Hello,

I have a 1988 Mazda 323 non-turbo. Recently, I discovered that the two
vacuum servo sections on the distributor both had leaks. I searched,
but was not able to find a replacement ("Vac-Set"). So, I replaced the
entire distributor with a rebuilt Cardone one from Summit Racing. I
believed Cardone was a quality rebuilder.

The rebuilt distributor looked fine, but I checked the vacuum servo for
leaks anyway. It was good as well. I installed the distributor and
verified the vacuum advance as outlined in the shop manual. Problem
solved and the car ran fine.

After almost 3 months, I noticed the return of some of the same
symptoms that I had before the repair. So, I checked the vacuum
advance servo for leaks, and sure enough, both sections were leaking
again.

So, at 96 days after my purchase, I notified both Summit Racing, and
Cardone of the failure. Both said that the warranty was 90 days and
Summit offered to sell me a new distributor.

I have decided to rebuild the vacuum servo myself. The problem is that
I returned the core after I felt the problem was fixed and I would
prefer not to have the pressure of taking the Mazda out of service. It
is a daily driver.

If anyone has a junk distributor in any condition that you would be
willing to send me at my expense I would appreciate it.

Thanks,
Michael -- Phoenix, Arizona, USA

 

I don't know how you intend to rebuild the vacuum advance unit but good luck. If it were me in the intrim till you get one block off the vacuum hose and drive it. The vacuum advance improves fuel economy under light throttle and plays no part in maximum power. Many aftermarket distributors for early Ford's and Chevy's didnt have one.

 

Charlescrown,

Thank you for your reply.

I know that re-building a vacuum servo is a challenge.

I believe one servo section is used by ported vacuum to retard the spark at idle to clean up emissions. In Arizona this car is still required to pass a yearly emission test. There is a good chance that it will fail without the servo working. I am trying to avoid losing the use of the car because of such a simple failure.

Mike

 

Yea the added diaphragm retards the timing so a wider throttle opening is needed to maintain idle and also on overrun when deceratting. Better atomisation of the fuel under those conditions. Bit of a farce considering how much emissions it actually reduces. At that age you could possibly retard the timing by a few degrees and open the idle speed screw to pass an emission test. Do they put your car on a dyno to check emissions or just a tailpipe read?
I see AI has a different point of view.

 

Charlescrown,

Thank you for confirming my thoughts.

Arizona does the test on a dynamometer and it includes an idle no load test of about 1 minute.

I could still buy another re-built distributor for about $100, but why should I expect different results? I expect that the vacuum servo is NOS and after 30 years the diaphragm is just too old. I thought that maybe some manufacturer thought about this and has an electronic ignition module that would work with a vintage car to simulate the vacuum advance. But, I didn't find any. Then I thought that I might build such a thing myself as a hobby project. While I have the skills to do that, the job is a lot bigger than rebuilding the Vac-Set.

I have 6 months until the next emission test. Failing the test with a simple problem to fix isn't a big deal. But, failing the test and not being able to fix the problem in a couple of weeks becomes a big deal and I think that I would just junk the car at that point.

I'd really just like to keep the car on the road ... I've had it since new. I'm open to other ideas, but not tuning the car just to pass the emission test. That would make me as bad as Volkswagen.

Mike

 

Volkswago were very clever how they did it. On a dyno the car passed but on the road with input from the steering was another story. Cost them big time.
This one may be what your looking for.
https://www.thewrenchmonkey.ca/auto-...acuum-advance/

 

Charlescrown,

Thanks once more. Your reply got me off dead center.

Neither of the Vac-Sets that you pointed to are in stock. But that reminded me of the search that I did last time when I couldn't find one. At that time most places showed the part as no longer available. Some dealers showed it available so I ordered from one of them. Then they cancelled the order as "part no longer available." So I tried a different dealer with the same result. I gave up trying dealers, especially since their websites looked very similar, and therefore I ended up ordering a whole rebuilt distributor.

My search today was much the same, except a few Vac-Sets came up on ebay. I ordered one for $60 expecting the order to fail since the ebay listing was by yet another dealer. But, the purchase was confirmed. I think that I'll actually get this one.

Thanks again,
Mike

 

Having a collection of older cars I can appreciate what your going thru. Good luck with the ebay. purchase.