First sorry for the multiple boat question but 3 of us are performing
tune-ups, sharing the work. All 3 boats have new plugs, wires, caps and
rotors. Last weekend we set the timing per the spec on the engine data
labels while idling in neutral.

My boat (twin 1988 Mercuiser 350's, Alpha 1 drives) indicates on the engine
information that the timing should be set to 8 deg. BTDC.

I am now led to believe that the boat should be idling in gear (at what
speed) and the timing set (to the 8 deg. BTDC?)
The same info would be appreciated for the other 2 boats:


1. Twin 1990 Crusader 350 inboards, straight drives.
2. Twin 1986 Mercruser 454's, inboard V-drives

Does anyone know anything about this?

Thanks in advance for the help.

The idle speed should be adjusted with the engine in gear. You should get the
spec. on this but it is typically around 650 to 700 rpm. The timing should
then be adjusted. The only reason for setting the timing with the engine in
gear is so that if the engine speed increases as the timing is adjusted, the
speed can be reset and the timing verified.

If the engine speed increases to the point that the centrifugal advance kicks
in, the timing adjustment will not be valid. This is the reason for making
sure that the idle speed and timing are concurrently correct.

Bob wrote:

First sorry for the multiple boat question but 3 of us are performing
tune-ups, sharing the work. All 3 boats have new plugs, wires, caps and
rotors. Last weekend we set the timing per the spec on the engine data
labels while idling in neutral.

My boat (twin 1988 Mercuiser 350's, Alpha 1 drives) indicates on the engine
information that the timing should be set to 8 deg. BTDC.

I am now led to believe that the boat should be idling in gear (at what
speed) and the timing set (to the 8 deg. BTDC?)
The same info would be appreciated for the other 2 boats:

1. Twin 1990 Crusader 350 inboards, straight drives.
2. Twin 1986 Mercruser 454's, inboard V-drives

Does anyone know anything about this?

Thanks in advance for the help.