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MG MGB Technical - Smoke and burning electrics

Hi guys,

74 Chrome BGT

Quick one here, a couple of days ago I rigged up a coil cut off switch on the feed side of the coil, I chose to put it there after reading numerous archives and because it was simple (I am a mechanical engineer afterall and just don't do electrics). The switch ran on 10A+ wires to a 10A rated swith under the dash.

Whilst pulling onto the drive yesterday I saw smoke pouring out of the bonnet and quickly turned her off. The original coil feed to fuse box cable had burnt out, but I just don't understand why?. I've done nothing complex here just installed a switch to break the circuit, so any suggegions as to why this would have happened or would it have been down to a short somwhere in my work??

I'm thinking or trying this again as I still se no reason why it wouldn't work, although I'll install a in-line fuse this time. But should I put this switch somewhere else? I've read in the archives about a switch in the coil to points line, so am considering that. Additionally I inted to pursue the battery and fuel cut off switch options, although I'll probably just go with the battery cut off as I'm less likely to screw it up.

Thanks

Craig
c smith

Craig,

I am just curious. Why would you want a cut off switch to the coil anyway. I have had a MG for 28 years and never once had a problem with the coil wire.

If the feed goes to the fuse box there is already a fuse so I am not sure I understand. This one is new to me and maybe others as why you are doing it.

Please explain.

Ray
http://www.treasure-island-jewelers.com/1977mgbSupercharged.htm
Ray 1977 MGB

Hi all.

Ray, I think Craig was fitting an immobiliser switch, for security purposes.

Craig, it sound very much as if you have a short to chassis somewhere in your new wiring, or you have left the end of an original wire 'floating' and it is shorting.

Don
Don

Earth on faulty switch ? - the fuel pump option has saved two cars for me.

Roger
RMW

This thread was discussed on 09/09/2005

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