"Robert M. Gary" wrote in message
...
Reading my shop manual for my 4.3L 190hp carb'd Merc I see that it
describes setting the "base timing" as well as the "ignition timing".
Both procedures look almost the same so what is the difference?
Also, it says you must set the "Dwell" before timing the boat; what is
that?

The procedure for setting idle and mix on the carb is very complex in
the manual. They say you have to be in the water to do it. In old cars
I would just set the mix about one turn rich of when the car started
to run rough and I'd set the idle based on the tach. Why can't you do
the same on a boat?

-Robert

Dwell is measured with a dwell meter, and is more precise than setting the
point gap with a feeler gauge. Base timing is most likely with no advance
and Ignition timing is running at a certain rpm. You can check to see if
the advance weights or point base plate are stuck or the springs are bad by
checking timing at different RPM's. In the old days a lot of auto parts
house had distributor testers where you could check all the advance curves
with the distributor out of the engine.