hi, i have a 91 305 tpi and while changing my rotor out i noticed a small crack that runs through the star shaped looking piece with the four little rivet like circles in it, the crack runs between the to rivet like circles, meaning that the rivets arent directly affected and the piece still looks secure, is this a bad thing i hope this doesnt mean new distributor, any ideas?

 

I take it your talking about the coil, i really have no clue what your talking about. The only piece that should have rivets in it is the coil. Can you post a pic?

 

hope this picture helps its from auto zone, it the piece thats below the rotor with the 4 rivet looking circles on it inside that thick round housing type part.

 

there is a name for that part it is a balancer and has to do with spark/timing andvance. when the engine revs faster they move oiut and advance the timing or somthing like that. if they are cracked i would hit the yard for a new dist. hate to see what would happen if it came apart while driving. you may also be able to get those from the parts store, not sure on that though.

 

There is no centrifugal advance in that dist; it has nothing to do with the weights that move.

It's the "reluctor". Its purpose is to supply the pulses to the ignition module to tell it when it's time for a spark. It produces a pulse each time the teeth of that "starwheel" line up with the corresponding teeth on the part of the pickup coil that goes around it.

If it's broken, the magnetic field that's present in it will be much weaker than it should, and the pulses will be correspondingly weaker, and the ignition may not "see" them reliably. You could end up with a strange, hard-to-diagnose "mystery" misfire at high speeds especially.

I'd get another one. It's probably cheapest to get a whole dist. Certainly easier that way.

 

So that's the Reluctor... does anyone have a part number for that?

What else should be replaced inside a distributor? Is there anything else that wears out? I'm going to rebuild mine, but I don't know what to buy yet.

 

When I re-do distributors these are the steps I take:

Tear down the distributor. To help get the shaft out use carb cleaner sprayed in from the bottom. It cuts the varnish. Clean housing and related parts.

If the star wheel is badly cracked or loose on the shaft purchase a new shaft assembly from GM.

Check base plate is tight on the housing. If not either weld it or get a new distributor.

Trial fit the shaft and gear checking endplay. Shim to 15 thou of end play (0.015").

Replace pickup coil (new part).

Reseat the original GM ignition module with new heat sink compound. If not a GM module purchase a GM module.

When installing the distributor gear the dimple goes in line with the cut out in the top of the shaft.

Install new rotor and cap.

RBob.

 

relucotr isn't that an ac pick up type and i swear that gm didn't make them look like that. thats kinda odd. could it be a holofex switch. cause that may be it. the gm ac pick up looked a lil diffren't then that. but i'm probaly worng. you'll ne to replace that part. they do sell them at gm dealer ships

 

It's the reluctor.

GM did make it like that. That's how they look.

It's not a Hall Effect switch or sensor (which is a semiconductor device that detects changes in a magnetic field); it's yerbasic inductive magnetic pickup, which is a simple coil of wire, and a permanent magnet, and some iron. The field throught the pickup coil changes as the teeth line up and then move away from each other, and the coil produces a pulse corresponding to the motion of the teeth.