Pertronix Ignition
After the ignition failures on two previous outings I decided it was time to change to a different system. Just to make life more complicated the Lucas 44D4 distributor on the Sprint engines is unique with its low level side-entry cap to fit under the inlet manifold. It is possible to use a different cap & rotor that allows more types of ignition from the Lucas 45 distributors but I thought I would keep that option for a last resort.
Looking around at the alternatives some are very cheap and some are very expensive! I decided to go for something in the middle that was recommended by several folks who work on old cars for a living. I chose the Pertronix Ignitor and managed to buy the exact one I needed from Martin Jay who trades as The Distributor Doctor. He can also rebuild a distributor as good as new so is a useful contact as well.
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| Pertronix kit and contents |
The Pertronix uses a rotor containing magnets that fits over the distributor spindle and a sensor fixed to the baseplate. It has very simple wiring - only two wires - as you can see from the picture. Fitting it in the distributor would be easy but the Sprint engine is awkward because of the location and I was being extra carefull not to drop any of the little screws down inside.
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| Pertronix Fitted |
The red wire is the 12 volt ignition feed and the black one is the switched signal back to the coil. I needed to provide a 12 volt feed to the coil and to the Pertronix and from the previous post you may recall that we had also messed about with the ignition switch trying to get it going. I had a brand new switch but comparing with the old one I noticed that the multi-pin plug on the end was wired differently. These are being sold as the correct item under the Lucas part number but is obviously not correct for the TR7. Luckily this was easily swapped over but would have been a problem if I hadn't spotted it.
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| Spot the Problem! - Different Wiring |
I also wanted to add the additional 12 volt live ignition feed and an auxiliary feed to the new switch. The 12 volt goes to the Remax coil and Pertronix. The auxiliary feed goes to the dash cam and satnav.
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| Modified Ignition Switch Wiring |
I stripped off some insulation and soldered the extra wires on before adding some shrink down insulation over the top for protection. May not be professional but it is safe and secure.
After fitting the new switch and Pertronix the engine actually fired up. It was a bit lumpy because the ignition timing was out but this was easily corrected with my old Snap-On timing light and it was idling nicely afterwards. A quick road test and it all felt good so I am hoping that will be the end of ignition troubles.
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