727 torque converter questions....

[ragtopfury]

I know the balancing differences between the 360 and other small blocks.....
My questions are:
Balancing aside, what years will interchange from small block to small block?
Will a small block 727 converter swap into a big block trans?
For a stock 383 magnum, would a 2500 or 2800 stall be better?
Thanks in advance for the info.....

 

[transman]

1967 to 1977 318-383-400 with a steel crank used a 12" converter no weights.
1972-1973 440 cast crank 12" with 2 weights
1972-1976 400 cast crank 12" with 2 weights
360 up to 1976 12" with 2 weights
The weights are welded on the back (mounting side) of the converter. All 12" converters used a narrow ring gear (about 1/2").

1972-1976 6cyl and 318 11" no weights wide ring gear (about 1").

Hemi and 340 had their own converters and at the shop I used to work at, custom builds only (cores are almost impossible to find for the hemi), and the 340 converter isn't all that common, but;
1969-73 340, 11" no weights, wide ring gear.
1973-1976 400-440 11", wide ring gear 2 weights.


On a stock 383, you might find that 25-2800 stall a bit loose. A lot depends on tire size and rear axle ratio. Lots to think about before you put a high stall in.
Looser ain't necessarily better.

 

[67Dart273]

I think he meant what will actually fit the trans. I don't know. You do have to watch for "lock up" transmissions. You can easily id these, they "extra stuff" on the valve body, and if you pull the converter, they have a sort of "pilot shaft" with a smooth area right at the front, like a 4 speed

The "non" lock ones have the splines cut right to the end of the shaft

 

[74Dusted]

Lock-up 727's appeared sometime around 1977. Non-Lockup 727's continued production as well. See 67Dart273's description on how to ID a Lockup 727.

Non-Lockup to Non-Lockup will swap, Small Block or Big Block.

If you use a "318" Converter behind a 440 (for example), The RPM it stalls at will be higher than it was when it was behind the 318.

 

[ragtopfury]

So would I be ok with a 2500 stall that was behind a 340 and put it in a 71 big block 727 - going behind a stock rebuild 69 383 Road Runner engine in my 68 B'cuda ragtop with 3.55's and 26-27 inch tire height? Opinions? Too loose? Will be a fun cruiser, not a race car.

 

[transman]

So would I be ok with a 2500 stall that was behind a 340 and put it in a 71 big block 727 - going behind a stock rebuild 69 383 Road Runner engine in my 68 B'cuda ragtop with 3.55's and 26-27 inch tire height? Opinions? Too loose? Will be a fun cruiser, not a race car.

The 383 puts out more torque than the 340, so the stall will probably be higher than 2500.
How much is difficult to say.
You need to remember that Chrysler supplied the 340 with a cast crank and the 383 with a steel crank. That issue needs to be taken care of to assure smooth operation.
What do you know about the 2500 stall converter? Is it new or used? If it's used it may or may not be the stall you think it is.

A quick calculation (thanks to Randy's Ring & Pinion) with your diff ratio and tire size(s) shows that at 60 MPH the engine rpm will be around 2700 RPM.

 

[74Dusted]

You need to remember that Chrysler supplied the 340 with a cast crank and the 383 with a steel crank.

Actually, the Cast 340 Crank was only from Late 1972 - 1973. 1968 - 1972 340's used Forged Neutral Balance Crankshafts. Making the External Balance/Cast Crank 340 pretty much a "1 year" only deal.

 

[transman]

Actually, the Cast 340 Crank was only from Late 1972 - 1973. 1968 - 1972 340's used Forged Neutral Balance Crankshafts. Making the External Balance/Cast Crank 340 pretty much a "1 year" only deal.

My goof. Didn't look far enough back.