DUAL POINTS TO SINGLE POINTS

[manoa matt]

I got a 78 spider with dual points, standard 12volt coil with external resistor. After my engine overhaull I tried to get the car started with the dual points set up, which proved difficult. I then switched to the single points set up as described in the IAP tech pages. The car started up and had a very low idle. I think my coil and resistor are origional, or just very old. The coil tests ok but I think i will replace it with a new coil that has an internal resistor.

After looking through the vick autosport catalogue I came across a Ballast resistor, item # 19-1600, on page 21. the description is as follows: An essential electrical item for very early spiders, 850's and all spider dual point distributors that have been converted to single points.

Question: If my new coil has an internal resistor, and my distributior has new points and condensor, what is this ballast resistor, and what does it do? Do i actually need it? IAP says nothing about it.

matt

[So Cal Mark]

with an internal resistor coil you shouldn't need the ballast resistor. Have you set the timing yet? There is about 5 degree timing difference in the two sets of points, so you may be running more retarded than previously.
An old coil shouldn't cause a low idle, ignition faults are pronounced under load so they usually show up when accelerating

[manoa matt]

Mark,

Let me see if I got this right.

With dual points: One set of points is the starting points, and they provide 10 deg. advance timming, untill the car warms up, then it switches over to the running points which provide 0 deg.
timming.

With single points: You basically just have running points, their gap is set to running points specs. But you set timming to 10 deg. BTDC.


Why would the timming be set 10deg. advance when typically the running points are set at 0 deg. ?

[So Cal Mark]

easier starting with the timing advanced, lower emissions with the timing at 0