I've never seen a pre 64 401, but I understand that the crank shaft is designed only for a Dynaflow transmission. The question is . . . is it something that can be fixed with minor machining, or is it a big problem that will requre a different crank? And . . . it their anything else about a pre 64 engine that will make the use of a ST400 tranny impossible?
My dad and I did it over 20 years ago to our '63 Riv. We ground the end of the crank to fit the snout of the TH400 converter. It worked for many years until the engine let go and I replaced the crank with a 64. Scott
Jim, I took a 1959 401 and put it in a 64 lark with a 1966 th 400 the crank wouldnt fit the flex plate so i had the machine shop open the flex plate up to go over the crank flange. This did not make the eng out of balance. I raced it for several years and turned it up to 7000 on a regular basis. never had any problems with it. Doc
Doc, I checked with my dad, apparently we had the flexplate flamecut to a larger diameter to mate up as well. I have forgetten many of the details over the years.
I put a 4 speed behind my 63 401. The crank bolt pattern on the flywheel or flexplate is exactly the same as later cranks just the registering hole is larger on the 63 and earlier. I had a machine shop bore the brand new flywheel to the larger size for around $20 bucks. I made an adapter out of billit aluminum to press fit where the torque converter centered in the crank and use a standard pilot bearing. For someone using the th400 all that is needed is an adapter for the different size converter center register and a 64 and later starter to match the flexplate depth. I believe Carmon Fasco has the adapters you are looking for. I hope this helps, Jeff.
