Misfiring solved ! (I hope)

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Mike Stevens
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Re: Misfiring solved ! (I hope)

#11 Post by Mike Stevens » Mon Mar 30, 2015 11:54 am

I think that another advantage of a modern points-less system is that you can get a 'black box' that controls the advance rather than using springs and weights, leaving the vacuum advance (retard?) as-is. The advance can then be set up by connecting a laptop, giving the possibility that the advance Vs RPM curve could easily be 'trimmed' to suit the car with modern fuels - starting with the 'standard' curve of course!

All this for <£100 and something I am sorely tempted to try. However, I still have the old points system at present so will need to change that first!

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Mike.
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Re: Misfiring solved ! (I hope)

#12 Post by Alec » Mon Mar 30, 2015 2:36 pm

Hello Mike,

I don't think the fuel has much to do with it, the curve is more due to the internal characteristics of the engine and burn rate in the combustion chamber. Certainly the base timing may be different than fuel when the car was new but the overall curve itself will be much the same.

An interesting book, although not an easy read, is Roger Bywater's (AJ6 Engineering) 'Engine Technology for the Modern World, Bridging the gap between the Enthusiastic Layman and the Expert. (ISBN 978-0-9567763-1-0). For instance it describes the three phases of a plug sparking, would you believe 200 amp for the first few billionth of a second?
He also explains why it is not a good idea to open the standard spark plug gap.

Alec
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Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.

Clifford Pope
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Re: Misfiring solved ! (I hope)

#13 Post by Clifford Pope » Mon Mar 30, 2015 4:54 pm

Mike Stevens wrote:I think that another advantage of a modern points-less system is that you can get a 'black box' that controls the advance rather than using springs and weights,

But the Aldon Ignitor does retain the weights and springs, doesn't it?
Or are they meant to be disabled in some way?

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Re: Misfiring solved ! (I hope)

#14 Post by Alec » Mon Mar 30, 2015 6:27 pm

Hello Cliff,

that is just electronic switching but no advance capabilities, so uses the mechanical/vacuum advance system.
The 123 distributors have solid state advance system that has some limited programming capability by dip switches and with another version that you can use a computer to programme but I would imagine that is a bit more than about £100.00?

Not my cup of tea personally.

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.

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Re: Misfiring solved ! (I hope)

#15 Post by Mike Stevens » Tue Mar 31, 2015 11:55 am

The one I was looking at works with an Aldon ignitor (or other similar products). It connects between the 'ignitor' and the coil and controls the advance (and dwell) depending on engine speed and non-volatile settings within itself.

They show how to disable the mechanical advance and various PC screen shots of advance curves etc.

Far be it for me to disagree with you Alec, but I'd have thought that the optimal advance characteristics would depend on fuel. We know that the octane rating defines the SIT of the fuel and hence the advance that can be tolerated at any given engine load. Modern fuels are vastly different to those in use when these engines were designed, so I'd have thought the advance curve set then would not be optimal now.

Just my thoughts, not really based on any real facts!

Cheers,
Mike.
(South Oxfordshire)
Register Member No 0355
1971 2.5PI Saloon Sapphire blue
1973 2.5PI Saloon rust some Honeysuckle
1973 Stag French blue
(1949 LandRover was blue should be light green!)

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Re: Misfiring solved ! (I hope)

#16 Post by Clifford Pope » Fri Apr 03, 2015 8:42 am

I've bought an Ignitor kit, and on reading the instructions it says I need to set up the basic static timing approximately first.
It suggests making paint marks on the magnetic collar corresponding with the position of the magnets, and then turn the distributor until the magnet corresponding to firing plug No.1 points at the centre point of the module.
That makes sense, but there are no markings on the collar to indicate the position of the magnets - it is an entirely featureless piece of plastic apart from the reference number and four casting marks on the top.
I would guess that the magnets are somewhere in the thicker section of plastic in between the lobes, but not halfway because the ignition needs to trigger on the upward slope of an approaching lobe, as with the old contacts?

So how have others identified the magnets - compass, iron filings ?

It stresses the importance of a good earth to the new plate, saying use the new securing screw (=old points locking screw) to fix the earth wire that used to be held by the capacitor screw. But a) that is a small screw with a small lug on the end, too small for the larger securing screw, and b) the braided cable is very thin and not really long enough to stretch across to the new screw.

Would it be a good idea to run a new earth wire instead out through the side and bolt securely to the engine block?

Can the device be set up to static timing like the old one (and Lumenition I remember) by connecting up bulb or a meter to the coil and turning the distributor until it registers? I've always previously set timing to 8 degrees or whatever just by setting the crank pulley and then listening for the spark or click while turning the distributor back against the heel until the contacts open.

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Re: Misfiring solved ! (I hope)

#17 Post by tony » Fri Apr 03, 2015 8:56 pm

I've got a pertronix which I believe is similar to yours. I set it up with a lamp as you've described initially then check it with a strobe light.
Tony.
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Re: Misfiring solved ! (I hope)

#18 Post by Clifford Pope » Sat Apr 04, 2015 10:25 am

Thanks Tony, that seems the best thing to do. I don't like the idea of starting it with a random timing setting, and the advised method of aligning the magnets just doesn't seem possible.

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Re: Misfiring solved ! (I hope)

#19 Post by Clifford Pope » Sun Apr 05, 2015 8:37 am

This isn't going well. I've got it nearly fitted but now I can't get the collar on. Looking at the scuff marks in the plastic the moulded profile does not quite match that of the cam lobes - the lobes seem to come to a more acute point, and the cut away sections are a fraction thicker. So I am very fearful that if I press harder the collar will split.
The kit says it is for the Lucas 45D distributor - Aldon LU 163.

Should I risk forcing it on, or is it the wrong collar? (I do remember when fitting a Luminition in the past that the kit came with a selection of very slightly different plastic blades, and you selected the one that best matched the individual machining of the cam lobes.)

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Re: Misfiring solved ! (I hope)

#20 Post by Alec » Sun Apr 05, 2015 9:18 am

Hello Cliff,

I'm sure that it is not meant to be forced on.
I note from the Aldon website that they have two versions to suit the 45D distributor, yours and an LU164, depending on the type of points.
Personally I would contact Aldon and explain your problem rather than risk damaging what you have?

Alec
0465

MK1.5 2.5 P.I.
Jaguar MK 2 (Long term restoration.)
Hymer 564 Motorhome.

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