Testing rev limiter

[spandit]

How does the rev limiter work and is there anything I can do to make sure it's working properly (i.e. actually turning the light on at 4500rpm)?

[stiffler4444]

Floor it and see...I lit mine up going up north last summer, doing just over 115kph........

[Fleg]

Does the 4500 light ever come on? I thought I read somewhere that it will light up during start up but mine doesn't. Mine has never illuminated.

[Jim LaGuardia]

It should flicker when key is turned on, if not replace the bulb.

[Jimm391730]

As best I can tell from looking at a dead rev limiter, the current that feeds the coil pulses through the limiter as the points or Pertonix connect to ground - the rev limiter detects this current and uses it to determine the RPM value. If the revs go too high, the rev limiter reduces the current to the coil to stop the spark, therefore limiting the engine revs. The lamp is supposed to be illuminated when this occurs.

The rpm module was designed/built in the 60's and 70's from discrete components (no ICs) and is subject to drift and failure; so even if it doesn't fail outright, it can easily change it's performance to higher or lower rpms. I my case the limiter was gradually reducing the power to the coil, without regard to the actual rpms until I had only 8 volts at the coil terminal (~18 volts is normal). As I am not worried about the likelyhood of over reving the engine I just bypassed the rpm module as the solution.