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MG Midget and Sprite Technical - AccuSpark Electronic Ignition

I have been struggling fitting an AccuSpark Electronic Ignition to a 75 1500 midget, initially I wired the positive wire to the coil not realising the 1500 has a ballast resistor (please correct me if I am wrong).

I have the negative wire going to the coil via the connection through the loom as per the old standard distributor.

The car failed to start and after many hours adjusting found the live should have been wired via the fuse box

I know this is probably obvious to most but could someone please confirm which is the live side of the fuse box, as the instructions say not to go through a fuse.

The fuse box is the original fuse box.

Thanks Tim

Tim Lynam

IIRC the live side is nearest the battery tray & heater.
David Smith

Easy to check with a cheap voltmeter. Remove a fuse at random. Check for voltage between the fuse holder ends (red probe) and any earth point or battery negative pole (black probe). The side of the fuse holder that shows a voltage is the "live".
I know this is super-simplistic but it's always possible on an old car that something has been changed from standard original, so a positive test is useful.
You don't even need a meter. A 12v light-up type checker can be found on market stalls for a quid or so, but test it across the battery first to verify it works.
Cheers.
Greybeard

If you still have standard wiring, connect it where the white wires are.
Dave O'Neill 2

Tim,
it's as David, Greybeard and Dave have put but I'd also add that making up a simple test wire kit with a 12v bulb is often better than using a cheap modern digital multi-meter.

When I first got my Midget I needed to test that the reversing light units worked so I made up a twin wire that was long enough to go from the battery to the reversing lights with plenty of slack so that I could test the units in situ using either live or earth or both directly to the battery. I had (crimp) connectors on the ends so that I could make up and attach any type of connector required for what was to be tested, one was a bulb.

Whereas when I bought a cheap digital multi-meter possibly because it was rarely used it only lasted about 18 months. As a present a friend bought me a replacement a bit later, turned out to be same digital multi-meter but with a different makers label, this only lasted about 13 months (Sod's Law it lasts just more than 12 months) before it gave unreliable readings so worse than no readings.

I see analogue meters are freely available again but I'm not sure I'd trust them to be any better manufactured unless you pay for proper pro units.

Lastly my previous fusebox was wired correctly but was other way round to original which confirms the need to check, even when everything works fine.
Nigel Atkins

Thanks for all the comments, it sounds quite obvious how to check when explained as well as above.

The live side was found easily with a multi meter and hopefully the electronic ignition is now wired in correctly, the car spluttered into life, ran like a bag of nails for a couple of minutes, slightly adjusted the dizzy and wont start again.

Have others struggled getting the car restarted after swapping from standard to electronic ignition?

Hopefully got the timing at TDC and rotor arm pointing to No 1 lead, I read somewehere that the timing could be a long way out for electronic ignition to run, but mines not straight forward.
Tim Lynam

Have you checked that you've got the plug wires going to the correct cylinder? They'll sometimes run if you've got two wires crossed. Don't ask how I know.
Martin

It sounded as though the leads may have been wrong when it did run, but I believe them to be correct, hope I'm wrong!

Firing order 1 - 2 - 4 - 3 going clockwise on distributor as photo.

Tim Lynam

1-3-4-2
GuyW

Thanks Guy, thought you had spotted the problem, but I had written it clockwise (incorrectly) but anti clockwise as per pic is set up 1-3-4-2 which is correct?
Tim Lynam

Off hand l cannot remember if the 1500 is anticlockwise or not. I just take the cap of to check which way it goes.
GuyW

1-3-4-2 counter clockwise rotation. Firing timing I think is 10 degrees BTDC.

#1 is at the lower left of the cap.

My '76 Midget turns 41 this month!!!!

Cheers,
Clare
C Ravenwood

At what I believe is TDC No 1 is at bottom right hand of the cap, about 5'O Clock (looking from front of car) but could this be different on all cars depending how the dizzy is set up?
Tim Lynam

Photo of what Clare and Guy have put.

I put a thread for the Archives detailing firing order to dissy cap.

ETA: I typed as you posted, the answers are yes and yes.

Nigel Atkins

Tim,
it won't be the cause of not starting (unless it's the coil lead) but the Accuspark kit is very keenly priced and you get a lot for the money so something has to give and from what I've previously seen the Accuspark HT leads can be not so well put together.

IF you are concerned about this it is easily checked by replacing the Accuspark HT lead set with the previous set - provided of course the previous set worked.

For future reference a very well made HT set, made in the UK too, is from 'performanceleads' they make set for others to put their name on - http://www.fla-manufacturing.com/products/index
Nigel Atkins

The engine will be at TDC on number one cylinder two times for each revolution of the distributor.

You need to make sure that the plug leads are not only in the right order, but also the correct lead is opposite the rotor arm on the firing stroke and not on the exhaust stroke.

Have you checked that you are getting a good strong spark at the plugs?

Do you have a good quality rotor arm? If your electronic ignition is boosting the coil voltage, it might be enough for your rotor arm to start misbehaving.

Check sparks first.
Dave O'Neill 2

I had a good spark at the Coil and at No 1 plug a few days ago, but after changing wiring decided to recheck No 1 plug for a spark, as soon as engine turned and No 1 plug close to engine block had a massive backfire bringing the neighbours out! so looks like the timing may be massively out?

Is there a straight forward way to check at TDC on No 1 lead on the firing stroke and not on the exhaust?

