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Martin Cutler
Frequent User
Username: martin_cutler

Post Number: 92
Registered: 7-2007
Posted on Wednesday, 19 November, 2008 - 20:42:   Edit PostDelete PostView Post/Check IP

Hi guys,

Does anyone know the ohm rating of the ballast resistor for a T1? It has a Lucas part number on it, but no rating. I am guessing at about 1.5 ohms?

Cheers

Marty
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David Gore
Moderator
Username: david_gore

Post Number: 852
Registered: 4-2003
Posted on Thursday, 20 November, 2008 - 09:05:   Edit PostDelete PostView Post/Check IP

Martin,

I also think 1.5 ohms would be about right - a standard coil for a 12V electrical system was usually designed to operate at 9 volts to compensate for the voltage drop when starting and the ballast resistor reduced the voltage at the coil to this figure when the engine was running.

I would try and find/fabricate a wire-wound resistor with a rating of at least 50 watts and preferably higher. It also helps if you can relocate the ballst resistor from the bulkhead to the front of the vehicle to keep it cool - they are prone to overheating in the original bulkhead location.
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Colin Silver
New User
Username: colsilver

Post Number: 6
Registered: 8-2008
Posted on Thursday, 20 November, 2008 - 15:35:   Edit PostDelete PostView Post/Check IP

This link seems to confirm 1.5 ohms.
http://au.rrforums.net/forum/messages/17/3480.html#
A good read too by Patrick Lockyer, Et al.
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Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 1525
Registered: 4-2003
Posted on Friday, 21 November, 2008 - 01:54:   Edit PostDelete PostView Post/Check IP

Go for a Lucas 3BR or equivalent from Bosch, Delco or the like as it is the correct one. As the name implies, it is BR for ballast resistor. It is a 30W unit with a suitable mounting bracket included. It is 1.3 Ohm, designed to drop the coil voltage to 9V statically. Anythiomg from 1.2 Ohm to 1.5 Ohm will do. Replacements of all brands are compatible and available at any autoelectrician if you don't want a genuine part for some odd reason. Be prepared to pay as much as $10. Other brands are Echlin ICR11, ICR23, ICR34, Accel Part 150250 and so on. They are usually in ceramic housings.

If you must use an industrial equivalent, be sure only to use a hollow-cored epoxy-dipped 1.47 Ohm 50W one to save a few bucks.

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Martin Cutler
Frequent User
Username: martin_cutler

Post Number: 93
Registered: 7-2007
Posted on Sunday, 23 November, 2008 - 11:12:   Edit PostDelete PostView Post/Check IP

Thanks guys. The car is running smoothly again.
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Colin Silver
New User
Username: colsilver

Post Number: 7
Registered: 8-2008
Posted on Sunday, 23 November, 2008 - 20:00:   Edit PostDelete PostView Post/Check IP

Just what we like to hear.
Well done.