question on 340 to 360 swap
- Thread starter rscottick
- Start date
-
Locomotion
Well-Known Member
It depends on a lot of things, but off-hand, probably not.
All 360's are externally balanced from the factory. Balance is on the torque converter and balancer/damper.
Cast crank 340 are also externally balanced, on the torque converter and balancer/damper.
But there is more weight involved with the 360 so an OEM converter wouldn't be balanced correctly.
Same situation with forged crank 340's, which are internally balanced. No weight externally, but converter can't be swapped around.BUT if you do have a forged crank, internally balanced 340 with a neutral, no weight converter, you can simply use a B&M flexplate for an LA 360. It has a cresent cut out of it for proper counterweighting.
OEM flexplates are neutral balanced.
Other option is to find an OEM 360 specific converter. (non-lock-up)
ok s
Ok so the 360 im swapping in has the balancer and flexplate with it. Do I need to buy a new convertor to marry it to my 727 then?
Johnny Dart
Well-Known Member
Johnny Dart
Well-Known Member
Not sure what flexplate you have, but this is how I would go.
360 Harmonic Balancer.
B&M 360/727 Flexplate.
Neutral balanced torque converter. (no weights).
Keep it simple.
360 Harmonic Balancer.
B&M 360/727 Flexplate.
Neutral balanced torque converter. (no weights).
Keep it simple.
so can I use the flexplate that is currently on the 360, it is currently a 74 360 maited to a 904.Not sure what flexplate you have, but this is how I would go.
360 Harmonic Balancer.
B&M 360/727 Flexplate.
Neutral balanced torque converter. (no weights).
Keep it simple.
I am not sure if my 340/727 torque converter is nuetral or not. I dont remember seeing weights on it but its been a while.
Johnny Dart
Well-Known Member
That's a big "NO" on your 904 flexplate.
It has to be for a 727.
Read my post, and stick with it.
It has to be for a 727.
Read my post, and stick with it.
Locomotion
Well-Known Member
727 and 904 converters don't interchange.
If the converter bolt holes match up on the OEM plates & converter you will use, you can use the same one, but with a 360 LA 727 converter. (There were different bolt diameters and locations over the years. But I'm not familiar with the details. The B&M flexplates have the differences covered.)
If your 340 balancer/damper is flat, it's a forged crank and internally balanced. You can use a B&M LA 360 flexplate with your 340 converter.
If your 340 has a cast-in counterweighted ring on the balancer/damper that says "FOR 340 CAST CRANK ONLY", or something like that, it is externally balanced. You'll need a 360 specific 727 converter with neutral flexplate or a neutral 727 converter with a 360 LA specific flexplate.
If the converter bolt holes match up on the OEM plates & converter you will use, you can use the same one, but with a 360 LA 727 converter. (There were different bolt diameters and locations over the years. But I'm not familiar with the details. The B&M flexplates have the differences covered.)
If your 340 balancer/damper is flat, it's a forged crank and internally balanced. You can use a B&M LA 360 flexplate with your 340 converter.
If your 340 has a cast-in counterweighted ring on the balancer/damper that says "FOR 340 CAST CRANK ONLY", or something like that, it is externally balanced. You'll need a 360 specific 727 converter with neutral flexplate or a neutral 727 converter with a 360 LA specific flexplate.
-
