1968 Austin 1100 Mk1 (Take 2)

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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by Hooli »

I've found loads of that 'odd looking first fuse' in old Brit cars & bikes, must have been a common make at one point.
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by SiC »

As far as I'm aware they are just high current fuses. You also get fast acting fuses with a spring in. So as the wire heats up, the tension on the fuse wire causes it to blow quicker. Likewise slow blow fuses that can take fast acting surges without blowing. Such as large motors switching on and other similar heavy inductive loads.

As a kid my dad had a whole box of glass fuses. Much fun had by myself with them and a 20A variable power supply. Trying to get them to draw enough current to glow but no blow. Or the trigger the quick acting ones to see the rather dramatic action of the spring pulling the fuse wire apart.
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by DodgeRover »

How difficult would it be (for you) to make something with a chip on it do to the same as the regulator box. New ones regularly give grief as obviously they are made by the lowest bidder rather than the one who will give a warranty..
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by SiC »

Part of the reason why I am persevering with this to learn how they work. However there already exists products that replace this in different forms.

One way is to replace the dynamo with a Dynamator if you want the high current capability of a alternator in something that looks like a Dynamo. Pricey though.

Secondly there are several solid state regulators already on the market. E.g. http://www.classicregulator.com/ and others. However you're still limited by the max current of the fitted dynamo which is quite poor.

The 1100 has a 22A dynamo. Two 55w headlight bulb, two 5w side light bulbs and two 5w rear bulbs is drawing 10A at 13v and the coil is around 3.5A when running. Then a Lucas wiper motor iirc is around 3A. So you're already at 16.5A. Turn the heater fan on can be another 3A or more. You're now at the rated capacity of the dynamo! Also it won't have anywhere near the capability to provide that unless running at like 3k rpm. So you end up discharging when sat at lights and barely replenishing that energy when on the move.

Alternatively the other solution is you can lob a generic 17ACR style alternator at it and have twice the current capability (40A) for £50 off eBay. This will provide far more enough power to run a car even at low revs and still charge the system. Won't go out of adjustment and provide that power without derogation. If it does break, you lob another £50 one at it and no fiddling around needed to set it back up. No wonder most would choose this option!

Thus limiting the market for a solid state regulators. If you're perverse enough to be running a dynamo, you probably also wanting the original electromechanical control system attached to it. Likewise there is little market for converting classic cars with carbs to Fuel Injection.

But that's not as interesting to own of course! (I'll probably change that view when I run out of electricity one evening)
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by Hooli »

I'd never thought about the ampage of a coil before, that's higher than I'd have guessed but I'm sure you're right.
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by DodgeRover »

SiC wrote: Sat Aug 08, 2020 4:23 pm Part of the reason why I am persevering with this to learn how they work. However there already exists products that replace this in different forms.

Thus limiting the market for a solid state regulators. If you're perverse enough to be running a dynamo, you probably also wanting the original electromechanical control system attached to it. Likewise there is little market for converting classic cars with carbs to Fuel Injection.

But that's not as interesting to own of course! (I'll probably change that view when I run out of electricity one evening)
I knew the charge rate was low, but can you not alter the pulley size to give the max charge rate at a lower rpm? I'm assuming you aren't planning on long motorway stints in it so over revving the dynamo probably wouldn't be an issue.

Now the perverse side of me would actually like to fit a home brew fuel injection set up with the caveat that I knew how it functioned and how to repair it to. A certain furry person from the beige mentioned on RR he was planning to fit fuel injection to one of those infidel cars using over the counter parts designed for converting motorcycles
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by SiC »

Hooli wrote: Sat Aug 08, 2020 8:18 pm I'd never thought about the ampage of a coil before, that's higher than I'd have guessed but I'm sure you're right.
V=IR
(Volts = Current / Resistance)

R = V/I

12v / 3 Ohm coil = 4 Amps
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by fried onions »

If your ignition coil is drawing 4 amps it'd burn out in no time. A perfect example of the theory not matching what happens in practice. The real figure is measured in mA.
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by fried onions »

This CVC of yours will be a development of the RB. 310 '3 bob job' used on my Humber. I have just about finished setting it up as best I can. As long as you bear in mind all the functions are separate but work together you will understand it; patience is key. There's nothing to be gained by geeking over it with the lab crap. The only way to set it up satisfactorily is on the car through trial and error. With everything functioning correctly, a fitted ammeter would show a high charge rate of up to 30 amps upon starting the engine, which rapidly falls off as the car is driven away to a trickle charge of a few amps, or even just above zero. The initial high charge is to replenish the battery after using the starter motor. Any further load such as headlamps should be balanced as shown by the ammeter putting back into the battery the same as before the load was switched on, i.e. a trickle charge.

Now for voltage. On these 3 bobbin types the voltage control affects the cut-out as you have found. Temperature plays its part so be mindful when making adjustments; when starting up from cold the cut-out may not close if you had made the previous adjustments during or after a run. The cut-out closing voltage is not so critical - what you want is a system voltage within acceptable parameters with the cut-out working reliably, in other words with the engine sped up and the cut-out contacts closed, the battery voltage should be between 13.5-15 volts. You could measure this whilst driving from the cigar lighter socket or any convenient point, ask a passenger to hold the meter leads.

There must ALWAYS be an adequate gap between the cut-out contacts, and they must always open smartly below cutting-in voltage. If they remain closed below the cut-out threshold the full battery current is fed to the dynamo which will try to motor up, the ammeter will be off the scale discharging and if not caught quickly you can guess the rest. This is why the ignition light glows at engine idling speeds.

As always, the old signs are the best. Check if the headlights increase in brilliance and by how much, check for blackened bulbs, and keep an eye on battery electrolyte level. Frequent topping-up is a sure sign of over charging.
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Re: 1968 Austin 1100 Mk1 (Take 2)

Post by SiC »

fried onions wrote: Sat Aug 08, 2020 10:00 pm If your ignition coil is drawing 4 amps it'd burn out in no time. A perfect example of the theory not matching what happens in practice. The real figure is measured in mA.
4000mA? :lol:

Ok ok I wasn't taking into account dwell time.

1100 is 60 degrees, so let's use that.

60/90 gives us a duty period of around 66%.

4*.66 = 2.64A

Ok ok yes it's not a step response from power applied to fully saturated as a coil of course is an inductive device. That also changes with revs. But I can't be fucked to calculate that while on my phone.

I'd be very surprised if it was tens or hundreds of milliamps in practice though as the ramp up is pretty quick when looking at traces floating around the net.

I'll lob the current clamp over the negative lead of the coil tomorrow and measure it. If I really even can be bothered I'll dig out the scope and current clamp to plot it.

However even in that video I made of the clamp earlier in this thread was showing a draw around the 2 amps mark. No other drain apart from the fuel pump, but you'd see that draw blipping the measurement when it was drawing fuel.
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