• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR6 TR6 died/ won't start

Share this page

So got the rotor replaced this morning, and no luck. As far as I can tell I getting power all the way through, but I will have to wait till my assistant ( my wife) comes back from the weekend for me to be able see if I'm getting a spark at the plug. I have been able to check all the wires leading to the coil, which I can see producing spark, and up to the distributor through to the wire. I just don't know for certain of a spark is flying with out seeing it. Thanks for all your help so far, and I'll keep you up to date on what the final issue was.
 
It would seem unlikely that a new rotor would fail immediately -not that it's impossible. Understand this about the rotor: It's purpose is to take the spark from the coil (through the center of the rotor) and pass it along to one of the 6 cylinders that is ready to fire. It's like a rotary switch. Since it is driven by the cam, it should always be in perfect time with the crank, or position of the piston and valves. If you have a good spark from the coil, you should also have a good spark at any of the plugs -assuming the spark is enough to jump that little gap between the edge of the rotor and the conducting bit at the bottom of the cap. Also know that under the cam is a area used to control when to spark. If you had points, there would be 6 lobes to open/close the points at precisely the proper time as the cam rotates. If you have an electronic ignition conversion, there is a plastic piece with 6 magnets (or similar) for the mounted (non moving) sensor to "see". In any case, watching the spark from a wire connected to the coil results is 6 times as many sparks as from the end of the wire -but it should be very close to the same spark. Be sure the distributor is grounded, because that may cause some erratic behavior. Perhaps the sensor has moved or something is intermittent. If you really want to be sure the timing hasn't jumped, rotate the engine by hand until you can no longer hold the pressure (compression) with your finger on #1 cylinder and see if the rotor is pointing at the wire going to that cylinder. If you really want to be sure the wire is sparking, hold onto it while someone else cranks over the engine. You will know it is alive. (I don't recommend you actually do that last thing.)
 
If the coil is producing spark it is after the coil. The H/T wire to the cap; the cap to the post contacting the rotor; the rotor; the cap to the H/T leads to the plugs; the plugs. The most likely for a complete failure in an instant would be the rotor. Possibly not seated completely down on the shaft so it catches on the cap posts and spins on the shaft. Or the shaft is not engaging the dizzy gear.
 
Well, I finally got my issue solved, so I figured I'd share the solution. I ended up replacing the distributor and tore down the old distributor down. The issue ended up being one of the advance weights was loose. This one definitely had me stumped for the longest time, but thanks for all the help.
 
Can you explain what you found wrong with the advance weight? They are supposed to be "loose" and swing outward against springs as the RPM increases. An advance weight problem can significantly effect ignition timing but it should not prevent the spark.

When putting the distributor back together you may have corrected a problem you didn't notice during disassembly.
 
Yes, the weights are a bit loose - especially the one with the heavier spring that doesn't come into play until the RPMS are up aways. A common failure mode for weights is that they get gummed up and stick - sometimes advancing but not returning when the engine idles or stops. I always give the rotor a twist to assure that it snaps back - confirming the weights are freely moving.
 
Instead of saying that one of the advanced weights was loose, I should have said that it wasn't connected properly. It appeared that a small brass pin had snapped and prevented one side of the weights from spinning properly. That is why the rotor would spin, but just not quite at the right time ( I assume).
 
I understand now what you found with the weights.

I was focusing on your fist post where you said you had spark from the coil but not at the plugs. I'm guessing that the malfunctioning advance weight must have thrown the timing way, way out for you not to find spark at the plugs. The rotor position would have to be advanced or retarded significantly for the spark to not jump the gap inside the dizzy cap.
 
Back
Top