I'm making this a sticky, because
no bus should suffer a 009 longer than it has to.I've been badmouthing the 009 distributor for a while now, but just the other day I finally got my much ballyhooed AirCooled.net SVDA to slap on Geri Lou.
Man is it night and day! I am in no way associated with AirCooled.net, but you have to buy one! At least find a proper stock distributor.
After running the 009 for a year and switching to the SVDA, I noticed that she runs waaaaay smoother. Engine vibration is minimized, gas mileage is up, temps are down, lowend torque is there, idle is healthier, etc. Take it from a guy who lives and drives in the San Francisco hills, where lowend torque and gas mileage are quite important.
Just do it, you'll thank yourself later. It will pay for itself in gas savings alone, not to mention wear'n'tear.
How do I tell what dizzy I have?The 009 has only a condensor on the outside of it. And the numbers on the side are something like XXX-XXX-009.
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loginA Vac-Advance has a big vacuum pot on the side like this:
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loginWhat is the Difference Between a 009 and a Vacuum Advance Distributor?It is all in the advance mechanism.
Well, a 009 advances the spark by means of weights that spin outward through centrifugal force as engine RPMs increase.
This is an OK method in a light vehicle like a bug, that jumps right through the lower RPMs anyway. But in a heavy vehicle like a bus, it forces you to power through the low RPMs by filling the cylinders with fuel through the flooring of the accelerator. This wastes gas, causes increased wear, and rougher running, in addition to the flat spot in acceleration.
A Single Vacuum Dual Advance (SVDA) distributor advances the spark just like a 009 (it is basically a 009, with a vacuum pot added). But it is the vacuum can than makes it "special." You hook it into a vacuum port on the carb, which pulls vacuum from the time you first push the pedal until you reach half throttle. This causes the spark to advance as soon as you push the throttle, instead of waiting for RPMs to build.
How does this help? When you advance the spark in the lower RPMs and lower gears, you need to feed it less gas to get the same amount of power. Instead of making a bigger explosion in the cylinder to build power, you use pressure and time. The fuel combusts earlier, which, under full load conditions would cause detonation, but under light load conditions means that the combustion event has more time to build pressure in the cylinder. More pressure = more power. More power x less gas = more efficiency!
