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alastairq
Joined: 14 Oct 2016 Posts: 1953 Location: East Yorkshire
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Posted: Sun Nov 01, 2020 8:18 pm Post subject: |
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Daft I know..but is the coil wired up the right way for the earth polarity? _________________ Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces. |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Sun Nov 01, 2020 10:33 pm Post subject: |
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alastairq wrote: | Daft I know..but is the coil wired up the right way for the earth polarity? |
I know it affects how the plug electrodes erode but I'm not aware of it being critical to engine starting.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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alastairq
Joined: 14 Oct 2016 Posts: 1953 Location: East Yorkshire
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Posted: Mon Nov 02, 2020 12:27 am Post subject: |
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peter scott wrote: | alastairq wrote: | Daft I know..but is the coil wired up the right way for the earth polarity? |
I know it affects how the plug electrodes erode but I'm not aware of it being critical to engine starting.
Peter |
It can result in a reduced spark. _________________ Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces. |
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Rootes75
Joined: 30 Apr 2013 Posts: 3814 Location: The Somerset Levels
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Posted: Mon Nov 02, 2020 8:04 am Post subject: |
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Yes, connected either way the coil will still produce a spark. The difference being that the incorrect way will produce a much weaker spark.
We were wondering if the starter would be sapping all the battery power and that may be the issue? _________________ Various Rootes Vehicles. |
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alastairq
Joined: 14 Oct 2016 Posts: 1953 Location: East Yorkshire
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Posted: Mon Nov 02, 2020 11:03 am Post subject: |
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Quote: | We were wondering if the starter would be sapping all the battery power and that may be the issue? |
You could try disconnecting the starter from the vehicle supply, and operating it from an independant battery? _________________ Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
----------------------------------------------
Ford Pop chassis, Ashley 1172 bodyshell, in pieces. |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Mon Nov 02, 2020 1:26 pm Post subject: |
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alastairq wrote: | peter scott wrote: | alastairq wrote: | Daft I know..but is the coil wired up the right way for the earth polarity? |
I know it affects how the plug electrodes erode but I'm not aware of it being critical to engine starting.
Peter |
It can result in a reduced spark. |
Full Link to subject: https://mgaguru.com/mgtech/ignition/ig104.htm
Quote from above article..."Why then do we worry about coil polarity? Because the spark plugs do care which way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going. So the spark plug prefers to see a voltage potential that is negative on the center electrode and positive on the end electrode for the very first hop of the spark. Oddly enough, this has nothing to do with polarity of the vehicle electrical system, but it is influenced by the common connection inside the ignition coil. End Quote. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire
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Posted: Mon Nov 02, 2020 4:00 pm Post subject: |
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If everything else was ok , the coil being fitted the wrong way round won't prevent an engine from starting, unless the spark is so marginal (for other reasons) that its the straw to break the camels back.
Dave |
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Rootes75
Joined: 30 Apr 2013 Posts: 3814 Location: The Somerset Levels
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Posted: Sun Nov 08, 2020 6:18 pm Post subject: |
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Well, finally we have the Commer engine running!
We have literally tried everything so thanks for all sugestions. In the end we removed the starter motor as we thought it may be taking too much power resulting in a poor feed to the coil.
But, when we bench tested it we found that although she spins up the engaging dog didnt travel far enough, so cleaned and oiled etc and we got the right amount of travel. We refitted it but firstly checked the ring gear for tooth wear, it was fine.
Next we connected everything back up and now she was turning over at a really good speed but still not even firing. So we checked the spark at the plugs and it was very weak, then at the contacts and this was good. So, we took a look at the sprung graphite in the cap and we found its movement very small. So, I had a dizzy from one of Hillmans on the bench and we changed the graphite over. This time with everything reconnected she fired straight away on full choke, not only fired but stayed running. Lots of relief and plenty of smiles!
We have to now fit a new downpipe gasket and replace the brass nuts and then hopefully she will run with no choke, at present you can hear her sucking air in so obviously messing up the mixture. _________________ Various Rootes Vehicles. |
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alastairq
Joined: 14 Oct 2016 Posts: 1953 Location: East Yorkshire
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Posted: Sun Nov 08, 2020 7:08 pm Post subject: |
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Splendid. Onwards and upwards?? _________________ Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
----------------------------------------------
Ford Pop chassis, Ashley 1172 bodyshell, in pieces. |
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kevin2306
Joined: 01 Jul 2013 Posts: 1359 Location: nr Llangollen, north wales
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Posted: Sun Nov 08, 2020 7:51 pm Post subject: |
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That’s great news indeed.
Kev |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Sun Nov 08, 2020 10:30 pm Post subject: |
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kevin2306 wrote: | That’s great news indeed.
Kev |
+1
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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old iron
Joined: 22 Mar 2016 Posts: 185
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Posted: Sun Nov 08, 2020 11:21 pm Post subject: |
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Pleased to hear that you have now resolved the mystery |
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Rootes75
Joined: 30 Apr 2013 Posts: 3814 Location: The Somerset Levels
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Posted: Sun Nov 08, 2020 11:25 pm Post subject: |
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Its funny but we've all been at this restoring/tinkering business for a long time but there is always something new with each vehicle that can stump you or have you running round in circles! _________________ Various Rootes Vehicles. |
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badhuis
Joined: 20 Aug 2008 Posts: 1390 Location: Netherlands
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Posted: Mon Nov 09, 2020 10:01 am Post subject: |
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Excellent news! _________________ a car stops being fun when it becomes an investment |
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Rootes75
Joined: 30 Apr 2013 Posts: 3814 Location: The Somerset Levels
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Posted: Sun Nov 15, 2020 1:49 pm Post subject: |
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Another morning tinkering, she was still only running on full choke so we have stripped and cleaned the jets etc and not she starts and ticks over without any choke!!
She is still sucking in plenty of air as I am waiting for a downpipe gasket. Again, as so many times before Speedy Spares have found one for me. Can't recommend them highly enough. _________________ Various Rootes Vehicles. |
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