Joined: Dec 2017 Posts: 1,160 Threads: 68
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Location: Nottinghamshire. Robin Hood County
Car type: Austin Ruby Mk1 1935
If the misfire only starts after a few miles it suggests it happens once the engine gets hot. By all means check the coil as these can break down when hot. Also check your tappets because these will alter when the engine is hot and if not allowed to close fully will cause misfires.
John Mason.
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.
Joined: Aug 2017 Posts: 1,042 Threads: 108
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Location: Cheshire
My Chummy used to get hot and bothered and misfire after about five miles (when I mentioned this, one of the other club members said it reminded him of his wife). Turned out to be an air leak into the manifold - so it was running lean. It proved very hard to spot.
Joined: Aug 2017 Posts: 978 Threads: 6
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Location: Scottish Borders
If it only happens with a hot engine I would suspect the tappet clearances may be too tight. as the valves heat up and expand the clearance reduces.
Jim
Joined: Dec 2017 Posts: 1,160 Threads: 68
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Location: Nottinghamshire. Robin Hood County
Car type: Austin Ruby Mk1 1935
I am with you Jim. Hence my comment to check the tappers.
John Mason.
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.
Joined: Mar 2018 Posts: 694 Threads: 33
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Location: Lot region FRANCE
And of course, the points are clean, set right and the top distributer bearing isn't worn (which could upset the points gap)
Joined: Aug 2017 Posts: 978 Threads: 6
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Location: Scottish Borders
It's worth checking the plus. If they are white it's running weak & I would suspect an air leak. If one or more are black I would suspect tappet clearance or a sticking exhaust valave,
Jim
Joined: May 2018 Posts: 2,091 Threads: 109
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Location: Llandrindod Wells
Car type: 29 Special, 30 RK, 28 C Cab
Hi
Long shot, but it has happened to me recently. Check the battery terminals and voltage at the coil. I had a very slight short on a battery lead that led to the voltage dropping to below 3 Volts. Caused a misfire after a short while of driving.
Cheers
Howard
Joined: Nov 2022 Posts: 91 Threads: 10
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Location: Norfolk
Car type: ARQ Ruby
Cheers guys, just back from a break, so will investigate all the above suggestions over the next few days, and report my findings.
Charles L, what did you mean by "fractured connection in the distributor " do you mean a crack in the Dizzy Cap ???