vacuum advance on marine motor

[proshadetree]

Re: vacuum advance on marine motor

In a controlled setup advance is set by ecu through the map o2 and tps Read by the crank/cam sensor.Vac advance in old dist was used to bump up the advance during acceleration.In a car it pulls harder.A boat cuts the water and then the boat catches up,kind of like your transmission slipping untill it locked up 1 to 1.A car has to work harder to get the rpms.I have used them in my younger years and like stated before it spark knocked.I swapped in a dual point no vac advance and it stopped.Ran a lot better.long story short.You are going to have x amount of advance regardless of advance type.30 degrees is 30 no matter how you got there.

 

[dan t.]

Re: vacuum advance on marine motor

ever notice what doesnt have vacuume advance
#1 race cars
#2 stationary engines such as welders or gen sets
#3 boats
its because they dont need them, vacuume advance is for economy under cruise,in some instances for emission controle,notably 70s era fords with dual diaphram setups, they were hooked to both venturi and manifold,venturi to advance manofold to retard under decel. air cooled volkswaggons used strictly vacuume,they had no mechanical
with present day electronic set ups all that stuff is obsolete, I work on this stuff every day and believe me I dont miss it

 

[bruceb58]

Re: vacuum advance on marine motor

Vac advances ADVANCE timing with application of throttle..

Wrong...put a vacuum gauge on an engine as you apply throttle and you will see the vacuum drop. You want a little less advance as you accelerate so to prevent the engine from pinging. With a vaccum advance, you get full advance at cruise as another poster indicated.

 

[system-f]

Re: vacuum advance on marine motor

you forgot that an auto distributor is not ignition protected or coast guard certified for marine use. So if you don't blow yourself up first, you will definitely get a ticket and be removed from use until you replace it the first time you are given a "courtesy inspection". the same goes for all fuel components, electrical components (starter, alternator, etc.), spark arrestor not air filter the list goes on auto parts are not designed for marine use. the only thing that is the exact same between auto and marine use is the block and internal parts except the cam and core plugs.

OMG , thanks for the warning but I was simply wondering WHY it wouldn't work...not that I was going to go do it and bypass all safety laws that may apply to my boat

ever notice what doesnt have vacuume advance
#1 race cars
#2 stationary engines such as welders or gen sets
#3 boats
its because they dont need them, vacuume advance is for economy under cruise,in some instances for emission controle,notably 70s era fords with dual diaphram setups, they were hooked to both venturi and manifold,venturi to advance manofold to retard under decel. air cooled volkswaggons used strictly vacuume,they had no mechanical
with present day electronic set ups all that stuff is obsolete, I work on this stuff every day and believe me I dont miss it

and here is the anwser to the question...because they don't need it not because it wouldn't work.

That's not how it works. The lack of vacuum retards the spark. For example, let's say you are climbing a hill and want to pass someone. If you accelerate and add more load to the engine, you may start having a ping if the ignition stays in its current advanced state. When you punch the accelerator you will immediately get a vacuum drop which will in turn retard your spark because less vacuum will be going to the distributor.

This amakes sense and jogs my memory..thanks. The old school auto distributors I remember had vacuum advance AND centrifugal advance.

 

[Friscoboater]

Re: vacuum advance on marine motor

I am more confused that when I started this thread.

 

[bruceb58]

Re: vacuum advance on marine motor

I am more confused that when I started this thread.

Then you are really confused since you didn't start the thread.