So I changed the plugs and capacitor and hey presto! No difference whatsoever...

I checked the points as best I can; with 3 thicknesses of coke can, supposedly 1 thickness of coke can is 4thou... It seems ok, but I realise this isn't a very scientific measurement. Maybe I need to buy/borrow feeler guages and try again...

However, it starts and runs perfectly even from cold, the problem is just that it starts missfiring badly when it revs - that doesn't seem like points, but I could be wrong. I'm at a bit of a loss as the cause, maybe the coil?

Assuming it's a coil engine - try a new coil? I have always understood that condensors just pack up - as can coils - but coils can also break down over time. Maybe yours is getting weary and can't cope with higher revs?

Nick

Hello Tom,

What sort of Distributor do you have?

Regards

Barry R

Tom,

Be careful you dont fall foul of replacing one duff component with another duffard!! The old condensers break down, i went through testing loads with a mega ages ago and most of the old ones were rubbish. Of the original condensers there were two types amongst my dads stuff in the garage, long ones that filled the complete slot in the distributor and shorter ones that stopped at the bracket where they screw on. The short ones all out performed the longer ones. If you get one out of a mini they can be made to fit and are orders of magnitude better.

Also the coils on minis and metros all work at six volts (this is a very cheap way to pick up good spare oil filled coils as the old ones go duff as the pitch drys out and cracks) Any coil with a ballast resistor is actually a 6 volt coil.

The other thing to try is to make sure the earth connection on the distributor is good. On the cars with manual advance / retard the earth connection is through the spigot which is a sliding oil and grease filled fit. Connect a wire from the clamp screw that holds the lever arm on the side of the distributor for the ADV/RTD mechanism to one of the long screws that holds the dynamo together. This definitely makes a big difference to top end speed, i have seen an austin seven van go from a max speed of just over 40 to doing 60 just for the sake of 4 inches of wire.

Apart from that make sure the top of the coil, HT leads and distributor cap are all clean.

Good luck!

Regards

Rob

Something else you might look into are the valve springs. Is it misfiring on all cylinders or just one. If all it is not valve springs.

Another possibility is the HT wires to the plugs. Are they in good shape.

Good luck
Pat

I finally found the problem, by accident. The small bolt that limits the advance and retard travel where the distributer body fits into the casting on the end of the dynamo had come undone. It seems that this is a vital part of the earth circuit for the ignition, and it was causing the spark to fail. I've tightened it up, and its back to normal...

Tom - I may have missed this in an earlier post, in which apologies. Is it a manual or auto advance distributor? Nick

its a standard manual distributer, 1928 i guess; automatic advance is cheeting a bit!!!

.

Tom,

I take it that the distributor is still free to move. There is usually a small coil spring and a washer between the bolt head and the distributor plate to allow advance/retard to take place when required, but to hold it still the rest of the time - as well as assisting the electrical circuit no doubt.

I am surprised that the retaining bolt makes that much difference to your problem since there is about five square inches of metal to metal contact along the distributor body into the dynamo end casting.

Perchance you did not knock or disturb the condenser whilst tightening the bolt?????

Mike