Generator Control Box Lucas RB340

[SpitfireGeorge]

Hi Guys,

I have the above fitted as standard to my '67 Spitfire Mk3. There are plenty available new on Ebay for considerably less than the usual parts suppliers. Most say for Ford though. Will they fit or are they set up differently and need adjusting?

Cheers,

George

 

[Pete Lewis]

as far as im aware the lucas RB340  was a fixed specification matched to the C40 or C40L  dynamo 

all std fit on many uk cars of the era 

one thing is clear dont mess with any its easy to create a disaster how ever careful your DIY skills are

way back  we had to test them under warranty on trucks and that was a un enviable  task 

thank heavens alternators were developed 

Pete

[SpitfireGeorge]

Thanks Pete.

[Mad4classics]

As Pete says, you need to know what you're doing before you fiddle with a control box.

There are actually many variants of the RB340 with different current settings for a specifically associated dynamo each with a unique Lucas part number - it doesn't matter if it comes from a ford or wherever.

C40 needs a control box set to 22A and C40L one set to 25A.

Care needed because the different five digit lucas numbers give a range from 10A to 35A all being RB340 based.

David

 

lucas RB340 Part Numbers.pdf

[SpitfireGeorge]

Hi David,

Thanks for the info. According to my Haynes manual I have a C40-1 fitted which is not on the list. Where is the part number on the RB340?

Cheers,

George

[Mad4classics]

Hi George,

A C40/1 is a 22A dynamo.

The control box number should hopefully be stamped onto the baseplate, usually on the back.

David