Lotus Elan

Rotor arm and rev limiter .... what now?

PostPost by: Bruce Crowthorne » Fri Oct 14, 2016 2:29 pm

My car had an annoying misfire. Fine when first started, fine until hot, leave it standing for a few minutes, then it mis fired! Also mis fired after being stuck in a queue. What a pain. Seemed to be heat related. Started with plug leads, then coil and it turned out to be the rotor arm.

In my quest for originality I kept the original (probably from 1968!) rev limiting rotor arm.
Really can't complain that it has finally failed after 48 years!

However, I no longer have a rev limiter. The car has an Aldon Igniter electronic ignition tucked inside the distributor (so it doesn't show), and I guess I have three choices ...

1) Do nothing, after all it's old and gently driven and I d't think I have ever revved it to 6,500 rpm anyway
2) Are the rev limiting rotor arms still available? Must admit I haven't done a search ....
3) Add some form of electronic rev limiter. Probably Aldon will do one, if not the swap to an ignition supplier who does

What are the opinions and what does everyone else do?
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PostPost by: richardcox_lotus » Fri Oct 14, 2016 3:02 pm

Option 1 for me. 4K revs in 4th is between 70-80 mph in my sprint, so I rarely get up above 5k revs.
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PostPost by: billwill » Fri Oct 14, 2016 4:26 pm

The rev-limiting rotors become available on eBay from time to time. I think in Land-rover parts nominally.

The one you need is rated 3250 RPM (the distie speed)

SEarch this site and you should find messages about them.
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PostPost by: john.p.clegg » Fri Oct 14, 2016 4:27 pm

richardcox_lotus wrote:Option 1 for me. 4K revs in 4th is between 70-80 mph in my sprint, so I rarely get up above 5k revs.


I take it you've never had the throttle stick open....

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PostPost by: richardcox_lotus » Fri Oct 14, 2016 9:06 pm

Nope.

Or at least, not yet.
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PostPost by: saildrive2001 » Thu Oct 20, 2016 12:00 am

I have a Petronix electronic rev limiter on my car with their ignition system.
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PostPost by: billwill » Thu Oct 20, 2016 6:52 pm

Some discussion of these rotor arms her:

lotus-electrical-f38/rev-limiter-t20756.html

But there is another topic somewhere where many of us bought such arms from eBay.
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PostPost by: Bruce Crowthorne » Tue Oct 25, 2016 2:29 pm

Thanks Bill, I hadn't found that thread.
It mentions that QED had rev limiting rotor arms (in 2010...) but when I checked their web site it looks like they no longer do them.
Pity.
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PostPost by: Orsom Weels » Tue Oct 25, 2016 3:53 pm

I'm with Richard & option 1, & I have had the throttle return spring jump off & jam the the linkage at near wide open :shock: I did have a rev limiting rotor at the time, but on British roads, with 6500rpm equating to around 120 mph it didn't really help much, I had already switched the ignition off long before we reached anywhere near that sort of speed :wink:
Neither of my cars have the rev limiter rotor arms now, they got changed when I converted to pointless ignition, the kits came with nice new & recommended red std rotor arms.
Even if you do take it to those kind of rpm's, I genuinely think that a momentary over rev could potentially do less harm than the sudden loss of power, followed by the sudden return that you get when the limiter kicks in & out, that must put all sorts of stresses through an engine, not to mention your rotoflexes, if you still have them. Just my humble opinion :)
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