Exhaust "popping" on overrun?

[Ian Williams]

In DK4 distributors I have rebuilt the thing which affected the working of advance mech most was not so much weak springs but wear in the spring mounting eye on the toggle. I fill and re drill these, rebore the toggle if the swivel hole is worn, and fit new or oversize pins on the cams and base plates. There are a number of DK4 variants all with different amounts of total advance, this is controlled by a hole on the base plate, these can also be worn increasing amount of total advance. I you have a selection of old units then you can take say a 4 degree baseplate with a 1/4" hole and open it out to 21/64 which will give you 8 degrees, or to 3/8" which will give you 10 degrees. If keen you could also turn up a top hat insert for the base plate to reduce the total advance.
Note; the figures are distributor degrees rather than crank degrees.