8BA distributor will not make spark

J

JHFORD51

Senior Member
My recently overhauled aluminum 0BA distributor won't spark. I sent it off and had it rebuilt while I was doing the rest of the engine. Here's what DOES work:

Cap and rotor
Condenser
Plug wires
Plugs
Coil
Hot wire to coil
Lead wire to distributor
High tension coil wire

Put a spare distributor in engine using all these same parts and she fires right up.

I have continuity to the dist body where I would expect it and isolation of the lead in wire to the points as I would expect.

I'm sure it ran fine on the distributor machine but I sure can't make it work. Any suggestions?
 
lousy ground between the points and the mount plate--at least that is what happened to me==cleaned off bottom of points and advance plate where they mount and made sure the wire from the advance plate to distributor has a good ground
 
That's about what I thought too, even though it showed continuity on the DMM. So, I:

Burnished the dist body in the clamping pad area to remove the clear coat
Removed points and dremeled off the black paint from the advance plate
Same thing under condenser case mount
Inspected the bakelite insulator from the lead in wire stud-- all good there
Put a dab of liquid electric tape between the lead in stud to power wire and case body junction just to "beef up" the existing insulator.

Still no spark.

Next step is points swap and or just rewire the dumb thing...a little frustrating to do all this on a fresh rebuild. Besides the bushing renewal, I'm essentially rebuilding the rebuild.
 
Put a 12 volt test light from the terminal on the distributor to the coil and ground. Turn the engine over; does the light go off and on?
 
Measure the voltage on the Negative side with the ignition on, should be around 6V.
Then measure the voltage with the point open , on the point that is connected to the plus side of the coil.
If you have around 6V.
Then try this.

Take an ignition cable with a spark plug, put in the coil and ground the spark plug.
Set the distributor so the points are open.
Turn on the ignition.
Short the point with a small screwdriver for a second or two, and when you release screwdriver you should get a spark.

If you get a weak yellow spark, the condenser is the usual suspect.
Even new ones can be bad, or old NOS ones.

If you dont get a spark at all i would take a look at the coil.
 
Wanted to close the loop on this.

Swapped flexible ground strap, no change.

Replaced lead in wire, stud, and insulated power wire to points with a later model one piece assembly (eliminates a failure point). No change.

Noticed I had more resistance at the rivet holding the points together than anywhere else in the grounding circuit.

Swapped the new GP branded points for a set of NOS Ford points and it fired right up.

So, too much paint interfering with grounding and a bad set of points. Circuit had continuity but couldn't flow any current...
 
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