Crankshaft with 8 holes for Fluid Drive coupling

[Bobacuda]

This projects just keeps providing new fun things. I got an engine from a '47 Dodge to rebuild to replace the messed up engine in my '53 Dodge truck (with Fluid Drive). The '47 had Fluid Drive. I took the two engines to the machine shop, where I noticed that the '47's crank has 4 holes and the '53's has eight holes. Needless to say, I told the machine shop I need the 8 hole crank from the '53 to mate it up to the Fluid Drive (BTW, the '47 Fluid Drive had 4 studs cut off to mate it).

Now I read somewhere that the 4 hole crank and the 8 hole crank use different length connecting rods. Is this true? I just need to know so I can tell the machine shop to use the '53's connecting rods before this thing gets bolted together. Any thing else the 8 hole crank would have different than the 4 hole crank I need to switch out?

Thanks.

[Young Ed]

4 hole and 8 hole only had different rods if one was a 218 and one a 230. Anyone know if you can just drill 4 more holes in the 4 holer?

[greg g]

I believe he fluid drive crank also has a little bit thicker flange. Is the Crank so far gone as to be unusable?? However you machinist could probably make the determination regarding if there is eough meat there to support the FD.. I believe the issus is the larger rotating mass needed the extra fasteners rather than the extra weight.