C4 big bell/small bell differences

Discussion in 'Technical' started by Grabber5.0, Jul 19, 2004.

  1. Grabber5.0

    Grabber5.0 Gear-head wannabe

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    I discovered this recently when switching from a big bell to a small bell C4, and wondered if anybody else has encountered this. The big bellhousing doesn't just have the starter moved over to accomodate the larger flexplate. It's also about 5/16" deeper than the small bellhousing. The torque converter is also the same hair longer.

    I had a stall converter made up for my new engine, and got my old tranny rebuilt and had the bell from a 74 Maverick put on it. When I finally got everything bolted together, the motor would not turn so I could put the last three converter bolts on. I double, triple, etc. checked that the converter was seated all the way in the transmission. I checked the converter in my current tranny, and it 1" back from the front edge of the bellhousing. When I seated the stall converter in the same tranny, with the big bell, it also sat back 1" from the bellhousing. The stall converter only sat 3/4" back from the front edge of the small bellhousing on the new tranny. With only 3/4" spacing, by the time the bellhousing drew up to the block, there was too much pressure on everything for me to rotate the crank with my ratchet.
    I have searched and searched, and found virtually nothing on this subject on the net. I did run across one tech site that mentioned it, and another site for some guy that sells converters. That site listed a bunch of different part#'s for the various incarnations of the C4 bellhousing from various years, along with some specs, including the depths. There were at least 5 or 6 different depths! I am sure there is some leeway in the tolerances, but how could you ever get the right converter if you were ordering one?!! Here is the link to that site: http://mmerlinn.bravehost.com/trans/fdc4f/Fd9c4bhd.htm
  2. dmhines

    dmhines Dixie Maverick Boy

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    I had a 73 that was originally a 3 on the tree and I converted it to a C4. I have no idea what the tranny was out of ... I just picked it up at a transmission shop. I ordered a torque converter from GER and installed it. Even with it properly seated I couldn't even get the bell housing to meet the block. Returned to GER and they sent a different one ... still had a problem fitting it. I finally talked to a tech guy at GER and explained what was going on ... he figured out what I needed and sent the correct converter and it went right in. Sorry I have no part numbers or anything like that but had a similar experience a long time ago ...
  3. Grabber5.0

    Grabber5.0 Gear-head wannabe

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    I meant to say that I was taking my converter back to the shop that built it so they can fix it. Apparently they looked it up wrong before, but now they know what I need.
  4. don graham

    don graham Member

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    when you order the convertor from a catalog such as summit, they list the years of the tranny plus the size of the flex plate. my original one was for a big bellhousing. when i switched to the smaller bellhousing i had to order another. in 1970 they changed from a 24 to a 26 spline input shaft in the tranny. when i changed to a 74 c-4 i again had to order another convertor. it all depends on the year of the tranny.:slap:
  5. MavKatrina

    MavKatrina Member

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