Carb difference, long vs short shaft ?

[kjdunne]

I have a '89 40 hp evinrude long shaft, elec. start. My parts catalog lists different part #s for carb assemblies for short and long shaft motors. Are they interchangeable with minor modififications ie jets, linkage, etc. or are they completely different? Any advice greatly appreciated, I have a chance to buy a pair from a short shaft I would like as spares if they are compatable.

 

[wbeaton]

Re: Carb difference, long vs short shaft ?

Shouldn't be any difference. The long and short shaft makes no difference to the engine. Also, why would you need "spare" carbs. Carbs don't go bad. They may clog, but all that takes is a simple cleaning or at worst a cleaning and a rebuild kit ($20).

 

[kjdunne]

Re: Carb difference, long vs short shaft ?

I understand the rebuild process, guess I just want to start collecting parts for a 20+ year old motor I plan to keep.

Still don't understand the factory part # difference for carbs for short or long shaft motors. Could it be the difference in the exhaust housings affects the tuning that much?

 

[wbeaton]

Re: Carb difference, long vs short shaft ?

I don't know why they would be different carbs. The 5" midsection extension shouldn't effect the engine. However, I don't know why there are two separate numbers.

The part I don't understand is why you want two spare carbs. Its nice to have spare parts, but carbs don't go bad. I have never replaced an entire carb. Your money would be better spent on a spare lower unit or an entire parts motor than a pair of carbs. If you are dead set on buying a spare carb I suggest you just buy one since you'll likely never need it. Its your money. I'm just trying to help you save a little of it.

 

[kjdunne]

Re: Carb difference, long vs short shaft ?

Thanks Wayne, I see your logic. I'll let someone else buy them.

 

[jtexas]

Re: Carb difference, long vs short shaft ?

A lot of outboards have different carb specs for long/short shaft motors. I believe it's related to the difference in backpressure, but that's just a theory.

Parts motor isn't a bad idea, really, my motor just turned 30, and I've noticed "NLA" cropping up on the parts list (luckily nothing I've needed, knock on wood).