Distributor
The original Lucas 23D4 distributor has finally given up after 40 years of abuse and has cracked 180o around the base. As the bodies for the 23D4 are no longer available, the question is what to replace it with? There are a number of options: full ignition map with an ECU, Lucas 45D4 mechanical distributor or a fully electronic distributor.
As the engine in my Lotus is modified some what after a few years of tweeking, being able to easily modify the advance curve is a feature I would like to have. This eleiminates the mechanical 45D4. Next to be eleimiated is the ECU primarily on grounds of cost. The ECU is quite expensive then you have to add on the associated sensors, wiring and rolling rode time to create the ignition map. While I am no purist when it comes to originality I think that an ECU is a step too far.
I am now left with the fully electronic distributor and this is what I have decided to go with. 123 ignition make a very high quality product, the body is machined from solid steel, so it should not suffer the cracking of the original units. The devices comes with 16 preprogrammed advance curves, easily seletced via a small switch. There is a specific version for the Ford based engines in development but before that is released pioneers can use their GB-4-R-V model. This comes with a dog drive that will need to be swapped out of the gear drive of the Ford type.
New Ford type drive gear for Bosch type distributor now purchased. I initially thought that I would be able to fit the new drive gear to the existing distributor shaft, however the shaft is really too short. Additionally because the Ford type drive is helical some of the drive force will tend to pull the shaft down through the distributor, the current design does not allow for this as there is not a thrust washer to take the load. A new longer shaft is now being made and will include a thrust washer.
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| 123 Distributor |
Longer shaft and Ford drive gear now fitted along with right angled cap (Bosch 1 235 522 332). I just need to find a set of leads now.
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| 123 Lotus/Ford Twinc |
New leads arrived from Magnecore. All fitted to the engine now and fired up first time. Checked the timing with a strobe and it is much more accurate than the old mechanical system with zero scatter, the tick over is better too. I am starting with curve setting 7 as this is closest to standard for the Stromberg engine.
Finally completed some road testing and all went well. Tried the next curve up setting B, no pinking and slight better at high rpm. The engine appears more free to rev and is smoother, this is propably down to zero scatter on the timing. I am making much more use of the rev limiter now.
I used this spreadsheet to compare curves.
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| Dizzy in place |