Hunter 30 Engine Switch - Coupling Issues

[TradioShow]

I thank you for taking a look at this as I'm about to shoot myself.

I'm switching from a seized Yanmar to a Farymann. One of the many measurements I took was measuring the Farymann's drive coupling and comparing it to the Yanmar's. They seemed to be the same so I went along and started installing the new engine only to find out once I had the two couplings perfectly aligned/tuned that the new engine's coupling bolt pattern is about 3mm narrower than the coupling on the pro shaft side. So to say, the bolts opposite each other when looking at it straight on are 3mm too close.

I thought there was a standard here. What should I do? Should I try to fit the old Yanmar coupling on the Farymann? Do we know if these are compatible? I spent about three hours on the internet and still cannot figure it out.

Thanks guys.

 

[Bill Roosa]

If I'm understanding you correctly the radius of the two bolt holes from the shaft center is different by 3 millimeters.
I'm thinking that the coupler on the prop shaft is removable and you need to purchase the correct one.
This stuff happens a LOT when you start swapping motors. Yes there is a standard but it is a yanmar or farymann standard so when you mix and match you have to also match the coupler. The shaft diameter, bolt hole radius from the shaft and key width and depth all need to match.
Good luck

 

[kito]

I guess you need to find the correct prop shaft flange. I am sure I'll hear some "no-no's" but if you can't find the right flange and the prop flange pilot diameter fits correctly in the engine's pilot bore, what would be wrong with having a machine shop mill the holes. The good thing is prop flange has plenty meat on that side. Better yet, have them drill 4 new holes 45 degrees from the old ones. If I am reading you correctly, you are talking 3mm on the radius and 6mm on the diameter. Actually, increasing the prop flange bolt holes by 1/4" may do the trick. Just a last resort thought.

 

[TradioShow]

That's what I was thinking, Kito.

I guess I can just use a pulley puller to yank the flange/coupler off.