Marelli Plex Information - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 4 (permalink) Old 07-08-2019, 01:12 PM Thread Starter
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Marelli Plex Information

Hi All,

I was taking a closer look at an extra Plex unit before pulling the one in my 1981 Spider. I like the opportunity to understand something before I dive it. But of course it led to some additional questions. Maybe someone could help with some previous knowledge.

Fortunately, the unit in hand is in pretty good condition if the one that comes out is not. The bushings have no play. However, I want to understand the following:

1. The advance weights pivot on the pins. The wear I can see in the pins seems very small. Yet the weights seem loose as I can rock them on the pins. How loose or tight should the weights be on the pins? If need be I could make up new pins on the lathe.

2. I have read about spring replacement here on the BB about using GM HEI spring kits. I picked a kit up but I have to say they don't look very much the same. Is there either a source for the original springs or ones that are superior to the GM kit that you may know of?

3. Last but not least both weights have a small hole right on the edge. One of the weights has a plastic tube and the other has the hole without the tube. I can see the tube makes contact first when the weights come back into a rest position. I assume that they are cushions. Is this their function? This one is just a curiosity question as I will make the missing tube.

Thanks to all for any information you can share.

Have a great summer evening.

Todd

Happymotoring

Ď81 Spider
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post #2 of 4 (permalink) Old 07-14-2019, 09:42 PM
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Hmmm

Crickets...

Have you considered posting in an appropriate technical Forum?

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #3 of 4 (permalink) Old 07-14-2019, 09:58 PM
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Hmmm

Crickets...

Have you considered posting in an appropriate technical Forum?

Steve Waclo Carson City, NV; '87 Spider QV, ES Champion, 2018 Reno SCCA (125k);'93 Honda Nighthawk 750 (105k);'03 GMC Sierra SLE 2500HD Turbo Diesel (155k);'08 Altima Coupe 3.5SE, 6sp (125k)
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post #4 of 4 (permalink) Old 07-15-2019, 08:35 AM
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I have a photo showing my 'Plex fitted with a stock spring and a very light weight spring. This allow for full advance at about 3k rpm.

https://www.alfabb.com/bb/forums/ele...lex-photo.html

Jim . . . '72 Super 1300, '70, 1750GTV, 2nd series,
'62, Lancia Flaminia Zagato3c, 2nd series
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