A rotor failure. What goes wrong?
 

lets start with: 1973.5T/CIS

A few weeks ago I ran a thread on trying to determine what could be the cause of my car running great for the entire day and then just shutting down with no re-start!

I thought it would be that meshed fuel filter in this infamous fuel tank of mine. Others clued as to electrical.

Well, after replacing the fuel filter, re-adjusting the points and even replacing the ignition coil, the car would still not start!!!! By the way the fuel pump and CDI unit were both humming along. I had one more idea that I thought would be nuts but worth a try and that was to replace that huge rev limiter rotor with a spare regulator rotor I had on hand. Simple enough.

After replacing the rotor it started right up!!!! WHAT? That huge limiter rotor somehow malfunctioned. But just how and why? What could possibly go wrong with these to shut down the electrical flow to the distributor? Anyone?

Bob

rotor
 

The contact or spring broke inside or the glue came loose.
Just a guess.

Thanks.

I do not know what the internals look under that black sealant. I have seen this part of the rotor crack over time, but what could have caused this failure I am not sure. You cannot dissect these things! I never did like these and I wonder if they truly work! My preference is to stay with the simple rotor. I do not race my car nor take it up to redline.

What I learned here is start with the simple stuff (points, rotor , cap). Now I will carry spares of all three when heading out.

May have a crack that allows the spark to ground to the shaft.

Thanks John.

I can only assume that these have a limited life span given their susceptibility to heat.

Remove dizzy after TDC to check for up/down slop on the gear. Your shims/washers/bearings may have disintegrated

I believe that the rotor is the weak point in the system to avoid damage to more expensive components. It does it's job by failing when there is an issue with arcing etc.

When you replace your rotor check your pugs, wires, grounds etc. to ensure that they are all in working order.

if it is a resistor rotor the resistor can open.

okay, so the car started right up and I revved up to 5500 rpm a few times before going for a road test. No sooner then I drove a block away on higher acceleration it broke up a bit on me. I immediately drove back to my garage. It was fine while at idle, but under load it just was not 100%. NOW WHAT? Reset points? Ignition wires? I do not where to start actually.

bob

coil.
perhaps the wire frmo the CD to the points. the insulation can crack.
check timing to see if the advance is working.
you can get a non-rev limiter rotor from advance and stick in there.
points gap is not critical. make sure they are opening and closing.


check how it revs when cold vs hot. the coil can break down when it gets hot.

Thanks.

I changed out the coil the same time I replace the rotor. I switched to the MSD Blaster coil after having two of the expensive Bosch coils fail on me. When I ran a thread about these Bosch coils which got a lot of feedback, many recommended the less expensive MSD Blaster coil, sufficient to do the job on my 1973.5T. I have been using this coil for over five years now with no issues. I changed it out with a new one the other day to freshen up the system. Heck, it only cost $59!!!!!

I think my issue might be one of many and that is what I had about these older cars. It can be my mesh filter in the fuel tank, wiring from distributor to CDI, timing, distributor, WUR, etc, etc. NUTS!!!!!!!!!!!!!!!!


Bob

if you think it is fuel check the fuel pump flow pressure and volume.

Might be the internal mesh filter. See my post on CIS TANKS................

my rotor failed last Fall while diagnosing my No-Start problem after total engine rebuild (long story, continuing right now). I finally was able to diagnose the failed rotor. My guess is that these types of rotors cannot handle the MSD ignition system. It was the large rotor w/ redline safety gizmo. I dremeled out the epoxy and soldered in some 12 gauge wire. I added some fresh black epoxy to cover the repair. It fires up now. We'll see if it works long term as I think I have my air/fuel issues sorted out.