can I modify my WUR with this setup??

[ertech]

Hi had an idea but do not know if it is a good one.
since I have a spare solenoid I removed . can I use this MSD part to triger the solenoid at a given RPM the the boost port on the WUR . I would triger it at around 3800RPM where the AFR dips to 9.5?
the rest of my curve is very good so no need to modify the WUR

Thanks and hope I am clear.

[mark houghton]

I use and MSD rpm switch and solenoid for the same purpose, in conjunction with an adjustable WUR. I'm not sure a window switch will work. Don't they have two set points....one to turn something on with, and the other to turn it back off...thus a window of operating range? In other words, if you set the "on" to your desired 3800, it will stay on until you've reached some other higher set point...and if you never hit that set point, it won't turn off - and you don't want that either. What you want is the solenoid to open and stay open at and beyond your setpoint and close when you drop below the setpoint.

[Brent 930]

Wrong module.

[JFairman]

You have the right idea and Mark explained the window switch correctly.

If you like paying MSD around $100 for outdated analog circuitry and the MSD name, and then having to buy a bunch of rpm pills for $30 to make it work the MSD rpm switch is the correct device.

Or you can buy the plain black box modern design digital rpm switch with digital readout from summit racing which needs no pills and is programmable in 10 rpm increments for less than $50. http://www.summitracing.com/parts/SUM-830450/

They both do the same thing... ground an electrical circuit at a set rpm.

[mark houghton]

Originally Posted by JFairman

You have the right idea and Mark explained the window switch correctly.

If you like paying MSD around $100 for outdated analog circuitry and the MSD name, and then having to buy a bunch of rpm pills for $30 to make it work the MSD rpm switch is the correct device.

Or you can buy the plain black box modern design digital rpm switch with digital readout from summit racing which needs no pills and is programmable in 10 rpm increments for less than $50. http://www.summitracing.com/parts/SUM-830450/

They both do the same thing... ground an electrical circuit at a set rpm.

Agreed. Sometimes we just use what we have rattling around in our parts boxes. If buying new I would definitely go with the Summit digital.

Oh...just one more piece of information that people with the old style MSD rpm switches might be interested in. I suspect that those "pills" that must be used to select the rpm are nothing but big resistors. Some time ago I took my entire set of pills and put an ohm meter to them. If I can still find the information I'll post it. A person could probably go down to your local Radio Shack and buy 10 Watt resistors of the proper size in substitution and get around the enormous markup of MSD.
Just call me thrifty....other's call me cheap.

[911st]

Just a thought.

If you have not lowered your WUR control pressure to get more fuel on boost you should not need such.

If it is a stock WUR it may just need service.

[ertech]

one problem I see
it does not get pig rich at the same RPM in 1st 2nd 3rd gear.how do i than set the rpm at?
Thanks

[RarlyL8]

it does not get pig rich at the same RPM in 1st 2nd 3rd gear.how do i than set the rpm at?

That is why it is better to use boost to delay enrichment instead of RPM.