dancing guages

[s-man]

Recently have encountered a mysterious dance of the guages. It seemed to coincide after the installation of an optical trigger for my ignition, but I don't know if I can lay blame there.

I have a 1973 "S" Targa, bone stock except for the new optical trigger. The oil temp/pressure seem to bounce in harmony, while the tach does as well at idle. I beleive there is also a miss in the exhaust note present, so I am inclined to lean towards ignition. Above idle, all the guages settle down, yet I knwo I still have the all persistant "MFI-MISS".

I am curious as to any suggestions, if anyone has had any similar experience, please help.What I do know is that "CRane" does maintain that the optical trigger may not be read by early Porsche tachs, hence the tachs bounce at idle but fine above.

My wires are good, plugs good, coil good, CDI box works, have been on the ground test loop many times, and I have a clean car. I am wondering if the "VOLTAGE REGULATOR" can be playing a role in the scheme of things, or the alternator.

I have good batteries, never go flatt.....

Cheers!@!!!

[Early_S_Man]

Does your alternator warning lamp ever flicker or come on at idle?

What does your system Voltage read with an analog multimeter at idle, and above 2000 rpm, and is there any 'dancing' of the analog Voltmeter reading at idle?

If the Voltsge regulator is ald and contacts are pitted ... it may be causing the problem, but so can worn brushes ...

If Voltage dropouts are occuring, I suggest installing a 5 Watt 68 Ohm resistor in parallel with the alternator warning lamp bulb -- just solder it right to the bulb holder terminals. The resistor will lower the 'Zero-Ampere alternator rpm' that can cause the warning lamp at idle speeds.

There is no such thing as an MFI-miss! You have ignition problems, not MFI problems! Have you removed your distributor and cleaned it, and checked for excessive bushing wear and play in the distributor shaft? Worn bushings can cause a 'timing scatter' that optical triggers won't cure!!! And, apparently your Crane trigger 'upgrade' gave no improvements at all!

Read the following thread and do ALL of the checks!

http://forums.pelicanparts.com/showthread.php?threadid=5432&highlight=distributor+lube

[pwd72s]

Warren, I'd never question your electrical expertise. Just adding my 2 cents (or less, after the Friday market!) worth. My most trusted mechanic told me that he could never make a pointless ignition (think he was mentioning pertronix) work well in HIS '73S.
Any further thoughts? Paul

[s-man]

Warren, I have no warning light issues. I certainly cannot understrand why you claim that a poorly adjusted mfi does not affect the combustion process and a resulting poor or incomplete burn. Maybe I identified it incorrectly as a miss, my apologies.

As for the timing scatter, could you elaborate on this. I have had the dist. out on more that one ocassion, axial play seems ok, breaker plate, ok, vacuum port ok. I may be inclined to remove it once again.

The car pulls well, right up to 6000 rpm, havn't been past there much, no need, plently of balls right there.

My timing at idle is rock solid, and when brought to 5000 is at 30%, 6000 35% app. The only irregularity I seem to feel is as I near 5000 or above in the advance curve test, the engine seems to drop of or seem to flat spot, or go into a simulated overrun or limiting scenaro....

At any rate, I look forward to your further comments.