When I bought the car there was nothing wrong with it. Its beed running super. One day I started the car and it idled low.. very low. 500 to be exact. It had me wondering because I thought that I had blown a seal someware. I decied to change the cap and rotor. When I took the cap off peices of the rotor fell everyware! ok I thought,, just needs a new rotor and cap. I bought both they came out to 25 buks. Now its been about 3 weeks since that happend. Now I started the car up and bam there it is again slow idle at 500. I didn't want to check under the cap but I have the hanes book and was going to try to adjust the timeing anyway. When I took the cap off I found that the rotor was hitting the cap and one of the "legs" on the rotor was about to break off. I took pics with my phone and now I am here looking for a solution. I did searches under distributer cap rotor broken.. nothing usefull came out. If anyone has any idea as to what could have caused this problem please let me know as soon as possible, thanks.

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___________________

-----> drunkclever <-----

 

Just speaking from personal experience, sometimes its hard to line up the cap correctly. It's very easy to get it on crooked, and it looks like it's on straight. When that happens, the rotor will hit one of the "pegs" and break one or the other. I just try to be very careful when replacing the cap, then visually inspect it just to make sure...

 

this cap was in use with the car for about 2 weeks then it just gave out. If there was some sort of alinement problem wouldn't it have bent the few times it went around?

 

I would agree that it's unusual tha it ran fine for 2 weeks, but nonetheless, you have a broken rotor and your car is not going to be timed correctly until you replace it.

The Cap and Rotor system is just a means of getting the spark to fire when the eccentric shaft is in the right position. You're translating the rotational position of the combustion rotors onto a piece of plastic about 2" in width which spins inside a cylinder about 4" in diameter. This has the effect that any small change in position of these contacts will cause a huge impact to the firing of the spark. It's much more than just a few degrees of timing when a part gets broken or bent.

I would recommend taking a good look at the rotor and cap and ensure that they are properly formed and fit correctly. Could be that you just got a bad part and the internal alignment was such that they impacted at some point. You might also want to check the security of the 'clips' that hold the Cap in place - if one of these came off unexpectedly, it could cause the cap to come up, quickly getting whacked by the rotor and there you are...

Clean off any oil or grease which could be lubricating those metal clips and then have at it again. HTH, and reply back if you think something else is wrong.

 

ok cleaned everything, checked the distributor for play, humm.. is there suppose to be a certain level of play on the distributor? It seems as though the timeing for the trailing plugs had moved.. ohh oh. I guess I am going to have to find someone to retime it; or atleast check the timeing.

I think I am going to looking into getting some type of direct ignition system so I don't have to worry about this happening while I am coasting around town. (hondas and nissans at every red light just want to test their new cold air intakes, they think they still have a shot..lol ) not that I condone street raceing.. they just make me laugh!

 

The distributor should not be able to move when you twist it (obviously), because this will affect change in both leading and trailing ignition timing. If you can take the cap and rotate it at all - you need to torque down the 12mm bolt at the base of the distributor where it mounts to the front cover. This is AFTER you have timed it properly, of course.

Where the cap mounts to the distributor, there are 2 metal clips at 180 deg from each other which snap into place on the cap. These should not allow any play at all in the cap. If you can lift the cap on one side or the other, you need to find out why - this is what's causing the interference to the rotor on the inside.

Leading ignition is set through the 12mm bolt at the base of the distributor. Training ignition is set through a Phillips-head screw on the outside of the distributor where the vacuum pot is located. By loosening the screw and then pushing the pot in or out will alter trailing ignition in relation to leading. This assumes that you have stock vacuum trailing advance. Vacuum advanced trailing helps to shorten the gap cycle between leading and trailing so that the engine gets a good spark while the A/F is at maximum compression.

Sounds like you might have found your problem.

 

Junk that metal dust cap and you wont have anymore problem. In fact, I cant even remember when i ditched mine. Too many years ago.