Amazon: Misfiring B18

[80Sprint]

I am a first time owner of an Amazon B18 (66) but finding it frustrating as it has already developed a misfiring fault.

It can start fine and run for a short period and then, not always, misfire. It does not want to accelerate and is very hesitant and kangeroos down the road.

Plugs changed so far. Cap looks quite new and can't see any issues with it. I have also cleaned out the fuel filter.

I sense it may be electric rather than fuel. Maybe coil ? It is running the original coil. Can i test this and what is involved in upgrading to a Bosch blue coil as i plan to use this daily ?

thanks

Mike

[Burdekin]

Running lean will be one cause, how have you got the carb set up and what carb have you got? Stromberg? If so also change the diaphragm.

[80Sprint]

Running twin SU's. The plugs look a good colour.
What i don't get is why it can run fine and then suddenly start running badly, that's why i suspect an intermittent fault would be more likely to be ignition.

Also pulling the choke out makes no difference.

Mike

[Army]

My advice is to do simple things like check electrical connections and make sure that fuel lines are not resting on warm / hot places.

I once owned a Ford V6 that had a convenient multi-plug that sat near to the top of the V - the engine got warm - plug expanded - all of a sudden it was like sitting in a glider and then - BANG - backfire!

Great fun

Those were the days...

...start with the simple stuff - check connections - check fuel pipe positions - especially if you think it is happening "when things get warm"

[142 Guy]

Just to be clear, we are talking misfire and not back-fire? Then, assuming that you are correct that it is not a mixture problem, based upon your description, you might have a temperature related insulation failure leading to intermittent ignition failure. This could be the insulation in the ignition coil, the high voltage wires between the coil - distributor - sparkplugs, the distributor cap the actual spark plug caps and the perennial favorite, a failing condenser. In addition, carefully examine all the electrical connections (high and low voltage) for anything that looks dodgy. You could have a bad connection that become intermittent when temperatures cause things to expand.

Testing for insulation failure on an ignition coil is very difficult without special equipment. Its pretty much a test by replace for most people. But, start with the no cost stuff such as examination of the electrical wiring. Then move on to the lower cost items such as the condenser and the HV ignition wiring. The coil would be the last.

[arcturus]

If possible, next time it starts misfiring pull over and with the engine still running put your hand on the coil. If it's too hot to touch comfortably that may be your problem. Also lift dizy cap and check that the center contact is in good order and can push in and out smoothly .Agree imminent condenser failure also likely, hard to find good quality ones. Even the Bosch ones are made in China..

[Bob Meadows]

For quality components like condensers- rotor arms & many more try Distributor Doctor.
Link:~ http://www.distributordoctor.com/

They have developed part of their trade by solving the inferior rubbish being offered to classic car owners.
Regards Bob.

[mike gilbert]

Just to add to whats already been said. As a new owner you may not be aware that the original coil will have a built in armoured cable to the ignition switch, so you dont want to be changing that unless you have to, its a bit more involved than the average 60's car coil swap and leaves you with a hole in the bulkhead that needs filling (though you can make/buy a bracket to mount the new coil in the same place).

[arcturus]

Coil conversion.

[Ron Kwas]

Mike;

Please assure Ign Coil failure is the root cause BEFORE replacing it (as correctly notes by others, this is not a simple operation, because of the armored Ign Sys), by temporarily taking it out of the picture by wiring in another coil (troubleshooting by substitution, which depending on primary resistance of replacement coil, may require a dropping Resistor also!). See also: https://www.sw-em.com/Volvo%20Igniti...ition%20System

I agree with Bob about the horrendous quality of china**** replacement components, particularly the Ign Condensor. I have been burned by a failure of one of these components also!

Arcturus; I spy Dropping Resistors!

Cheers