Tuning Dynamo power at idle

[dangfiat]

Quick question all:

I have my idle set at ~1100 rpm, anything lower than that and the dynamo light comes on (around 1000rpm). Additionally, I have to bring it up to 1400rpm to get my timing light to put out enough light to time it (at 10degree BTDC right?)

So question: Is this normal or am I in need of a new belt or retention it (can I?)

Second question: Anyone in the US know of a fan belt I can pick up at the local stores? Ordering from UK for just a belt doesn't make shipping reasonable

Thanks!
Daniel

 

[lazylobster]

My car idle is 800rpm and no gen light on. I think your dynamo might be a little bit weak. Got a multimeter? You can test it.

This video is helpful



For the belt, any autoshop should be able to match it providing you tell them the width and circumference.

or, for US, these guys have it.

Fiat 500 Fan Belt - Engine - Fiat 500 - Fiat - Italian Cars

Fan belt for all Fiat 500 models. Beltis 9.5 x 813. Fiat part # 4156931 - 4335587 - 4434805.

mrfiat.com

 

[bugsymike]

Quick question all:

I have my idle set at ~1100 rpm, anything lower than that and the dynamo light comes on (around 1000rpm). Additionally, I have to bring it up to 1400rpm to get my timing light to put out enough light to time it (at 10degree BTDC right?)

So question: Is this normal or am I in need of a new belt or retention it (can I?)

Second question: Anyone in the US know of a fan belt I can pick up at the local stores? Ordering from UK for just a belt doesn't make shipping reasonable

Thanks!
Daniel

Assuming no other issues, faulty dynamo, non standard pulley diameters, faulty regulator unit etc. is the warning light bulb of the correct wattage. The reason I say this is an old school trick for slow running marine engines was to increase the warning light bulb wattage as this made the dynamo start working at lower revs I believe.
Re the timing light, assuming it is a powered version, try a separate battery supply as it may be due to your previous issue and too low voltage to make strobe light operate.
In the old days we used to set basic timing using a test lamp bulb or a volt meter at the points as very little mechanical advance below 1000 rpm. Also given the quality of fuel these days after setting basic timing on older vehicles a road test to check no sign of pinking/detonation when warm engine under load etc.

 

[Bounding Bambino]

The factory belt is a dayco 15315, gates 7315, which cross references to a 11A0800.

I went thru a bunch of belts till i found the perfect fit. Although i have an alternator instead of a dynamo. The pulleys and circumference should be the same. Also keep in mind the shims to set belt tension. IIRC the factory belt is 10mm wide, with the new modern one 11mm. But it fits perfectly. Might need to go a size up/down depending on alternator/dynamo shims.

 

[bugsymike]

Don't know about your specific Alternator fitting, but generally alternators run smaller pulleys than dynamos, so it may be worth checking what revs at idle the alternator is actually running at when compared with makers specifications.