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Electronic Ignition  Rating:  Rating
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 Posted: 03-26-2014 07:37 pm
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Chiefaes
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I recently acquired the above 73. It has an electronic ignition module "Crane XR700". I need to know what I need to add to make the Tach work? I was told by the previous owner that I needed some component to make it work. Would it be easier to replace that model?

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 Posted: 03-27-2014 02:04 am
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Art DeKneef
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The insides of the tach need to be rebuilt with components that work with an electronic ignition or buy a new electronic tach.

The JH ignition circuit goes through the tach to start the car. So make sure all the wires are accounted for if you switch.

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 Posted: 03-27-2014 06:10 am
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subwoofer
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Use a Pertronix-II instead. Works with my tach (to the extent said tach can be said to be working, it is old and knackered), installs in the same amount of time you use to change points. Not horribly expensive either, $130-ish.

--
Joachim

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 Posted: 03-27-2014 12:59 pm
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Brett Gibson JH5 20497
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I run the Crane XR700 with no mod's to the tach and it works ???

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 Posted: 03-27-2014 02:49 pm
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Chiefaes
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Are there any wiring differences to be considered. Can you send me a schematic for the wires from ignition through the Tac?

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 Posted: 03-28-2014 02:16 am
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Art DeKneef
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For a good breakdown of all the electrical circuits download Jim document here: http://www.mediafire.com/download/1hf6sg1350m9f5n/Kimbrough+wiring.pdf

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 Posted: 03-28-2014 05:07 am
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Tom Bradley
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I also have also had an XR700 for many years. The tach works OK, but reads about 30% high (checked against a couple of reliable references). There is a trimmer on the back of the tach (hidden underneath some electrical tape on mine), but it is hard to get to, so I have not taken the time to try to adjust it.

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 Posted: 04-01-2014 04:06 am
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Jensen Healey
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I had trouble with the XR700 hitting the inside of the distributor cap and opted for the Pertronix. There's no need for the huge heat sink with modern electronics.

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 Posted: 04-20-2015 07:12 am
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Schorse
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Getting back to a distributer question. With my spare engine I bought a Lucas 45DM4 electronic distributer. Which came from an Esprit. Will this also work with my tach on the standard engine?

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 Posted: 04-20-2015 12:10 pm
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NigelK
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Hi Georg

Mike Taylor at LotusBits is also fitting the same distributor to the engine of my GT, which is currently being upgraded to 907/912 hybrid spec. The Lucas 45DM4 distributor included an optical trigger in the cap and in later Lotus Excel / Esprit incarnations was used with an external ignition amplifier called the Lucas AB14.

Together, these components comprise essentially the same circuitry as is found in more modern Pertronix and Accuspark units, which in more recent years has been manufactured small enough for the entire thing to fit inside the distributor cap.

General consensus would most likely be that you're better off installing a more modern unit, however I'm not sure either Accuspark or Pertronix make a points replacement unit for the 45DM4 distributor.

As for tachometer function with the 45DM4 / AB14 combination, Mike says it has worked fine with the RVI tachometer on other Jensen Healeys he has worked on. I'll let you know whether I have any problems with my GT, probably later next week.

Best wishes,
Nigel

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 Posted: 04-20-2015 08:41 pm
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Schorse
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Thanks Nigel,

you must be very excited starting your engine up for the first time. That is basically what I had in mind but then I didecided to do the impossible and fit a 912HC. This project will have to wait till I'm moved in.

Hope your engine turns out how you hoped it would be like.

Georg

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 Posted: 04-20-2015 08:43 pm
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Schorse
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One more thing, is the amplifier fit to the engine? Because I didn't see it so far...

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 Posted: 04-20-2015 09:49 pm
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NigelK
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Hi Georg

From what I've read on the JHPS and JOC fora, it's easier (read, less difficult) to fit a 912 engine in a LHD GT than a RHD GT.

Mike Taylor reckons the 907 bottom end is fine to use with a 912 cylinder head. Even though the 907 bottom end is less rigid, this does not really matter except in 200bhp plus applications. I should have around 180bhp so I'm comfortable...

The AB14 is literally a black box, usually mounted on the engine bulkhead or the inner wing, close to the coil. I do not think it should be mounted on the engine itself.

Google images "Lucas AB14 ignition amplifier" and you can see some pictures of what it looks like.

Best wishes,
Nigel

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 Posted: 07-18-2015 05:35 pm
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NigelK
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Hi Georg

My GT is now running, and I went up to LotusBits earlier today to finalise various outstanding jobs. They have fitted the Lucas 45DM4 distributor and AB14 ignition amplifier from the Lotus Excel. The AB14 is mounted on the engine bulkhead, using the mounting points used for the engine damper on the Jensen-Healey. Unfortunately the original Smiths RVI tachometer does not work, and Mike has fitted a voltage triggered VDO tachometer from a Lotus Excel and rewired the circuitry behind the dash and at the coil so it works. I have just sent the Smiths tacho to Spiyda Design for conversion to RVC operation, so it should work with the AB14.

Next week the car gets MOT'd and the week after it'll be on the rolling road. Based on a quick run up and down the drive to Mike's workshop, there is a lot more torque and therefore no issues whatsoever with the Toyota W58 gearbox and the original 3.45:1 cwp rear end.

Of course more shaking down is required, particularly after such major works have been completed, but the early signs are very good indeed.

Best wishes,
Nigel

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