hi. went and got myself a pulsar dizzy at Pick 'n Paymore on friday. it came with a Bosch GT40 RT coil. is it better or worse than the GT40 R???

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http://www.minisport.com.au
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Put a meter on it and check primary resistance (the 2 small terminals).
Should be 1.5 ohm. I think RT is.. (R means it's 1.5 ohm, T means transformer case) but check anyway.

Rumour has it these `transformer' epoxy filled ones can fail due to cracking, but I ran one for years with no problems.

Alternative is the old GT40R (oil filled one) still available, and cheaper.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The epoxy filled units are deffinately much more resistant to moisture in my experience.
I never had a problem with wet weather driving when I had the GT40T coil. The oil filled resistor coil that came with the Pulsar dizzy used to be ok in wet weather too untill recently, but for the last week driving in any sort of wet conditions became impossible with missfiring and stalling all the way. WD40 on the coil would fix it all but then the moisture would get to it again within minutes.

I reckon this is due to replacing the UK MK2 (hexagonal) grille for the Australian moustache type grille. The UK unit has a chrome lip that attaches to the bonnet lip and effectively deflects water away from the gap between the bonnet and the grille. The Aust. one has the slit, under the bonnet lip, open and water can travel straight onto the coil. A pink rubber glove tight on the coil and on the coil lead that goes through one one of the rubber fingers solved the problem quite well. I've got an epoxy filled resistor unit that I want to try to see if I can get away without the glove. (Or might do the doc mod with relocating the coil).
Otherwise gonna have to sorce some BMC Engine Green oil resistant rubber gloves.

BTW I havent been able to find an epoxy filled coil with a resistance above 1.3ohm. And Bosch do not list a coil unit for the N12 Pulsar, nor do they provide any assistance for it. I tried calling them but they said they do not recomend using their products on the N12 or with its distributor.

Bosch GT40-T is 3 ohm (I have one here),
GT40-RT is ~1.5 ohm,
there is also another one (forget code) that is 1.1 ohm (made for other electronic ignition systems) but I wouldn't use it on the Pulsar dizzy.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Huh? Moisture INSIDE your coil?? I thought a coil was sealed...?

As a coil gets older, do the ohms drop?

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Website: www.justanothermini.com

Not inside your coil but right on top of it where the low tension terminals are and the high tension output to the dizzy is too. I understand that water there causes spark crossover, shorting out the coil.

And wouldnt the resistance rise as the coil gets older?

Resistance of a coil should not change with age, the length of the wires inside is the same...
What happens is, often old coils have micro cracks in the plastic top. Just add water and U get spark flashover problems.

At least with these new `transformer' shape Bosch coils, the H/T is at one end and the primary terminals the other, so this is less likely to occur.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.