distributor cap/rotor alignment, '87

[rwingnut]

Experiencing an occasional cut-out and started some electrical trouble shooting. Inspected the distributor cap and noticed that the bottom ~3/32" of the contacts are charred and pitted. The remaining portion of the contacts are like new. The rotor and cap have ~25k miles. Are there shims that can raise the relative height of the rotor in relation to the cap to try and get the rotor closer to the center of the contacts?

Is this the right approach or am I over looking something? 25k miles doesn't seem like much for this unit.

Thanks

[Chuck Moreland]

Originally posted by rwingnut

Is this the right approach or am I over looking something? 25k miles doesn't seem like much for this unit.

Thanks

I'd say you got your money's worth. Get a new cap and rotor and don't mess around.

Don't overlook the routine maintenance items, they will bite you - I promise. Fuel filter, cap, rotor, plugs, points, oil and filter, air filter, valve adjust, clutch adjust - do them all once a year. More if you drive a lot of miles.

Trying to squeeze the last ounce of life from these items is false economy. Your car will perform poorly and you will end up chasing down seemingly big problems that have these basic causes (or paying someone else to do it for you). You might even get stranded roadside. Easily avoided.

[rwingnut]

I think my question was ambiguous. I agree, there is no reason to try to stretch more miles out of a questionable piece. The cap and rotor were replaced.

My question is wether 25k miles is typical. If 25k miles is not typical, could misalignment between cap and rotor cause an arching that causes premature pitting. If 25k miles is typical, then no worries.

Thanks

[twin plugged targa]

Randy-
This may be way off base, but i had a persistant problem which wore out dist. caps.
The shims on the distributor were out and the end play was off. Everything was fine when the engine was cold but when it had warmed up when I accelerated hard the dist. would shoot upwards and destroy the rotor or wear the cap!.
It is relatively easy to remove the distributor and check the end play. I forget how right now but maybe some of these other guys can help. There may be stuff on the search function.
My 02 cents would be to remove the dist. and inspect it.
I did- finally after 3-4 weeks of checking the whole ignition system etc and finally posted a pic here and the guys helped me identify the problem!.
Worth a try!
Hope this helps in some way
regards
ben

[Rot 911]

Originally posted by rwingnut
My question is wether 25k miles is typical. If 25k miles is not typical, could misalignment between cap and rotor cause an arching that causes premature pitting. If 25k miles is typical, then no worries. [/B]

The way the spark gets to your spark plugs is by an electrical arc that goes from the rotor to the cap. This inevitably leads to pitting on the cap. I would never leave the same rotor and cap on my engine for 25,000 miles. I change mine every 10,000 or every year which ever comes first. Same for all the other items Chuck mentioned. He is giving you good advice. Take it.

[Tim Polzin]

After chasing a poor running condition on my 86, Chuck's words could not be more true. In my case, the end of the rotor had burned right off with heavy pitting of the cap. I'm surprised it ran at all. The date code on the rotor was still from 86. If it was original, that would mean it travelled more than 195,000 miles!

This car was serviced regularily by the previous owner at a Porsche dealer and a major Porsche shop. Interesting that this part was skipped.

One last thing, there is a small circlip below the felt. If the shaft has been pulled up and clip is not attached, the top shaft will have excessive end float.

Tim