7500 Rev Limiter for Bosch 6 pin

[Gib Bosworth]

Does anybody have a suggestion for a rev limiting device that can work with a 6 pin Bosch CD? As far as I can tell, all the aftermarket offerings are for Inductive ignition units and will not work with the capacitive discharge Bosch unit. Has anyone modified a stock speed switch used on the SCs to a higher RPM limit? Does anyone have the circuit diagram for the factory speed switch...as it could possibly be modified with a resistor change to a higher rpm limit?

Gib

[fred cook]

The easy way out will be to install an MSD 6AL box or equivalent. It has an adjustable rev limiter built in. Cost is reasonable also. You can use male crimp
on plugs and simply plug it into the stock master plug. Easy install!

[Gib Bosworth]

Yes, Fred, I know MSD is a solution, but I am building a period recreation and don't want to use MSD. There are a number of other similar rev limiting products out there for Inductive Ignition systems, but still looking for a solution for CD ignitions.

Gib

[aturboman]

Gib I sent you a PM

[Gib Bosworth]

I am still looking for an after market Rev Limiter for a Bosch 6 pin CD ignition system. The factory speed switch relay for the SC and Turbo had limits of 6700-6800 I think, and I wonder if one could be modified to get a 7500 limit? Does anyone have any knowledge of the the circuitry inside the factory speed limiter relay?

[john walker's workshop]

78/79 930 used a 7000rpm distributor rotor. you need a large body SC distributor to use it.

[Gib Bosworth]

I have a twin plug engine with a JB Racing dizzy with Bosch CDIs and need an external Rev Limit unit. I think Crane used to make one that would work with a CDI (NLA I think), but most available today are for MSD or Inductive units. My thought was that one of the later SC rev limiting relays could be reworked to recalibrate it to 7500 or so.

[Flat6pac]

I was always under the impression that the limits were set inside the tach on the SC cars
Bruce

[Gib Bosworth]

After 79, they used a relay which mounted behind the instruments on the left side. It shut off the fuel pump when the rev limit was reached, and later it cut off the CD power I think. I would use the relay output to cut the power to the CDI units, but I need a way to take the tach signal and sense when it reaches 7500 or so, which would then open a contact, dropping the 12v to the CDI units.

[john walker's workshop]

why do you really need one? keep an eye on the tach, don't mechanically over-rev and you're fine. nothing like hitting the windshield when it cuts out at 7500. an engine like yours should take 8500 without giving up if it's built right.