Quote:
Originally Posted by Private_collector
I do have a gearbox mounted pump, but that mat not turn out to be usable, practical or indeed reliable.
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Oh ye of little faith! Have not these pumps proved themselves in wartime?!
Personally I'd sooner rely on a military spec blitz pump than a Taiwanese plastic one! Unlike electric pumps which can always burn out, they're extremely simple and robust. I doubt you could break one, even if you over-revved it. They can sound a bit rattly though, so you may want to rebush the conrod if it's a bit sloppy. You can even rebore the cylinder if necessary, I have some NOS pistons and piston pins, 20 thou oversize. Let me know if you need one and I'll stick it in the post. I haven't looked for new rings yet but they shouldn't be too hard to source. I'll start with motor mower shops!
The only criticism I've heard of these pumps is that they can empty the oil out of your gearbox. I don't really see how, unless perhaps they pressurize the gearbox somehow, eg. excessive blowby past badly worn rings. Like anything on a blitz, I take the view that if it's in good condition, it won't give trouble. Like I say, "proven in war". Not to mention sawmills!
I agree however that we do need 12V to run various accessories occasionally. But rather than convert the whole vehicle permanently to 12V, you can run the accessories off a converter, like the one in the pic below. More info here:
http://community.pressenter.net/~cmeyer/MES612PG6A.html
These gadgets only put out 6 amps, but if you need more you can easily hide a 12V battery somewhere, like in the tool box as you say. The converter will keep it charged as you drive. You can even run your electronic ignition off it, and probably get a few hours of 12 volt headlight use as well. If you want indefinite headlight use, just fit two converters! That will give you 144 watts of power without draining the battery.
You can also use the 12V battery as an emergency back up for starting the motor. You may need an isolation switch in the 6V charging circuit, so you don't burn out the genny and/or voltage regulator. And possibly an auxiliary 12V solenoid, just to be fully confident.
To me that's preferable to converting the whole vehicle permanently to 12V. In effect, you have a dual voltage blitz, and you avoid having to: a) rewind the genny armature and field coils and replace the voltage regulator, OR fit an alternator and figure out how to run a belt to it and relocate the twin-belt fan pulley and find suitable length belts to fit; and b) recalibrate all your gauges.
I believe the gauges do have to be recalibrated individually, because they all draw different currents, and the currents are all variable. Unlike a light globe which draws a constant current, you can't simply stick a resistor in series, you need a voltage regulator as well. I'm not sure it's something an auto elec normally does, I think it's more a specialist job for an instrument maker. I think they generally pull the gauge apart and solder an appropriate resistor in series, and a little solid state voltage regulator as well. There may be ways of doing it externally but it's still a specialist job. That is, if you want your instruments to read correctly and not burn out!
Others may have better advice than me on the pros and cons of 12V conversion, since I've never actually done it myself. I see it as something to avoid if possible. One thing I particularly like about 6V is the sound of a flathead cranking over on the starter. To me it's part of the charm of an old vehicle. With 12V they spin too fast, which makes them sound just like a modern car.