On Jun 13, 1:47 pm, "Robert M. Gary" wrote:
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

"The Cam angle, or dwell angle is the number of degrees through which
the distributor cam rotates while the breaker points are closed. It
is directly related to the breaker point gap. Decreasing the breaker
point gap will increase the cam angle. If the cam angle is too small,
the current will have insufficient time to pass though the primary
winding of the ignition coil, and a weaker spark will result. If the
cam angle is too great, the breaker points will not open far enough,
they will tend to stick together, and misfiring will result. The best
method of adjusting breaker points is by means of a dwell meter."

From http://www.pelicanparts.com/techarti...914_timing.htm

It has been a while since I messed with a dwell meter but if I recall
correctly the engine needs to be running, thus the need for the boat
to be in the water. It can be done with the boat out of water but
muffs would have to be used on the lower drive unit water intakes.