You really don't want to use an electronic rev limiter.
Have you ever been to the sprint car races? These guys use
the rev limiters and hit the limit on the straight-away. When
the rev limiter kicks in it makes the engine sound like it is
missing badly, because it is!
If you installed such a device on a rental houseboat all sorts of
bad things can happen. First off, the renter is going to push
the throttle wide open, no doubt about it. He may react to
the severe engine miss that results and call you up and tell you
that the boat isn't running right.
If he simply ignores it and leaves the throttle advanced to the
point that the rev limiter is activating then the engine is going
to be running very inefficiently. The carburetors will be
feeding the cylinders full air/fuel mixture but the ignition will
only ignite it occasionally. This will, as a minimum, be a
terrible waste of fuel and on a maximum it will fill the exhaust
with a combustible mixture so that when it does fire again the
resulting backfire can blow your entire exhaust system apart.
I would be a little worried about trying to restrict the throttle
via the linkage. Some mechanical type would figure that out
and also figure out how to circumvent it, perhaps in some less than
The restrictor plate under the carb sounds like the best solution
I thought of something tonight that may be something to think
A lawyer can make anything work for him/her. If you do something to
protect the customer and/or yourself and it doesn't work for some
reason,then your the loser. If you post a legible sign in plain
view that states the limits of allowable operation and the
renter exceeds that on his/her own choice then you are not
responsible.. Make sense?
If you buy a rental boat designed for a rental company they are
always 4 cyl underpowered units that would be hard to get in
trouble with but there are no modifications. It is just that
running full power can't get you in much trouble.
Boatless at the moment www.spboatsales.com