Bosch Blue Coils

[Angus]

Any idea how I tell if the coil(s) I have need the external ballast resistor?

Thanks!

Angus

[Albatross]

Unlikely. Engine type ? Distributer type?

[Angus]

1600cc "Kent" engine
Bosch distributor with points.

[Steve Davis]

If the internal resistance of the coil is ~1 ohm or less, it does NOT have an internal resistor and therefore needs one externally. (from + to - , the 2 contacts that go to the battery and distributor.)

If it's above 4 or 5 ohms, then it does PROBABLY have an internal resistor.
Steve, FV80

[revtom]

I'v used the Bosch blue in a number of cars, including my FF, without any external resistor, just straight hook-up.

[Steve Demeter]

The Bosch blue coil has an internal ballast resistor in it.

One less external thing to go wrong.

And like most anything Bosch, they are dead reliable. Period.

[Angus]

Thanks for the input.

Both of my "blue" coils were in the 3.5 to 3.6 Ohm range. Don't know why i didn't think of checking this way earlier.

One of the coils I purchased from Pegasus as a spare, they state this one doesn't require a series resistor. The other came with the car. The resistor looks like it could have been their for decades.


Thank you.

Angus

[Steve O'Hara]

On the subject of Bosch coils, are they sensative to heat? If so, how much does it take to cause trouble?
Steve O'Hara

[Steve Davis]

Coils are not OVERLY sensitive to heat, but I wouldn't mount one to an exhaust header. Still it's best to keep it away from anything that generates lots of heat. I've seen tons mounted on the back of the firewall within inches of the engine heat, but I would suggest that you mount it as far away from the engine heat as you can get it - within the limitations of the length of the coil wire. NOT directly mounted to the engine in any way. I mounted mine to the frame rail just in front of the fire wall.

Steve, FV80

[Earley Motorsports]

I believe the rule of thumb is the coil lead should not be anymore than 12 inches.
Graham.