Older Mopar branded MSD 6al box - how to set rev limiter? ...and which distributor?

[Spyder]

I've got the old black Mopar branded MSD 6al box on my car. It's supposed to have rev limiter ability and I've seen reference to 3k, 5k, 6k, and 7k "buttons" to program it. The instructions and any spare parts or "buttons" are long lost 15 or more years ago, probably 20, and I'd like to set up a rev limiter on this car. What's the best plan for that, sell this thing and get a newer 6al box with the dials? I'd rather keep it since it looks great as is with the Mopar branding on it, but I'd rather protect the engine over that.

I'd also like to replace the MSD distributor with something that's got vacuum advance. I bought this MSD about the same time as the box, back when I knew even less than I do now. What do you experienced folks recommend for a street 440>512 distributor with vacuum advance?

 

[Spyder]

This one.

 

[pschlosser]

(guessing) inspect that big square area on the front, is it removable to expose some dials?

 

[Spyder]

Nope, that's what I thought too. Went out and pulled it off the fender and looked around it today, that's why it's crooked in the photo. There's a black plug that goes into the side of it towards the bottom of that photo that I think is probably the "button" mentioned in old literature. Some photos I found of this part number show several of those, so maybe they're little plug in things that are pre-programmed with the limit?

I saw some old instructions saying to rev the engine to half the RPM you want the thing set at and then ground a wire for between a half and 1.5 seconds and it will set itself there (ie., rev to 2500rpm to set the limiter at 5k) but I haven't found surefire confirmation or good directions yet.

It'll be one of many winter projects so I guess I don't have a big rush, but if I need to update to a modern box, I oughta put some cash aside each paycheck.

 

[Spyder]

Page 9 of the linked instructions below, line 36, says "To set rev limiter, insert the jumper with desired RPM number into the side of box. Included jumpers were 3000, 6000, 7000, and 8000." I think that's what I have. I'll have to go look at it tomorrow and see if the "jumper" on mine has any indication of which one it is. If it's the 6000, I'll just leave it there and call it good.

https://lib.americanmuscle.com/files/msd-ignitionmodule-revcontrol.pdf

This one is Analog, not digital, so I kind of want to keep it for that reason too. Anecdotally, I'm not seeing any analog boxes failing while lots of complaints of digital ones going bad. Plus, right now, it works. If it ain't broke, don't fix it!

 

[Vaanth]

I've got the old black Mopar branded MSD 6al box on my car. It's supposed to have rev limiter ability and I've seen reference to 3k, 5k, 6k, and 7k "buttons" to program it. The instructions and any spare parts or "buttons" are long lost 15 or more years ago, probably 20, and I'd like to set up a rev limiter on this car. What's the best plan for that, sell this thing and get a newer 6al box with the dials? I'd rather keep it since it looks great as is with the Mopar branding on it, but I'd rather protect the engine over that.

I'd also like to replace the MSD distributor with something that's got vacuum advance. I bought this MSD about the same time as the box, back when I knew even less than I do now. What do you experienced folks recommend for a street 440>512 distributor with vacuum advance?

The Mopar Performance P4876728 is an MSD 6AL analog unit that uses the plug-in modules. Supposedly, the module just contains a fixed resistor. The resistance values vary to correspond to the RPM setting of the module. The unit shipped with four modules:

The module plugs into the side:

The modules were/are available in 100 RPM increments such as the following:

MSD also offers selectable modules in a range, or in three selectable settings using three modules:

Summit carries a lot of the MSD modules and accessories.

Attached is the MSD 6 Series (analog) instructions, which should work for the Mopar branded unit.

 

[Spyder]

Awesome, thanks. I'll look on summit for the models tomorrow. That port is currently empty on mine.

Thank you!!

 

[Spyder]

That RPM module selector is exactly what I needed, thanks! Now to figure out distributor...

 

[Mr Cuda]

I have an old MSD soft touch rev limiter with a bunch of "chips".
I put the 7000 rpm one in mine for my 340.
I could look to see what range my extras are.
Your big motor would probably need something lower.

 

[Spyder]

I figure around 54-5600 would do it for safety and longevity. I'm not racing it, just cruising and doing burnouts.