Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: SteelCityLotus on Wednesday,June 09, 2021, 10:15:11 AM
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Hello everyone. I haven't been posting very often because I've found nearly everything I've needed by using the search function. I've been taking lots of pictures and I need to find time for a big post documenting my progress on 4163R.
On to today's issue!
I've awakened the Twin Cam after a long slumber and am now working through smaller things, like timing adjustment. I bought a used Pertronix Ignitor II distributor on Ebay and didn't have any issues dialing in initial timing. I also bought a new matching coil to round out the system. When it came time to check advance, timing stayed the same as I revved the engine.
Upon pulling the distributor apart, I found that is was modified to pin the timing weights as shown in picture 1. I had already pressed out the roll pins when the picture was taken, so they're sitting above flush in the holes for reference.
I also found a set screw that locks the upper and lower module plates together as shown in pictures 2 and 3. It passes through the lower plate and threads, poorly, into the upper plate. I'm not sure if that screw is standard, but it seemed like another modification.
I've ordered advance springs to replace the ones removed during this modification, but I was wondering if anyone had a picture of how the mechanical advance mechanism fits together. I have a pretty good idea, but I want to make sure I'm not missing any additional components. I put in a help ticket with Pertronix, but I don't know how willing they are to share exploded diagrams as I have yet to find one anywhere on the internet.
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Hopefully this helps......
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??? ????
All I can think of it that it must have been used with a digital advance system.
The Lotus Twin Cam have very specific advance requirements. Don't just plug in any old springs.
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??? ????
All I can think of it that it must have been used with a digital advance system.
The Lotus Twin Cam have very specific advance requirements. Don't just plug in any old springs.
Absolutely agree. I could only find one set of springs that Pertronix sells for all distributors. If they keep the weights constant, I'm thinking they can use the same springs for all distributors. The springs are rated by the RPM at which full advance is reached. I believe this is how the distributor was designed, so we'll see how it works in practice when the springs arrive tomorrow.
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Hopefully this helps......
That seems to line up with what I thought it should look like. I'll give that same configuration a try for my initial run.
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I may be misremembering, but didn't the stock twincam distributor have a vacuum retard? At least the Fed version? My Pertronix dizzy has no vacuum port and I seem to remember a slight advance with revs.
Tom
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Only the Federal version of the Lotus TC engine had a vacuum ignition control. You right, it retarded the ignition, not a desirable option.
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The pic I posted shows a crusty retard canister.....that is disconnected.
I bought another distribuor as this one is quite crusty.
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I wanted to post my resolution to this issue because it may help someone in the future.
I ended up buying the advance spring kit from Pertronix and fitting the combination that had the closest advance curve. That didn't work out as the distributor over-advanced by a considerable margin. The advance limiters provided with the spring kit didn't help either.
I ended up swapping the shaft and advance mechanism from the stock distributor into the pertronix distributor housing. The stock advance mechanism sat too low in the pertronix housing, so I shimmied it up with a thin washer for clearance. That made the rotor sit higher and interfere with the cap. I ground down the bottom of the rotor until everything fit nicely and the cap secured without issue.
Everything is running fine now!
Not quite the way I saw this going, but that's what you get with used Ebay parts.