RE: More on Marelliplex

[Hirsch <Catenary@domain.elided>]

Hi Bob,

> I found the time last night to run the tests on my
> Marelliplex ignition. Everything was fine, except the
> coil resistance measurements. Here's what I found:
 =

> resistance between coil terminals:
>    1.2 ohm  (0.69-0.75 per Centerline Cat.)
> resistance between coil output wire and terminal:
>    6800 ohm (7100-8700 ohm per Centerline Cat.)
 =

> Anyone with a good Marelliplex system willing to
> take some measurements?

I have two spare Marelliplex units that are in good
working order. Measurements are as follows:

resistance between coil terminals:
1) 0.84 ohms
2) 0.76 ohms

resistance between coil output wire and terminal:
1) 7.45k ohms
2) 7.43k ohms

I don't think your measurements are off enough to
indicate a bad coil. Resistance values under one
ohm are hard to measure accurately.

Questions: Does an inductive timing light fire
well on all four plug wires? I've found that
sometimes a bad wire will cause the timing light
to miss-fire and identify the problem cylinder.
Of course, if the coil or something else upstream
is bad, all cylinders should cause the light to miss-fire.

I assume you checked the ign. wires with an ohmmeter
and changed the disty cap.

One common problem with the MarelliPlex is that the
wire insulation inside the disty near the pickup unit
cracks and the wire corodes. I'd check this carefully.

If the Plex unit is bad, I'd look at another elect.
ignition like the Crane Cams XR-700 with Bosch Blue
coil and an old dity or one of the hi-perf units
advertised in the Alfa Owner.

Good luck,

Rich Hirsch
St Louis MO. USA

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