angelfj Posted March 5, 2009 Report Share Posted March 5, 2009 I am trying to establish what would be the correct ignition coil that was fitted to my 3A. The Lucas catalog (No. 725 Fast Movers) lists part number 45212 for the GT6, TR3, 4, 4A and 5 ignition coil. This doesn't seem correct since the early cars utilised a screw type HV connection whilst the later cars had the modern push on connection. Any Lucas experts out there who might shed some light on this question? Thanks in advance. Quote Link to post Share on other sites
Don Elliott Posted March 5, 2009 Report Share Posted March 5, 2009 My reference is page 6 of the 1958 Lucas parts catalog for "Standard & Triumph Cars". It shows the coil as 45053J (model LA12) and 45054J (model HA12). I cannot find out why there ore two types or what the differences are. My original coil is like this one shown. It is still on my 1958 TR3A with the two small studs straight up out the top and two small brass hex nuts to secure the wires. Quote Link to post Share on other sites
angelfj Posted March 5, 2009 Author Report Share Posted March 5, 2009 My reference is page 6 of the 1958 Lucas parts catalog for "Standard & Triumph Cars". It shows the coil as 45053J (model LA12) and 45054J (model HA12). I cannot find out why there ore two types or what the differences are. My original coil is like this one shown. It is still on my 1958 TR3A with the two small studs straight up out the top and two small brass hex nuts to secure the wires. Hello Don. Trust you are well and thank you for the reply. Can you tell me, is there a part number stamped on the aluminium case, perhaps on the bottom? yes, I have several photos of your engine bay, so I know that what you have is the real thing. But, the catalog listing is puzzling. Cheers, Frank Quote Link to post Share on other sites
ianc Posted March 5, 2009 Report Share Posted March 5, 2009 Not only did early cars have screw terminals on the coil, but they were positive earth (but some cars - like mine - have been converted to negative earth because an alternator has been fitted in place of the dynamo). TR4A onward were negative earth. In order that the spark may jump across the plug gap as intended (spark jumping from centre electrode of plug to the outside), a different coil is required for positive and negative earth cars. With the wrong coil/earthing arrangement, the engine may run, but not as well as it ought. Ian Cornish Quote Link to post Share on other sites
Don Elliott Posted March 5, 2009 Report Share Posted March 5, 2009 Frank - Here is a photo of the bottom of my coil. It was taken in 1987 when I started my restoration. It still works fine. Quote Link to post Share on other sites
angelfj Posted March 5, 2009 Author Report Share Posted March 5, 2009 Frank - Here is a photo of the bottom of my coil. It was taken in 1987 when I started my restoration. It still works fine. REMARKABLE! Thank you, Frank Quote Link to post Share on other sites
scuttleshake Posted March 6, 2009 Report Share Posted March 6, 2009 The Lucas model number prefixes translate to something like this; HA - high performance LA - standard BA - older coding for coil used with a ballast resistor (later 16C?) SA - sports The suffix indicates the volltage 6 or 12. Regards Marke Quote Link to post Share on other sites
Alec Pringle Posted March 6, 2009 Report Share Posted March 6, 2009 Hi Frank, Martin Jay must have just about every Lucas ignition reference book ever produced - he's bound to be able to come up with the definitive answer . . . . If you email him and ask nicely, he'll probably be able to give us the lowdown on the whole TR range ! Cheers, Alec Quote Link to post Share on other sites
angelfj Posted March 7, 2009 Author Report Share Posted March 7, 2009 Hi Frank, Martin Jay must have just about every Lucas ignition reference book ever produced - he's bound to be able to come up with the definitive answer . . . . If you email him and ask nicely, he'll probably be able to give us the lowdown on the whole TR range ! Cheers, Alec Alec: That's a good idea. I'll send him an email. Quote Link to post Share on other sites
ianc Posted March 9, 2009 Report Share Posted March 9, 2009 Following my earlier posting about earthing and coils, I received an e-mail from Pete R-C as follows: Hi Ian, Sorry to trouble you but I am concerned about a comment you made in a recent post about ignition coils. You said "a different coil is required for positive and negative earth cars. With the wrong coil/earthing arrangement, the engine may run, but not as well as it ought." Having searched Moss & Revington websites they seem to be selling the same coil for TR2 - TR4A. I have changed my 3A to negative earth, reversing the coil contacts, and am worried that I have the wrong coil. Can you clarify this point please. Regards Pete R - C In case others are similarly perplexed, I am posting my reply here for all to see. Dear Pete, If you have a standard TR2/3/4 coil, it will have terminals marked SW and CB, the latter being the connection to the contact breaker in the distributor. Modern coils are marked plus and minus (+ and -); I have just checked this on the coils fitted to my car in 1992. So, regardless of which battery connection is earthed, it is obvious with a modern coil which way round the coil must be connected - for example, if you have negative earth, the - connection goes to the contact breaker and the + to the ignition switch; if you have kept to the original TR2/3/4 (positive) earthing arrangement, the + connection goes to the contact breaker and the - to the ignition switch. In reversing the connections to your coil, you now will have the coil's SW terminal connected to the contact breaker and the CB terminal connected to your ignition switch, and in so doing, you will have overcome the problem which I described. Thanks for raising this - I hope this answers your question. Ian Cornish Quote Link to post Share on other sites
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