6500 Rev Limiting Rotor does not limit...

Hi all-

Replaced my ignition rotor on my last tune up and I noticed it does not limit at 6500RPM as it should. Part number 911-602-928-00-M14. So, I swapped it out with an identical one. Same issue, both purchased from Pelican. This is for a stock '72 T with MFI.

I revved the car to about 6700-6800 and there was definitely no limiting going on. Both rotors are mechanically limited and the springs moved freely.

Has this happened to anyone else? Maybe Bosch has put out a bad batch... AutoX season is quickly approaching and I really count on that thing working!

Thanks,

Jorge

Not sure what to suggest other than to replace with a solid rotor and use an aftermarket ignition box with built-in RPM-limit circuitry (i.e. Crane, MSD, etc.). OTOH, keep the existing rotor. You already have an equivalent "solid" rotor.

Sherwood

The cutout speed is marked on the rotor, is it marked as 6500?

How are you testing this are you just reving the motor to 6500RPM I would suggest hooking a timing light to one of the plug wires and rev it up and see if the light goes out...just a suggestion one other thing most of the Bosch stuff offered today is seconds that most parts suppliers get cheaper and sell for more...

Thanks Sherwood, I've been thinking about going that route if I can't get a rotor to work. I suppose I could put the old one back in, but it's pretty beat up.

Ed, yes, both rotors were marked 6500. They were Bosch parts, made in Spain. I flipped both over and made sure the spring moved freely. Strange, isn't it?

How do you know you're revving to 6500?? Old Porsche Tachs (particularly when driven off of a stock distributor) aren't too accurate. This was exactly how I discovered that mine was off about 300/400 revs.

Pertronix make a good, adjustable, solid state rev limiter for your application. But remember that rev limiters come with a mechanical price too. They're hard on our old cranks.

johnt

Not totally sure but I have read that the rev limiting rotor will only function properly under load ( while driving ) they won't save you from a missed shift, so static test won't indicate function or not. Baloney? Bologna?

David

I think that you are confused. You dont need a load, teh rev limiting rotor works on centrifugal force, so load is irrelevant. However, no rev limiter can prevent a mechanical overrev, such as when you shift from third to second instead of fourth at 7000 RPM! :eek:

You can alter the rpm cutoff by bending the tab that holds the spring.

JohnT, my only point of reference is that the old rotor limited me at 6500. The style is different than the replacement, but I imagine it should work the same. All three had 6500 printed on them.

I did test under load, while driving, fwiw. I was careful not to enter 7000 territory, which I don't think would be a good idea on the T.

Has anyone recently replaced their rev-limiting rotor with onethat actually works?