Re: Vacuum advance

Steve,

Vacuum advance distributors are not used on marine engines because a marine engine is always under load. Vac advance is used to advance timing under no load or low load conditions in cars and trucks to improve fuel mileage and driveability. Intake vacuum will drop as engine load increases so the advance unit will not be working anyway, on the boat engine.
Someone probably removed the vac advance unit from your units.
I have never seen a marine version of the popular GM HEI distributor, others may have, but my impression of them is they are not normally a marine application. So be careful with the timing advance curve, some of them have a pretty health advance curve. Not necessarily right for a boat. Bill gives good advice on the max advance.

That distributor also may not have any spark protection, so keep that in mind. If there is ever a fire on a boat, with injuries, the lawyers have a habit of looking at non marine modifications to find a person at fault. This includes everyone who layed a hand on the boat in the past.

Hope this helps,
Greg