40hp hot air choke tube (F_R question)

[tx1961whaler]

Heh.
Finally get to ask a question rather than answer one.
I have a mostly 1969 40 HP Evinrude Frankenmotor.
The air tube for the hot air choke is long gone. Hasn't been on there for decades.

However--there is a port from the intake manifold that goes through the carb to the auto-choke assembly, which would then normally have the hot air tube attached that runs to the exhaust cover/heat exchanger.
Right now, that air tube connection on the choke assembly is open, and has been for quite awhile.

Is it best to plug this hole off at the choke, the carb (manifold) mounting plate, or leave it alone?
It would seem to be silly to block it off, since the hot air tube and heat exchanger were not blocked off on the other end to begin with.
I have the carb off right now (float came to pieces), so it's no extra work to fix things up.

 

[F_R]

Re: 40hp hot air choke tube (F_R question)

Leave it open. The air that flows through there is part of the total calibrated air/fuel mixture. If you block it, it will run rich.

How is the heat exchanger? If it is rotted/rusted out, it will blow exhaust out under the hood, making it run lousy. You can tell by the exhaust blowing out the fittings. Just block both of them if it is.

 

[tx1961whaler]

Re: 40hp hot air choke tube (F_R question)

THanks!
I'll keep it open like it has been.
The heat exchanger was in very good shape when I replaced the outer exhaust cover a couple of years back. Luckily it has the thick stainless inner liner. I have both of the heat exchanger ports blocked off already because if I didn't do it the mud daubers would.