CA77 points arcing

mustanger · Post by **mustanger** » Thu Sep 25, 2008 1:35 pm

Dear Dreamers

I've been wrestling all summer to get a 305 running like it did last year. Some of you have read my post on the carburetion problem. While working on that I had the contact points cover off and noticed that when cranking the engine, there was arcing between the points. I've read earlier posts on this subject and I've changed the condenser (with a new one), changed the points (with points from a CA72 that is runnig well and has no arcing between its points) and changed the coil ( with another I got off ebay and was pulled from a running bike) . Obviously, nothing got rid of the arcing or I wouldn't be writing this. The bike is capable of running but the arcing can't be doing any good. Does anybody have any suggestions?

I'm also wondering about the circuitry of this condenser. My 66 Mustang has a condenser that has a wire going to the points and it the bodyof the condenser is screwed into the distributor where it's grounded. As we know the 305 condenser has two wires, one leading to the ponts and a second one connecting to a 12V hot wire. Why is it different in a car?

kustommusic · Post by **kustommusic** » Thu Sep 25, 2008 8:50 pm

Mustanger, Has anyone mentioned yet that is normal for points to arc some? Back "in da day" we used to put clear distributor caps on our cars just so we could see the pretty sparks.
As far as your condenser hook up compared to your Mustang it really is the same. In your car the condenser picks up the voltage at the points,in your bike the condenser picks it up at the coil. The thing is, it just looks different. I think you should make sure you have good grounds at the coil and condenser, and engine to frame. Good Luck,Kustommusic

byrdman76 · Post by **byrdman76** » Fri Sep 26, 2008 8:24 am

I recently had the same problem on my Superhawk. I had painted my frame and coil holders during a restoration. I went through the entire circuit for grounds and did all the tricks with cleaning the points and such. It came down that the fact that the coil had to be grounded to the frame. I had to remove all of the paint on the inside of the coil holder and where the holder bolted to the frame. I found this out by taking a wire mounted to the negative terminal on the battery and then touched the ignition system where I felt it needed to be properly grounded. With the bike running I kept changing the position of the wire to different areas. As soon as I touched the one coil that I was having a problem with the arching went away.

It worked for me hopefully it will work for you.

mustanger · Post by **mustanger** » Fri Sep 26, 2008 9:09 am

I read your post, byrdman, before I put in this post and I already examined the grounding of the coil. I ran a wire from the negative terminal of the battery and touched it to various places on the coil mount and found nothing that would get rid of the arcing. I also used a volt meter to test for a 12V potential by touching the negative lead to those parts of the frame. All the tests indicated I have a good ground of the coil. I haven't painted the bike as you did. However, I didn't understand exactly how you did your ground wire testing. What did you mean by "touched the one coil that was having a problem with arcing" ? The coil is housed in plastic and the only metal part is the mount which I assume is connected to the inside of the coil in a way to bring it to ground. What exactly is the part of the bike where you touched the ground wire to bring the coil to ground?

And thanks, Kustomusic, for mentioning that it might be normal. I don't even know if the arcing has anything to do with the running problems I've been having all summer. The points may have been arcing last summer when the bike ran great. I just happened to notice it because I had the points cover off in dealing with what I assume are carburation problems. It bothered me because my CA72 which runs fine doesn't arc.

It's a moot point but I didn't understand your sentence "In your car the condenser picks up the voltage at the points,in your bike the condenser picks it up at the coil." If you or anyone else wants to try and explain this to a dumb redneck I'd sure take the time to read it.

e3steve · Post by **e3steve** » Fri Sep 26, 2008 12:14 pm

I'm also wondering about the circuitry of this condenser. My 66 Mustang has a condenser that has a wire going to the points and it the bodyof the condenser is screwed into the distributor where it's grounded. As we know the 305 condenser has two wires, one leading to the ponts and a second one connecting to a 12V hot wire. Why is it different in a car?

Uh uh! The condenser is an electrolytic capacitor. The points allow the coil to charge magnetically and then, when they open, the magnetic field collapses and a high (20KV or more) voltage is produced within the coil (inductor). The capacitor is used to absorb the back EMF (Electro-Magnetic Force) from the magnetic field in the coil and minimizes points burning thus maximizing the points' life. The CB's type-1 dual condenser -- one for each set of points (contact set) -- is connected at the coils (can't comment on a type-2 motor). It can be connected anywhere in the ignition's LT (Low Tension) -ve circuit that is convenient to the system, mechanically-speaking. Hence the CB has it's condenser(s) mounted alongside the coils and the -ve ccts' legs are 'sent' to ground via the contact sets via a long, heat-resistant-material-covered pair of wires.

Most car manufacturers used to fit the condenser on the distrubutor itself. Any conventional traditional coil/contact set ignition system requires one condenser for one coil for one set of contacts (points).