HiPo C4 Torque Converter

[OldGuy]

Guys, I'm in the process of rebuilding my HiPo C4. The transmission currently has a rebuilt single-drain-plug converter in it which I'm going to replace during the rebuild. My question is: Was this transmission equipped originally with a single or double drain plug converter? When in time did Ford transition from the double to single drain plug unit?

My car serial number is 6S803 and was built in the November/December '65 time frame.

Any wisdom would be appreciated.

Thanks in advance for your reply.

Frank

[gt350hr]

  Single drain plug .  The original converter was ink stamped AJ ( on my car #477) Dual plugs were an '80s thing IIRC.

[6s1640]

Hi Randy,

IIRC, you have indicated the HiPo C4 also had a different converter from the LoPo.  Please tell me what makes a HiPo C4 converter when compared to a LoPo C4 converter.  I did not see Bob Mannel describe this piece as unique to the HiPo C4.  Can a LoPo converter be converted to a HiPo?

Thanks

Cory

[gt350hr]

   Cory ,
     There is ZERO external difference. The change was internal to allow about a 500 rpm higher stall so the HiPo would idle in gear with it's larger cam. It could have been a different fin angle ( most likely) or internal clearance modification. Yes the converter can be cut open and the stall altered. "Most" modifiers like to stamp or paint or both the converter. If you could talk them out of painting it  , adding the 1.25" tall AJ  to the flywheel side , could be a dead ringer. You want about 2,000 rpm stall max. I had a local guy that would do them for me but has since gone out of business. In WA state you "might " get Hans @ A1 transmission to do one for you without marking or painting it. He mainly does drag race converters but "might' do one "through" me.
There are many other converter modifiers that could be approached too.
   Randy

[OldGuy]

  Single drain plug .  The original converter was ink stamped AJ ( on my car #477) Dual plugs were an '80s thing IIRC.

Randy, I'm a bit confused by your chronology regarding the 2-plug version. I have an untouched '67 LoPo C4 that has 2 drain plugs. I also noticed in the factory 1966 Comet, Falcon, Fairlane and Mustang shop manual that in the "removal and installation" section (page 7-33) that it says in step #2 to "Remove the two converter drain plugs (Fig. 28). Drain the fluid from the converter. Install the two drain plugs."

Did Ford produce both the 2 plug and the single plug version at the same time?

Frank

[gt350hr]

    Now I'm confused! LOL. I have only seen the single plug version on early convertors. My original converter is in my '67 Ranchero and has one plug.  Knowing the "Ford way" there was a reason why two drains were ''spec'd". A two plug converter would have a different part number than a single plug.
   I'll see if I can do some research on the subject.
  Randy

[6s1640]

Hi Randy,

Will a two plug converters also required a two clearance hole flex plate?

Cory

[OldGuy]

Hi Randy,

Will a two plug converters also required a two clearance hole flex plate?

Cory

Cory, this isn't Randy speaking, but I DO know the answer to your question (for once) which is an unequivocal "yes".

Frank

[6s1640]

Hi Oldguy,  Good job.

I pulled up the Ford MPC and found that the HiPo C4 converter AJ was not serviced with a matching replacement, at least in 1975.  The service part was the LoPo converter, part number C6AZ-7902-M.

Take care

Cory

[gt350hr]

   Cory ,
     All flex plates should have two holes , one opposite of the other. It is no surprise that the AJ was not serviced by '75 an replaced by the low performance version. I think it actually happened in '68 as I tried to get one and it was "D99" then. I gave up and found later it was replaced by the normal 289 converter as you noted. The valve body was the next thing to go away and strangely the last to go was the C servo which was available in the late '70s. I bought at least ten of them back then. Still have one in use.
   Randy

[6s1640]

Hi Randy,

Lady luck has smiled on me today.  Turns out I own an AJ converter and did not even know it.  Thank you for your help.  Yahoooooo   

Also, this converter is a double plug/drain style.  It is attached to a skinny C servo HiPo C4 tranny making it a the later style.  I do not know its origin.  IIRC, it has a March 1966 casting codes.

Hope this helps.

Cory

[gt350hr]

   Perfect!