The old leads and plugs had previously been put back just to check they are not at fault but still no joy starting, only thing not replaced is rotor arm but after waking the neighbours with the misfire will try another day!
Tim Lynam

1. Remove rocker cover
2. Remove all spark plugs
3. Slowly rotate engine & watch for both #1 rocker arms to close (valves in the up position).
4. Watch in #1 spark plug hole for piston to get to the top (you'll probably need a flashlight to see in there)

It won't be the precise zero top dead center but it should get you close enough to know where the rotor is pointing & which wire is #1. The car should start from there and allow for you to tune.

Forgive what may be a stupid question: There are 2 AccuSpark systems one for vehicles with ballast resistor, the other without - do you have the correct system.

Is it possible the ballast resistor is defective?

Just some thoughts, good luck!
s1

Thanks for the explanation, pretty much what I had done but not with both valves in up position so may be out a little.

I have the AccuSpark system for the ballast resistor (blue coil) but not checked if ballast resistor working, is there a test?

Car ran well before changing to new distributor.
Tim Lynam

The simple way is to remove the #1 plug. Turn the engine over by hand (i.e put it in gear and rock the car forward) whilst covering the plug hole with your thumb. This way you will feel the compression stroke.

When at the top of that stroke, remove the dizzy cap and check which dizzy post the rotor arm is pointing at. This is the #1 plug lead. Connect this lead and the others in the right sequence 1-3-4-2, going anticlockwise.

This should be close enough for the car to start and run. You can then fine-tune the timing by slackening the dizzy clamp slightly and moving the dizzy as the car is running. Or by using a strobe if you have one. basic ones are pretty cheap these days.
GuyW

My experience of Accuspark is not good. I was asked to fit an Accuspark dizzy to a Friend's IOW Frogeye.

First the carbon brush fell out of the cap. Then a lead was found to have not been connected. Then the module was found to be defective. After a couple of hours I gave up and the Dizzy was returned for a refund.

Alan
Alan Anstead

My 76 was converted back to points. Easy to install, change and adjust and best of all, no electronic bits and pieces to suddenly fry and leave you stranded in the middle of nowhere.

Cheers,
Clare
C Ravenwood

Just caught up.

Sorted now Tim?
Dave Squire

OK another goof proof way to check.Thumb over No 1 plug hole with plug resting on block. Ignition on and crank one or two revolutions. Pop under thumb and spark should coincide - basic but fool proof.
Fergus

Thanks for the tips, no not sorted yet, my GLW helped for the first time turning ignition but after having the first ever back fire and frightening living daylights out of her don't think she will be helping to check for spark at plug again!

Will have another go at weekend but wondering if another dodgy dizzy like Alans's or is it just me getting it wrong.
Tim Lynam

Surprised someone I know has not joined in on the quality of their timing lights.
Alan
Alan Anstead

Problem now sorted, all AccuSpark parts working ok, problem was found to be with the dizzy clamp not securing dizzy and lifting when car attempted to start so rotor arm spindle jumps out so not engaging, just need to sort the clamp out, but car now runs, what a relief!
Tim Lynam

Good news. Isn't it frustrating when it's something so simple and easily overlooked?
Martin

Good catch Tim
Greybeard

Very Frustrating! I have been struggling for 3 weeks for something so simple, but easy to miss the obvious.
Tim Lynam

I like a happy ending.

Clare
C Ravenwood

Tim,
I know (only too well) what you mean about this being a bitter/sweet episode but I think overall you can be pleased as I don't think it was something that was obvious. It may have been thought of in perhaps a previous thread but it wasn't mentioned in this one, so obviously, not that obvious.

I'd suggest you now go through the whole set up so that once its done you can enjoy the improvements it brings (and unlike points have to fart about resetting after a few hundred miles of bedding in resetting every x number of miles).

check in this order and adjust as required -
valve clearances, plugs, timing, carbs mixture

Then drive the car to enjoy it.
Nigel Atkins

Car now running nicely, but all the trouble was caused due to the dizzy clamp either not being tall enough as it is at a slight angle and does not grip the whole of the distributor, or the distributor is a bit taller than previous one or not seating correctly, anyone had issues with the dizzy clamp not gripping correctly on a 1500?
Tim Lynam

Tim, I call it the 10/10 repair. 10 hours of diagnostics and 10 minutes to fix it. Hey, crack open a cold Stella Artois and have a laugh. I do ALL the time.

Cheers

Gary
79 MGB
gary hansen

Tim, is it an original distributor or an aftermarket one? I found with my spare aftermarket one, the fit of the clamp wasn't as good as the factory one. I don't think the aftermarket one fitted an original one or something like that. It was quite a while ago but that could be your situation.

Clare
C Ravenwood

Clare, its an AccuSpark Electronic distributor, the clamp supplied was totally different so used the original clamp, but the clamp in its original position sits too low to clamp well onto the new dizzy, it just seems strange and wondered if others had a similar issue as many have swapped over to electronic ignitions and fitted new dizzys's.

Gary, the Stella is on ice until the dizzy is nice and securely clamped, nearly there just cant risk the chance of it becoming loose on the cars first trip to foreign soil in a few months.
Tim Lynam

Tim,
a few quick thoughts -
. could the clamp on the car be a non-original type
. rough up surfaces of dissy and clamp (and perhaps add something like thread lock, adhesive or seal)
. as well as roughing up dissy and clamp or instead of, add a thin bit of textured material between dissy and clamp to add grip and bulk
Nigel Atkins

Nigel, thanks for the ideas, I am 99% certain its the original clamp, so looking at making a thicker gasket to fit in between dizzy and engine to raise it a mm or two which should be enough to raise clamp to fit nice and straight round distributor, just surprised no ones had similar issue, but always good to receive ideas.
Tim Lynam

This thread was discussed between 14/01/2017 and 31/01/2017

MG Midget and Sprite Technical index

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