distributor cap fouled???

kmarccoco · #1 (**permalink**) 08-12-2006, 05:13 PM

today i pulled my msd distributor cap off. i did so to try to track an idle problem ive been having. i looked at the inside of the cap and found that the contacts were pretty badly corroded. the posts were covered with a greenish/copper pitting. ast was the rotor.. its fairly new, only 1000 k. i imagine this is not normal. can i just clean them? what caused this???

thanks ..
ken

Excaliber · #2 (**permalink**) 08-12-2006, 06:00 PM

Fairly common. Main issue is the vent (or lack thereof) is blocked. Some caps dont have a vent, they NEED one.

kmarccoco · #3 (**permalink**) 08-12-2006, 06:29 PM

should i clean the posts? theyre pretty pitted. or replace cap. this condition would cause bad performance right??

wtm442 · #4 (**permalink**) 08-12-2006, 07:02 PM

You could try to clean the contacts but I would replace the cap AND the rotor.

The cause is corrosion due to moisture.

kmarccoco · #5 (**permalink**) 08-12-2006, 07:21 PM

i cleaned the posts, couldn't get behind them very well. there was a slight sign of moisture in the cap. i'll take it for a test spin.

Tom Kirkham · #6 (**permalink**) 08-12-2006, 09:21 PM

You need to make sure that the polarity of your distributer is correct. MSD has had problems in the past with their distributers being wired backwards. If the phasing is incorrect the spark will fire between the terminal posts. This will chew up the inside of the cap becouse of the excessive voltage required to make the jump.

The easy way to check is to bring your engine up to the timing mark. Probably around 12 degrees BTDC. Remove your distributer cap and see where the rotor is pointing. The rotor should be pointing very close to the terminal it should be firing at. If not you have found your problem and will need to revese the wires on distributer or spark box. You will also need to retime your engine.

Hope this helps.

kmarccoco · #7 (**permalink**) 08-12-2006, 11:32 PM

thanks for the help guys. Tom thanks for that interesting tip. i will check that tomorrow...

CobERA · #8 (**permalink**) 08-14-2006, 02:54 PM

Ken,

I had the same problem. I assume you have an MSD brand cap. I had two MSD caps foul up as you described.

I replaced the MSD brand with a generic brand from the local auto parts place and have not had a problem since.

Don't know what the problem is with the MSD caps, but another Cobra owner I know had the same issue and resolution.

Carnut427 · #9 (**permalink**) 08-15-2006, 12:22 AM

I recently replaced my Accel cap & rotor, looked at others including the MSD and wasn't impressed with any others at all...aluminum contacts instead of brass??? I put in another Accel.

Dan