Technical 850 electronic igniton

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Technical 850 electronic igniton

hairgoneJohn

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i folks

I've got an 850 spider (1973) that has been imported from the States.

It has an electronic ignition system comprising a rotor and pickup in the distributor and a module on the rear bulkhead. I think that the module might be failing when hot and would like to change it.

The module is a GM unit with 466 moulded on it and it is then overprinted in white with Magnetti Marelli 0D09.

An ignition parts specialist supplied me with a new module but the engine is difficult to start with it, won't idle properly and dies when the accelarator is pressed.
I have been told that this replacement module is a universal unit and that they are all the same. This does not appear to be the case.

I cannot find any reference to Magnetti Marelli 0D09 on the web. Can anyone shed any light please?
 
A google search for GM ignition module no. 466 shows lots of info on testing it.

Your cold starting/running problems sound like what happens when the ignition is retarded. US models used 0 or 5 degrees btdc at idle, European models used 10 degrees btdc.

Some of the US models (both dual points and electronic ignition) had a facility whereby the ignition timing was advanced to 10 degrees btdc for cold starting/running, before reverting to 0 degrees btdc when the engine had warmed up a bit (@ c. 12 -18 degrees C.) Idk if this applies to your car.

Maybe try setting the ignition timing to 10 deg. btdc using a timing lamp, remembering that the 850 engine turns anti-clockwise unlike most other engines and see how it performs? Might be no harm to then check what the timing figure is at idle after the engine has warmed up, just in case your car is fitted with the oddball system described above. This is what I've done here to a few cars imported from the US. As long as you don't have any 'pinking' from the engine, it should be fine. YMMV....

P.S. Iirc, some of these ignition modules have to be bedded on a special dielectric grease (to conduct heat?), otherwise they will overheat.

Al.
 
Last edited:
Hi Al

Thanks for your comprehensive reply. The issue I am having is that the module appears to be failing when hot Apparently this is a common failure mode.

I would like to buy a new module. Any suggestions of suppliers would be welcome. There are lots online which have the same form factor but it seems that they are not all the same inside.

I would also be interested in any links to 466 testing that you have found.

thanks
John
 
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