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Re: Mgb misfiring and spitting fire!!!

Posted: Fri Aug 21, 2015 7:36 am
by Fatbloke
Thanks History.

However as readers of my trials and tribulations will know, I completely replaced everything on my HT and LT systems last year before discovering that my timing was inexplicably 90 deg out :oops: so That is why I was was thinking Carb especially as I have done nothing to it other than occasionally twisting the adjuster knob on the bottom, since I bought the car 14 years ago!. (If it aint broke...)

But as you say, It looks like the black rotor may be the problem.

I've sourced a red one on James Paddocks for 2.95 + VAT. is this the ones you're all talking about?

Sorry Gt67. I didn't mean to hijack your thread, especially with a Triumph. But our problems seemed similar... hope you don't mind too much.

Re: Mgb misfiring and spitting fire!!!

Posted: Mon Sep 14, 2015 10:52 pm
by Cambronne
This little tale may be relevant.

I took a trip with the owner of a Dax Cobra replica, fitted with the 5.3 litre V12 from an E-type. Driving through Thorne, near Doncaster, the car developed a spectacular misfire. This involved not just spitting back through the inlet trumpets but actually firing through them. It even blew the forward end of the left sidepipe out of its socket.

We stopped, and as the good folk of Thorne were doffing their tin hats and taking down sandbags, the AA man was called. He quickly diagnosed tracking across the big, circular 'rotor arm' - you could see paths burnt across its upper face.

Of course, the man who can didn't carry a spare Jag V12 rotor arm. He painted the existing one with AA van yellow. This filled cracks in the rotor arm and after its makeover, the original item took us all the way to Harlow. Top marks!

So, eight fewer cylinders but the principle is the same.

Re: Mgb misfiring and spitting fire!!!

Posted: Mon Sep 21, 2015 9:28 pm
by Toledo Man
Always check the ignition before moving on to the fuel system. There are some poor quality ignition parts (not just rotor arms) so make sure you get decent quality parts. Yes, electronic ignition can fail so it is a good idea to have a set of points and condenser to hand to get going again.

Re: Mgb misfiring and spitting fire!!!

Posted: Fri Sep 25, 2015 4:41 pm
by gt67
its all sorted now. Thanks for everyone advice. After doing everything you would normally do with a misfire with no luck, I had a friend look with me. Somehow there was a short-circuit affecting the points which prevented them sparking. Took them off, put them back on checking nothing metal was touching in the wrong places, and off we go!!!!