How would I know if my dizzy needs rebuilding?
 

1979 SC w/80k.

How can I tell if my dizzy needs to be rebuilt?

I plan on changing out the fuel system this year from CIS to PMO or EFI (undecided) and want to make sure the ignition is up to par so I can remove it from the tuning equation. I'm sure there will be some timing adjustments to be made but want a good ignition in place before hand.

I do understand that a recurve may be needed but I would like to go with CDI+ so I'm thinking a recurve won't be needed.

Also, if it does need to be rebuilt, are there any recommendations?

Thanks,

If it’s an original 43 year old distributor it should be rebuilt.
I sent mine to Jerry Woods (look up JWE Porsche) and he will rebuild and recurve it.
I did this 2 years ago and I also did the CDI+… but I don’t use the electronic ignition part.
The CDI+ is great.
You would not do a recurve if you are going to “lockout” the Distributor and use the programmable.

The correct way (assuming the engine is running) is to look at the primary pattern on an automotive oscilloscope and watch the variations in the pattern.

Short of having an automotive scope, check the radial play in the bearings.

So a 44 year old car with just 80,000 miles. Only 1,888 miles per year. The poor thing wants to be driven!

Has it been stored for a long period, or driven some each year?

Pop off the cap, and the rotor, is the grease in there still something that moves around or has it turned to rock?

I would recommend at the least rotate the engine to TDC 1 and line the rotor up to the mark and pull the distributor to replace the o-ring. And then check out the condition of the distributor carefully.

Gotcha, thank you!

Well, I don't have on of those and don't want to spend the money, I'd just go ahead and rebuild it.

I bought the car a little over a year ago and drive it a couple times a week at least, I've put about 4k on it in the last year and that had downtime for trans repairs and a few other things. :)

There's "rebuild," and there's "clean and lube." Put a timing light on it. If the timing is steady at low and high RPM, then it doesn't need a rebuild.

With 88kmi, I'd think you only need to clean and lube. See other threads here for how to do that. It's not difficult.

I was referring to having a shop check it on their scope. But short of that, put the inductive lead of your timing light on the coil lead (instead of #1) and see how much the timing jumps around Z1, Z2, and Z3.

I know what you meant, I meant not paying a shop to see if my dizzy is good, I'm willing to bet the amount of money that would cost would be comparable to just having the dizzy rebuilt. :)

What is the cost?
What is the down time?

Rich

I did look up JWE but haven't called them yet, probably will today or monday. I'm not in a hurry as my ignition seems fine right now, I'm just preparing for future plans which hopefully will be late summer this year.

"If it ain't broke, don't fix it!"

I agree, however with nothing to compare it too, I don't know if it's up to par.

Do you know if your engine is up to par? Do you think you should rebuild it just to be sure? If you're just looking for things to rebuild, I can give you a really long list! ;)

I'll say it again: Put a timing light on it and see if the timing is steady. Also using the timing light, check that the vacuum advance and centrifugal advance operate. That's all you need to do.

You can tell a lot by looking at the contacts on the inside of the distributor cap. If it all looks pretty clean with minimal and even wear on the electrical contacts (where the rotor hits), it's probably fine.

Having been around these cars for going on 40 years, I'm confident that, absent an unbroken chain of service records, the only thing a mechanical odometer on an air cooled Porsche can tell you is the absolute *minimum* amount of miles that are on the car (and an unbroken chain of records isn't necessarily foolproof). There's a better than average chance that a given 911 has more miles on it than indicated. Jus' sayin'.

Nathan Merz is "astounded" [sarcasm] by how many "85k mile" 3.2 Carreras there are out there (if I recall correctly, he conveys that sentiment in his PCA 3.2 overview video). Most of these cars were daily drivers back in the day.

Anywho, not necessarily germaine to the OP's question, but a reality of these cars that owners, especially those unfamiliar with the typical foibles, should be intellectually honest about.

Well, the PPI showed the engine to be in great shape, there was a recent top end done, and compression was 2-3% across the board. I actually do plan on rebuilding most everything, I love to work on my cars and I want them to be mechanically sound. I do know what you were trying to convey though, it can be a never ending process. :)

Not long after buying the car, I did cap/rotor/plugs and wires, the cap/rotor were in terrible shape and the car ran worlds better after the tune up.

Yep, I agree with this statement.

If you go EFI, you'll probably want a crank trigger fired by the ECU anyway...

Depending on the cost of rebuilding the distributor, you might just want to go with a programmable one from 123ignition.