Which flexplate for a 383/727?

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Reddartowner

Reddartowner

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Hi,

We're building up a mild 383 for my son's '68 Dart, which will have a 727 trans behind it. The 383 didn't come with a flexplate, so I don't know which one to get: one for 11 1/8 inch bolt circle convertor, or 10 inch bolt circle convertor.? We plan to run a stock/near stock convertor...

Help, please.......
 
Use the one that matches your converter. If it's a stock converter the 11" is correct. Anything else could be either a 10" or 11"
 
Well, we don't have a converter in hand. So as long as I match the flexplate to the converter the convertor bolt pattern doesn't matter in regard to engine ?
 
Right. If I'm not mistaken the 6 bolt crankshaft pattern was the same on all small and big block production engines so the only difference is the torque converter pattern. A lot of aftermarket flexplates are universal in that they have both the small and large torque converter pattern. The one I installed on my small block will fit a big block also with either the 10 or 11" torque converter.

BTW: what year is your 383?
 
I'm having the entire rotating assembly balanced by the shop... crank, rods, pistons, and balancer. So I guess that would make it internally balanced, right? I know there are internal balance and external balance converters, so I'd want one for internal balance...
 
There was only one flex plate used for the 383, and 440 ,They all came with 727, s.

There were TWO factory flexplates used on all Mopar (6 bolt) v8 engines from the late 60's to the early 70's. The 6 cylinder and hemi are different. Otherwise, you had either the 10 inch or the 11 inch. Big or small block, 727 or 904 made no difference. Although all big blocks had 727s, the 383s and 440's used BOTH flexplates. The stock 383 and 440 HP motors usually had a smaller converter that used the 10 inch while the bigger Chryslers with lower output had a larger lower stall converter which used the 11 inch. I've seen smallblocks with 904s and 727 using either one also.
flexplatediff.jpg
 
Cool, that helps a lot.... thanks. Can't seem to delete this picture I pasted in here.....
 

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Reddartowner said:
I'm having the entire rotating assembly balanced by the shop... crank, rods, pistons, and balancer. So I guess that would make it internally balanced, right? I know there are internal balance and external balance converters, so I'd want one for internal balance...
Click to expand...

Just because they balanced it doesn't make it internally balanced. It can go either way. Your best bet is to ask your machine shop to verify which it is.
 
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