Alternator upgrade

[Gadge]

I have a niggling issue on my BIS motor. For those not in the know, there is a little lever on the back of the carb that operates a fast idle mechinism so when the cooling fan cuts in a little solenoid opens a vacuum valve that pulls on the said lever making the revs rise whilst the fan is in motion. Well I have long since lost that little lever - not even sure how but it's not there - so now when the fan cuts in the revs drop right down. When the lights are on it almost cuts out so to get round this I have to set the idle higher than I would like. Finding a new lever and pin are up there with chickens teeth and rocking horse poo so I was wondering if fitting an alternator with a higher output would help? Or maybe fitting a smaller pulley to the one I have would make it spin faster at low revs thus creating more power at lower revs? Electrics aren't my forte as such do has anyone got any thoughts on this?

[thepuddlejumper]

Gadge, not sure about this but if I remember correctly on highly tuned engines that rev considerable higher they change the pulley to stop the battery cooking, well I think that's what I read.

Ralph

[Gadge]

Hi Ralph, You mean fit a bigger one to make it turn slower?

[thepuddlejumper]

Gadge, yes, don't know if this would work in reverse. Would you need to upgrade the battery to cope with a larger capacity alternator?

Ralph

[thepuddlejumper]

Gadge, found this site, it may be of use.

http://www.onallcylinders.com/2015/03/27/alt-text-5-things-you-should-know-before-using-a-high-output-alternator/

Ralph

[Gadge]

Fantastic stuff Ralph! so going on that link I don't need a higher out put alternator as it wouldn't make any difference. The only electrical upgrades I have are the fuel pump and a slightly more powerful stereo - oh and I've upgraded my bulbs to halogen ones. Perhaps a slightly smaller pulley would help? I basically need to get the alternator to spin at the RPM that it's at currently when the engine is at around 700rpm.

[Pete126]

Hi Gadge, the only solution to your problem is to repair or replace the carb changing pulley sizes, alternator etc will not make any difference

[Xylaquin]

You could upgrade to LED lights to mitigate the drain when you switch them on.

But more effectively, can you find the part number of the lever in the electric part catalog (subscriber section)

[Gadge]

Yeah I did think of LED bulbs but a lot of the current gets absorbed by the ballast resistor in side/dipped beam system (the little coil in the luggage compartment) so may not do much. They will help however I just didn't want a mixture of filament and LED bulbs on the car.

I doubt fiat will be stock that little lever even if I did get the part number (I also need the plug that holds it to the carb) making one maybe the way forward or perhaps a new or completely different carb altogether.

[Xylaquin]

I doubt fiat will be stock that little lever even if I did get the part number (I also need the plug that holds it to the carb) making one maybe the way forward or perhaps a new or completely different carb altogether.

Ha no, not Fiat. But if you get the part numbers and search for them on https://en.partacus.de you might be pleasantly surprised.

[Gadge]

Wow that's a handy site  problem is I can't find a part number in the workshop manual

[Xylaquin]

any luck here? (click on the images to see corresponding part numbers)
http://club126uk.co.uk/subscribersgroup/BISEPC/EPC7/index.html

[Bambino126]

I seem to remember reading that the standard fan draws something like 30 Amps or something crazy, anyway when the fan cuts in that current is then demanded from the alternator to recover it. The alternator puts the strain on the belt which is driven from the engine so it slows down the engine. The load from the fan is a fixed load so changing to a different alternator would not change things. Changing to a fan with a lower current demand would mean your rpm's don't drop as much, but surely the right course of action for you is to find the right carburetor parts to fix the problem.
I thought you had a couple of spare webers you could pinch the bits from? If not they come up on Ebay from time to time.

[Gadge]

Your right about the fan bambino. The fan I'm currently using is a low amp fan aftermarket one and really does make a difference (I've compared the two and the drain between the standard an the aftermarket one is quite significant).

I did have a handful of carbs - polish and webers - but alas I sold most and the spare one doesn't have the lever why I kept it instead of the complete polish one is a mystery which I'll never solve. Making a new lever is well within my capability but the plug to hold it is a different matter. I wish I had a lathe

So, back to the alternator. I now see that a more powerful alternator won't work - the load will always be the same no matter what. Now I'm wondering if the solution to the load on the engine is to increase the revs (make the alternator spin faster or increase the hp of the engine to overcome it) then how about altering the size of the pulley? A smaller pulley would spin faster but need more hp to turn it but a larger pulley would turn it slower but be easier for the engine to turn. Could this work or is this a hopeless theory?

[Xylaquin]

No luck with that link I posted? I'm determined to find these parts!