Ignition coil for 250 se / 280se

[cliffk]

Hi can anyone tell me what type of coil I should have, I am rebuilding previously dismantled car from boxes but there is no coil, I have a ballast resitor? on the inner wing (fender) below the coil position which gives me a reading of 9 volts or thereabouts (12 volts in 9 volts out).
I have been told these cars operate the coil on 9 volts so my questions are:-
1. Should the coil be a 9 volt one instead of the regular 12 volt
2. Can a 12 volt coil be fitted? if so under the present wire arrangment it will only get 9 volt to the + side
3. Can a 12 volt coil be fitted and the 12 volt feed to the ballast resistor go straight to the coil bypassing the ballast resistor.

The reason the title is 250se / 280se is because my car is a 1966 250se coupe fitted with a later 280se motor.

Any advice appreciated

[Jub]

Wow CliffK,

A 250 fitted with a 280 engine (always wondered if that were possible).

Cool

[Palolo]

1: No. Your coil momentarily sees 12v during starting, then sees 9v during running, as intended, in an attempt to preserve the points.
2: Yes, but do fit the right type
3: Yes, but... The resistor is there to prevent the points from burning out during operation. If you no longer run points, then the ignition system will have coil recommendations, and you can bypass the resistors. (fwiw, my distributor does not contain points, so I bypassed my resistors, and run the hotter "red coil" as recommended by the ignition/distributor manufacturer*)

The 113s have essentially the same systems, and their owners have a great resource that should spark some ideas...

See the diagrams on these pages for explanation of what the resistor/s do:
Pagoda SL Group Technical Manual :: Electrical / TransistorIgnition

Pagoda SL Group Technical Manual :: Electrical / IgnitionSystem

Coil info: Pagoda SL Group Technical Manual :: Electrical / IgnitionCoil

*side note; Look in to ignitions from Pertronix, Crane or that which my car uses: "a modern Dutch distributor that controls advance, whose name invites inevitable sniping about cost, but supposedly is as easy to install as 1-2-3!"

[cliffk]

Jub
Its not that difficult its basically the same engine but on mine there are several parts which are 250se parts fitted to the 280se engine the oil filter housing and cooler tank for instance.

Pal.olo thanks for the advice and links