Converting a 6-Volt System to 12-Volts

You say it's a 1600 (originally 12 volts) which has been put in your car. So has the starter and flywheel been reconverted back to 6 volts? A 12 volt starter wont crank (or will do so only VERY slowly) on 6 volts, whereas the 6 volt starter sounds "normal" on 6 volts, (and very busy on 12 volts). The 6 volt starter can be left in the car during a 12 volt conversion, as it copes with 12 volts very well, and you don't have to grind out the bell housing for the bigger 12 volt flywheel; but in this case you are retro fitting a car to 6 volts, so the starter and the coil MUST be 6 volts. And the 6 volt starter means you HAVE to have the 109 tooth flywheel to match the starter (130 teeth on a 12 volt flywheel).

And yes -- the 6-volt system is fine with the 1600 engine -- you just have to have those matching 6 volt parts.

But because the 6 volts is now cranking a larger capacity engine, all connections HAVE to be good to ensure you don't short-change the starter, as it is a little less powerful than the 12 volt starter (.5hp in lieu of the 12 volters .7hp), and ANY voltage loss must be avoided.

So the battery ground strap, and the body-to-tranny strap must be in good clean condition, and the starter connections shiny bright too.

Is it possible that the coil is still a 12V unit?

If the coil IS a 12 volt coil -- you won't get enough of the 6 volts whilst cranking to fire the spark plugs (the voltage actually drops to under 6 volts whilst drawing out 60 80 amps for cranking the starter), but it might be providing marginally enough to fire the plugs once the engine is running and the generator is putting out it's 7+ volts. (This would cover the situation you say you have -- it starts on 12v but not on 6.) The coil should have the voltage written on the plastic end near the terminals.

There is a simple fix for a "hard starting" 6 volter, but you need to check all your connections first to determine whether it's just something simple, like poor connections or the incorrect starter and coil.

I remember having a Bug earlier (a '61 - '63 as I recall) that had very dim headlights. My '65 Bug was a vast improvement in that regard. In those days I wasn't smart enough to know the difference.

Interesting. It could just be that your earlier bug had poor connections and dimmer headlights, or maybe the later one had bigger (still 6v globes). My Dad's 60 had OK lights, definitely 6v, though I have no idea what wattage they were.

It would seem wiser to me to just buy a '67 or later with a 12v system in the first place, given the choice.

That's my thinking too. Both the cars I've looked at were advertised as �67, but turned out to be �66 models first registered in �67. Fun to have a drive though :-)

If I replace my voltage regulator (6 volts) how would I go about polarizing the system? Is it polarizing the generator instructions I would follow? Or completely different?

If I'm guessing right, you are replacing a 6v generator system with a 12v alternator. If that's correct, you DON'T need to polarise an alternator - they use a trigger current to start the process of charging - electromagnetism, so don't need any internal magnetism to begin with, like a generator does.

That trigger current is supplied via the alternator dash light (it's a tiny current and won't make the light glow when the engine is running) so if that bulb blows - the battery won't get charged and it will go flat. Curious circuitry VW used, but it works just fine. So that means that with an alternator equipped VW, you should always glance at the dash as you turn the key and make sure the Alt light does glow with just the key on, just to make sure that that circuit is intact.

I need to fit a 12-volt generator to my 6 volt motor. � The rest of the car is wired up as 12-volt, but I can run a 6v starter motor. Any ideas on a 12-volt genny?

If you mean an early 1200 with the built-in generator stand (the 36hp engine), I don't believe that you can fit the normal 12v generator to this stand, but you CAN fit an early Porsche 12v generator (which has the smaller diameter of the 6v VW generator) to it.

If you have the 1200 engine with the removable generator stand (the so-called 40 horse 1200), you should be able to fit the 12v generator stand to this engine and use the normal 12v generator (68 to 72 VW).

In fitting the 1200 engine to the later style gearbox, you may need to alter the throw-out bearing assembly to suit, as you would be using the early style 109 tooth (6v) flywheel to the engine (I presume). This will mean you have the 180mm (early style) clutch, which may not work with the "12v" throw-out bearing.

You can then use the 6 starter motor, and run it on 12v. It will last a long time so long as you don't crank for more than a few seconds at a time (it will heat up faster than a 12v starter would. It should not need to crank continuously anyway, since it will crank very fast compared to the 12v starter on 12v.

You have to use a flywheel which is compatible with the crankshaft. All 12v flywheels have a rubber "O" sealing ring, and some of the later 1200s use this too -- but the earlier 1200s use a paper gasket and you can NOT use this on a crankshaft designed for the O ring seal. Hope that makes sense.

Using a 6v starter on 12v is quite common with cars converted from 6 to 12v, since it means you don't have to change the flywheel to the larger 130 tooth 12v flywheel (which involves grinding the bell housing and fitting a new starter pinion bearing) - makes the conversion simpler.

Don't forget to use the 12v coil, and if you are using the early carby with a 6v choke coil - that will need changing to a 12 choke coil too.

The condenser is the same so it does not need changing.