C6 Transmission - Torque Converter Question

[rbarkley]

I have an original  67 Shelby C6 trans that I purchased from Tim L for my GT500.

The transmission will be mounted to a 67 FE 427 MR Side Oiler.

What torque converter stall speed do you guys have or recommend?

Primarily street driven w/occasional strip.

I am not sure that a formula exists to determine this, but this is the info that is usually asked by those that make/sell converters ...

Car:
3:25 posi rear
Tires - Rear 235 60 15

Engine: 
C7AE-A/427-67 Side Oiler Block (Date 7C3)
C5AE-6090-F / 427-1965-67 427 Medium Riser Heads  (Date 7A5)
C5AE-C  427 Crank 427 High performance Forged Lemans (Date 2-67)
Rods - C6AE-E - Forged Lemans
2x4 Intake - C7AE 8525A Medium Riser
C5AF-9510-BC/Holley list 3301 - 1965-67 427 Ford 427 medium riser holley. Secondary card from 2 x 4V 
710 cfm each. No choke. Matching carb C5AF-9510-BD Holley list 3300 427 medium riser holley. Primary carb from 2 x 4V 
Dyno:
Max Torque 473 @ 4800RPM
Max HP 462 @ 6000 RPM
93 Octane Gas with 10:1 Compression

CAM:
Ford 352-428 Solid
Grind FE 272/282 -1OF
Duration @ 50   238  -   248
Separation   110
Duration @20  `272 - 282

I have had recommendations from 2200-2500 stall converter to 2500-3000 stall converter.

I believe that the usual 12" converter will not work, but possibly an 11"  or even 10".  I am concerned about the heat of running a 10" converter.

Anyone have any experience or recommendations using the smaller converter?
I talked with Performance Automatic, Broader and Summit.

Thank you!

Ron

[gt350hr]

    I would use a "converted" 11" from a C4. I say converted because the input spline is larger on the C6 and the pilot hub needs to be larger in diameter. By reducing the size of the convertor and because it is designed for a lesser torque engine the "stall" speed will be a bit higher without resorting to "typical" high stall modifications which hurt efficiency in most cases. Years ago I kept the 289 (C4) convertor when I added a stroked Windsor ( 408ci) to my '67 Ranchero. To me , the result was ideal. it would idle in gear despite a more radical cam and gets good mileage because it's "stock" internally.
   You don't need over 2,400-500 stall IMHO. Certainly not a 10" dia either.
    Randy

[Bob Gaines]

    I would use a "converted" 11" from a C4. I say converted because the input spline is larger on the C6 and the pilot hub needs to be larger in diameter. By reducing the size of the convertor and because it is designed for a lesser torque engine the "stall" speed will be a bit higher without resorting to "typical" high stall modifications which hurt efficiency in most cases. Years ago I kept the 289 (C4) convertor when I added a stroked Windsor ( 408ci) to my '67 Ranchero. To me , the result was ideal. it would idle in gear despite a more radical cam and gets good mileage because it's "stock" internally.
   You don't need over 2,400-500 stall IMHO. Certainly not a 10" dia either.
    Randy

Randy ,you continue to amaze me . 

[gt350hr]

   Thanks for the complement Bob. When I made the switch to the automatic car (477) , I had a steep learning curve on torque converters  when I switched it over to Boss 302 power. In '75  , torque converter modifications were becoming very scientific instead of "what we've always done". I was fortunate to become heavily involved in the evolution to the modern day racing torque converter . I learned about automatics the same way , out of necessity.
   Randy

[rbarkley]

Thanks Randy and Bob.

I think you are spot on.  It sounded as if the 10" would work for strip, but not so much for casual street driving or occasional cruises.
They do sell the 11" with the larger pilot and some have said that by reworking the original 12" TC that they can increase the stock 1848 stall to
2+.  I will check on the c4 TC mod that you mentioned as well.

I appreciate the reply!

Ron

[gt350hr]

   Ron ,
    We here in So Cal have several converter manufacturers to choose from. One I would trust for your application is Continental Torque Converters. Chris has a ton of experience ( 40+ years) in both all out race and street performance converters.  On the subject of the 10" converter , there are two basic "cores" companies use. One is from an early Falcon two speed and are the "tight" ( lower stall) ones as opposed to the  Pinto/351C  CJ  "loose" version.  They are easy to tell apart ( well for the trained eye) by the angle of the "bumps" or reliefs for internal fin attachment. The Falcon based cores have about a 25-30* angle on the bumps where the Pinto has an angle of about 45*s ( rough eyeball dimensions) the higher fin angle "confuses" the fluid more and creates a higher "stall" speed. Because of this it is less efficient ( fuel economy) that the Falcon bit requires less work to make a higher stall converter. Most companies use the Pinto cores these days for 10" Ford applications , small or big block. As an FYI "race" converters go as small as 7"s in diameter. And there are rumors of some smaller ones out there. I use an 8" , 5,000 stall unit in my '66 Hertz car.
    Randy

[rbarkley]

Thanks Randy.  Great info!  I think that I found a place more local.  Actually, just a few miles from where I grew up on the north side of Houston.
Brittain Part Service and they have been around since 1962.  Will keep you guys posted!

http://www.bpsconverters.com/