Disable built-in rev limiter?

[John S]

I have a Pro Billet Ready-To-Run Distributor for Pontiac with built-in rev limiter. I'm also installing an MSD Digital 6AL box. The 6AL instructions include a note that state to set the Ready-To-Run rev limiter to zero. The Ready-To-Run instructions do not state how to set the built-in rev limiter to zero. Any help would be greatly appreciated. Thanks.

[Danny Cabral]

http://documents.msdperformance.com/...r_addendum.pdf (MSD Ready-To-Run Rev Limiter Addendum)

If you're using an MSD Digital 6AL CD ignition box with EFI, ensure the Rev Limiter Verification feature is disabled:
http://documents.msdperformance.com/6425.pdf (MSD Digital 6AL Instructions - Read Center of Page 5!)

REV LIMITER VERIFICATION The MSD Digital 6AL has an optional built-in Rev Limiter Verification feature. When the key is in the On position (not cranking or running), an RPM signal is sent to the tachometer to verify the unit's rev limit setting. With this function users can be sure of their rev limit settings before each drive. This feature is not activated from the factory. To enable this feature, follow the procedure below. Note: It is important to note that this feature should NOT be used with EFI systems. When activated, an RPM signal is sent to the tachometer. With an aftermarket EFI system, this will activate the injectors causing a flooding situation. Enable Rev Limit Verification 1. With the ignition switch in the off position, ground the Gray tach output wire. 2. With the Gray wire connected to ground, turn on power to the ignition without starting the engine. 3. Hold the Gray tach output wire to ground for seven seconds. (AT LEAST five seconds.) 4. Release the wire from ground before ten seconds have passed. 5. To confirm the process has worked, cycle turn the key On. The tachometer should sweep to the RPM limit set on the ignition. As soon as this process is complete the feature will be activated. The Digital 6AL uses the red LED to help indicate when an adequate amount of time has passed to release the Gray tach wire. The LED will turn on after the wire has been grounded for five seconds and will turn off at the 10 second mark. To deactivate the feature again, repeat the same process.

[Gaz64]

From Page 7:
ENABLE REV LIMIT VERIFICATION
1. With the ignition switch in the off position, ground the Gray tach output wire.
2. With the Gray wire connected to ground, turn the ignition on without starting the engine.
3. Hold the Gray tach output wire to ground for seven seconds. (AT LEAST five seconds.)
4. Release the wire from ground before ten seconds have passed.
5. To confirm the process has worked, cycle turn the key On. The tachometer should sweep to the rpm limit
set on the ignition.
To deactivate the verification feature, repeat the process.

So to disable the rev limit verification, follow the above.

[John S]

Thank you for the responses, but enabling & disabling the Rev Limiter Verification feature is not what I’m looking to do. I need to find out how to set the built-in rev limiter in the Ready-To-Run distributor to zero, so only the rev limiter in the 6AL box is active. I do not plan on using the Rev Limiter Verification feature.

I’d post a photo, but it appears that this forum doesn’t allow it. The note about setting the Ready-To-Run distributor rev limiter to ZERO when using a 6AL box with it, is on page 11 in this manual: https://documents.holley.com/6425.pdf

[Gaz64]

So you could just leave the distributor at the the default of 10000 RPM, or set it higher than your CD limiter:
PROGRAMMING THE REV LIMIT
A tachometer is required to set the rev limit. The limit is programmed by running the engine at half the desired RPM, then momentarily grounding
the Gray tach output wire from the MSD. A Gray jumper wire is supplied to connect to the tach with another tee-splice coming off to use for programming. A switch may also be installed to ease adjustments of the limiter (Figure 16). The default RPM limit is 10,000 RPM and the limit
is adjustable from 2,000 - over 10,000 RPM.
1. Start the engine and bring the rpm to half the desired rev limit (for a 6,000 RPM limit, raise and hold the rpm to 3,000).
2. While holding the RPM steady, short the Gray tach wire to ground
for approximately one second. Note that the tach will go to zero
while grounded.
3. The tach will now display the programmed rev limit amount for two seconds. If this value does not register on the tach, repeat the procedure and try a different ground source.
4. To confirm the rev limit value, turn the ignition key to the On position (without cranking the engine). The rev limit value will be displayed for two seconds on the tachometer.
Note: This RPM confirmation only displays when the Gray wire is being used to trigger the tachometer.