, gouging the crap out of #7!
I have access to a late 70's 360 from a motor home.
From what I've read, both engines are externally balanced.
Can I use the stall convertor with the 360?

It depends if your 340 has a cast crank or not, your converter should have external balance weights on the engine side if it has a cast crank. The 360 is a cast crank and needs the external balance converter.

the 340 crank has the big balancer. it has a round flex plate with a small weight on the converter side. the converter doesn't have any weights. thats for your help

Do you have the motor out and can you post a picture of your converter?

"Balance" is a relative word. Magnum 360s are balanced differently than LA 360s. Both of those groups are balanced differently than cast crank 340s. In other words "they ain't the same."

LA 360s used weighted flywheels and torque converters, 340s do not, and the 340 balancers are different than are 360 balancers regardless of cast / forged crank in the case of the 340

So what do you do?

340 to 360..........

Use the correct 360 balancer

So far as the flywheel / converter, use the correct flywheel

Converter.......either use the correct converter, or buy an aftermarket weighted flex plate like BM. There used to be loose weights you could buy and weld to a neutral converter, to turn it into a "360 weighted" converter.

Sorry this is NOT correct. The 340 and 360 converters are not weighted the same

ALL LA 360's were cast crank !! Converter may or may not have weights ? If they are small weights they are probably to neutral balance the converter. The 360 weight is usually something like a larger 4-5 oz welded to the front side of the converter If in doubt check with the MFG

I stand corrected , it's been 30 years since my last 360 build but your correct the 360 converter is unique.

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Here are the pics I got. The weight on the flexplate is on the crank side. There is no weight on the convertor.
Thanks for all your help

For a hundred bucks at summit you can get the flexplate you need for a 360.

Is the B&M 10236 the one you mentioned?
Here is its description
Flexplate, External Engine Balance, 2-Piece Rear Main Seal, SFI 29.1, 6-Bolt, Chrysler, 360, 727, Each

I have used the 360 B&M flex plate Good product !!! Looks like someone took a big bite out of it...