Ignition Fault, mystery
- by Eddie Loader
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Twice in the last 20 years I have encountered an unusual and hard to diagnose complete ignition failure on DK distributors (these have a Bakelite base plate as per the photographs). After the usual initial steps (i.e. changing the condenser and checking that there is output from the coil) met with no success, there is still no spark reaching the plugs, even flicking the points open fails to generate a spark.
The problem was cured by changing the Bakelite base plate, so what causes it to fail, on closely examining the base plate, I noticed the left hand position for one of the securing setscrews had a brass washer cast into the Bakelite (see photograph) the securing setscrew tightens down onto this brass washer.
On investigating further I found that the brass washer is part of the earthing system that is laminated into the baseplate. This system supplies the earth return for the condenser and C/B points (see photograph). If there is a break in this system it is impossible for the distributor to function normally.
So what can be done if this happens on the road miles from anywhere and you don't carry a spare baseplate? The temporary get you home answer is rig an emergency earth by using a very thin section of insulated wire between one of setscrews on the base plate and then onto a clean earth point. If the wire is thin enough, it will pass under the distributor cap.
You could use either of the two setscrews illustrated in the photograph to supply the emergency earth.
The brass washer indicated by the arrow is the return earth pick up point, this in turn is laminated via the Bakelite base plate to supply an earth return to the Condenser and C/B points.
The two arrows indicate the earth return points for the Condenser and C/B, also they indicate where a temporary earth feed can be attached.