HELP - Spark plugs won't work
Discussion
Im in the final stage of renovating a 1937 Morris 8. But I can't get the spark plugs to spark. The whole ignition system has been renewed. Every part and some parts more than once. I have HT up to the spark plugs (tried 3 sets of plugs - new) but I cannot get them to spark when touched to earth. If I move them slightly away from earth (about 2-4mm gap) I can get them to spark from the central electrode to earth and even to the earth on the plug (so they spark normally when not touched to earth but are close to earth). Touch them to earth and they don't work.
When you hold the plug near an earth point do you get a spark from the centre electrode to the earth point, or is it going from the ground electrode to the earth point? I still think these must be shorted - since you have tried new plugs it must be the cap or lead assembly. Are the leads shielded by any chance?
I'm sure that would be positive earth. Surely there must be an owners club you can ask?
If you take all the plugs out and lay them against the block/head then spin the engine on the starter you should be able to see the plugs sparking.
As said above does the bock have a decent earth to the body?
I would earth the block to the battery earth point perhaps with a jump lead to try it.
Have you checked the plugs on something else (lawnmower?) the see that they actually spark?
Is the condenser the correct one and working?
Is there a spark at the points if you flick them with a screwdriver with the ignition on?
Sorry if this is teaching you to suck eggs but electronic computerized systems have been around for so long that it's only people of a certain age that have actually lived with a contact breaker system
My post crossed with your latest. I would be willing to bet that your modern ignition system is designed for negative earth and that the car was built with positive earth. You would surely have needed to change the starter motor and dynamo if you had changed polarity, I'd have to think about the wiper motor. Assume fuel pump is mechanical
If you take all the plugs out and lay them against the block/head then spin the engine on the starter you should be able to see the plugs sparking.
As said above does the bock have a decent earth to the body?
I would earth the block to the battery earth point perhaps with a jump lead to try it.
Have you checked the plugs on something else (lawnmower?) the see that they actually spark?
Is the condenser the correct one and working?
Is there a spark at the points if you flick them with a screwdriver with the ignition on?
Sorry if this is teaching you to suck eggs but electronic computerized systems have been around for so long that it's only people of a certain age that have actually lived with a contact breaker system
My post crossed with your latest. I would be willing to bet that your modern ignition system is designed for negative earth and that the car was built with positive earth. You would surely have needed to change the starter motor and dynamo if you had changed polarity, I'd have to think about the wiper motor. Assume fuel pump is mechanical
Edited by Etretat on Tuesday 31st October 21:55
I prefer to hold leads with either insulated pliers or plastic ones as I don't want to keep getting shocks no matter how mild they might appear to be.
Some old systems can still give quite a belt & the best one I ever had was off a BSA A10 magneto when I put a cloth wrapped finger into the opening for the lead pickup to clean the track the pickup carbon brush runs in & turned the magneto input shaft with my other hand.
Also eliminates you as the earth for the lead, although I doubt it would make a huge difference.
Could well be negative earth. This link is a pdf dealing with sluggish starting issues on Morris 8 - appreciate that's not the OP's problem.
http://www.morris8-bobbryan.co.uk/articles/M8%20Sl...
Was this a runner before the restoration began?
6 volt electrics or is it on 12v?
Frankly I doubt that 3 sets of plugs are all going to be defective & likely much the same for the rest of the stuff you've renewed.
As you've fitted a non standard ignition it's going to be difficult to diagnose & I expect many of the usual procedures that you'd follow for its conventional points & condenser system are going to be irrelevant.
Is this a complete accuspark dizzy or a conversion to the existing dizzy? Is the ignition system ballasted or not?
Link to Accuspark instructions: http://www.accuspark.co.uk/fitting_guide.html
Might want to have a chat with Accuspark.
Do you have access to a running petrol vehicle that you could borrow a plug out of just to test if you get the same result? I'd suggest if you do that that would eliminate the plugs. Same if the other vehicle has removable leads.
If you disconnect the king lead from the dizzy, attach a plug & repeat the test what happens?
Some old systems can still give quite a belt & the best one I ever had was off a BSA A10 magneto when I put a cloth wrapped finger into the opening for the lead pickup to clean the track the pickup carbon brush runs in & turned the magneto input shaft with my other hand.
Also eliminates you as the earth for the lead, although I doubt it would make a huge difference.
Could well be negative earth. This link is a pdf dealing with sluggish starting issues on Morris 8 - appreciate that's not the OP's problem.
http://www.morris8-bobbryan.co.uk/articles/M8%20Sl...
Was this a runner before the restoration began?
6 volt electrics or is it on 12v?
Frankly I doubt that 3 sets of plugs are all going to be defective & likely much the same for the rest of the stuff you've renewed.
As you've fitted a non standard ignition it's going to be difficult to diagnose & I expect many of the usual procedures that you'd follow for its conventional points & condenser system are going to be irrelevant.
Is this a complete accuspark dizzy or a conversion to the existing dizzy? Is the ignition system ballasted or not?
Link to Accuspark instructions: http://www.accuspark.co.uk/fitting_guide.html
Might want to have a chat with Accuspark.
Do you have access to a running petrol vehicle that you could borrow a plug out of just to test if you get the same result? I'd suggest if you do that that would eliminate the plugs. Same if the other vehicle has removable leads.
If you disconnect the king lead from the dizzy, attach a plug & repeat the test what happens?
Edited by paintman on Tuesday 31st October 22:59
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