Diagnostic on faulty distributor.........

[richard1]

My 72 Z has a dual point distributor. It is a pain to maintain in tune and it is very hard now to find good point sets. The fiber block wear very fast and I need to adjust the points every 200 miles.

Now I am trying to figure if I have not a distributor problem. The cam lobes are nice, the shaft is tight and doesn't seem to have excessive play. I adjust the points at .020-.022 as per the specs and it is the same on each high point on the lobe. The engine idles fine.

Now if I am at a stop light with the foot on the brake (AT) the engine seems to barely miss a bit as if the fire would not be strong enough. I put on neutral and it idles better but I can still perceive the same miss. If the A/C is on, I feel this miss al ot more.

When I start at the green light, the car is peppy and suddenly at around 2000 RPM it miss once and pick back to normal. I have new points, new rotor, new condenser. The distributor cap and wires have been replaced last year.

Any suggestions?

[john mcgarvie]

Some one installed what i can only describe as a optical censor and it works great.

[blue 72]

Have you checked to see if the vacuum advance is still working?

[richard1]

For now, I just checked some old postings about faulty distributors and I came through a comment in regards of bad electrical contacts at the resistor and coil.

I checked and it seems they needed some cleaning and adjustment of the connectors. I didn't test drive but the engine is idling far better no matter A/C is on or not.

I will follow on the results in a couple of days when I will drive the car on a daily basis for a couple of days to check if everything is fine. We are already close to the 90F here in Vegas. It will be perfect to check everything for the summer time.

[richard1]

There is nothing faulty with the distributor and the vacuum advance is working properly.

The problem was bad (lose) electrical connections at the coil terminals and resistor that cause the random misfire or hiccup at acceleration or at start at stop light.

As some of the regular posters say most of the time.....we all need to remember to start with the inexpensive checks before replacing parts that may be expensive.

At least, this applies to me with a stock ignition.

Richard

[pit crew guy]

Richard do you belong to the Las Vegas SCCA? If not were haveing a two day autocross at the race track this weekend.

[Zforce]

Are you lubing the rubbing block with grease? Without the grease your timing will retard in short order.Mallory sells points lube in a tube (no pun intended) at any good speed shop.

[richard1]

For sure.

[GreenZZZ]

I have a manual transmission which came stock with one set of points. I popped in one of the Mallory distributors and enjoyed lots-n-lots big smile high reving until I smoked my crank bearings! One expensive part leads to another... :stupid:

http://www.centuryperformance.com/mal-4763901-pr-MAL-4763901.html