Re: Gearcase back fit
The motor you're looking at is a 90*, 20" V4 looper, nice motor. Any 20" V4 looper gearcase will work from any year. There are 2 styles on a V4 looper. One is the standard case with a 4 1/8" bullet with a 2:1 gear ratio. This case uses props in the 13 to 14" range.
The second is a case with a 4 5/8" bullet and a 2.27:1 gear ratio. This is commonly refered to as a V6 gearcase but it isn't. It is the same size as the V6 but a different ratio. But it uses V6 props in the 13 3/4" & up range. Most, but not all, of these were on 25" motors.
You can also use any V4 crossflow gearcase from 1979 & newer. You'll need a 90* V4 looper shift shaft.
You can also use any V6 gearcase, crossflow or looper, from 1979 & newer. The gear ratio will be different so you'll have to prop accordingly. The gear ratio is 1.85:1. Naturally a V6 style prop will be needed. Again you'll need the 90* V4 looper shift shaft.
I don't know why anyone would do this but it's possible -- any V8 gearcase will bolt up. That ratio is 1.75:1 and will use a V6 style prop.
