[Rovernet] Another set of rare bits required.

[Fletcher Millmore via Rovernet]

The bulb supplies the excitation current for the alt to start working, 
which is why it stops charging if the bulb goes. But, the bulb only 
blows if there is a bad diode in the alt, which causes voltage to go way 
high. The bulb gets real bright before it blows. So, the bulb is a sort 
of fuse - you have a defective but not totally fried alt.  Some systems 
(GM I think) use a resistor in parallel to the bulb to supply the 
current even if the bulb fails, but you lose the safety aspect. I had an 
Austin America with this problem (and no money for an alt), and as long 
as I kept it under 6000 rpm, the bulb - and the headlights - would be 
bright, over 6000 pop! Got really good at changing the bulb along the 
road in the dark.

Some alts will charge without the excitation current, as there is enough 
residual magnetism to get things started once the engine is going fast 
enough, after which it keeps charging even when the engine speed drops. 
We used to get that on Delco alts replacing other things (because we did 
not know how to wire it correctly)- once you punched it up to 3500 it 
would work and put the light out. All depends on the fine detail of the 
alt/reg circuitry.

If the bulb NEVER lights, even when you turn the key on, it or some 
wiring is dead. The alt should supply enough power at idle that the 
light does not come on with engine running, even with low battery.

FRM

On 5/22/2014 7:23 PM, GeffMcCarthy via Rovernet wrote:
> Re NADA fuel pipes:  I removed all the charcoal canisters and lines in my
> 3500S, but may reinstall to limit the fuel odor after every partial fill.
> Does the charcoal deteriorate?  Can it be restored or refilled?  Thanks.
> PS:  The SD1 which I acquired in LA made it to Portland with only 1 snag: an
> alternator fault traced to the small alternator wire.  The previous owner
> related that if the charging light bulb burns out, the alternator stops
> charging.  I have not seen the bulb lit, even with 9V on the battery.
> Interesting design fault, no?
> AvMedSafe
> Geoffrey W. McCarthy MD MBA DipAvMed
> 677 NW Melinda Ave Portland OR USA 97210
> 503-241-8468(h) 503-799-3809 (mobile)
>
> -----Original Message-----
> From: Rovernet [mailto:rovernet-bounces at rovernet.org] On Behalf Of Kent
> Kinard via Rovernet
> Sent: Thursday, May 22, 2014 1:14 PM
> To: Rovernet
> Subject: Re: [Rovernet] Another set of rare bits required.
>
> Yes.
>
> JULIAN BARNARD via Rovernet wrote:
>> Hi there - I am in the middle of restoring a1969 NADA Rover 3500S Auto.
>> Unfortunately the previous owner removed the fuel tanks and although the
> main fuel tank is easy enough to get in the UK, it seems impossible to find
> the Fuel Spill Return tank and associated fixings and pipework.
>> Has anybody in the Rovernet group got access to a set of parts such as
> these?
>> Julian Barnard.
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