How to convert your 86-88 RX-7 secondary ports from exhaust pressure to RPM activation.

What you will need:

- 4 feet 3/16" ID fuel line or silicone line $3 Hardware store

- 5 hose clamps for that size line $2 Autozone

- 3 hose barbs (1/8" MPT thread and 3/16" barb) $2 Hardware store

-1 double sided 3/16" barb with integrated spacer

-1 Mini Mac 3 way solenoid operated valve with 1/8" NPT ports $45 +5 to ship

-1 MSD RPM Swich configred for FOUR CYLINDER operation $48.50 +10 to ship Summit PN-MSD-8950

-1 piece of 1/16" or 1/8" plastic ( 3/4" x 1 1/2") Wherever

-3 zip ties 6" in length $.20

-18 gauge wire, wire connectors, one small male bullet type connector $3

-5/16" vacuum cap

-double sided foam tape to mount valve

Total = $115.20 before tax

You may be able to find a cheaper valve, but the mini mac looks sweet and was amongst the least expensive I came across without looking in a junk yard for EGR valves.

 

Instructions:

Cut the hose into three sections. Making sure to give yourself enough length to mount the valve at your desired location. Disconnect the vacuum line from the actuator tube and cap the hose from the split air pipe.

Assemble as shown below.
The RPM switch comes with wiring instructions. If you choose to use an MSD type switch, you will need to set it for 4 cylinder operation, and use the Trailing coil tach output (yellow w/blue stripe wire) It may be required to send the switch to MSD to have the configuration changed.

••If you use the Summit switch, you will need to use the Trailing coil Tach output wire; however, it has come to my attention the Summit switch is configured for an 8 cylinder type ignition signal and will limit your adjustability to 4000-19600 RPM using the dip switches.

Both coils have a tachometer output with a female bullet type connector.

Wiring is easiest when mounting the switch near the battery. Using the leading coil power wire, since it is ignition switched, then using the positive and negative leads on the battery.

Summit Racing RPM Switch Mounted-this is where I mounted my switch to make access and wiring easier.

Summit Racing RPM Switch with cover off

It does not matter which wire on the valve is positive or negative, it will work either way.

I used double sided tape to mount my solenoid valve to the passenger side strut tower, as finding a place to drill into would be challenging and possibly rust. Mount the valve so the black portion points down, this way the hose barbs face the places the hoses will attach to.

Mini-Mac Solenoid Mounted- this gives you an idea as to where I mounted my valve and why.

Actuator Air inlet Tube - this will give you a look as to where the port activation tube is.
To tap into the main air hose:

Puncture the main air hose with a nail and insert one side of the double-sided barb into the hose. Use silicone sealant to create an air tight fit. Drill a 1/4" hole in the center the small piece of plastic and notch the sides to help hold the zip ties in place as shown below. This will be used to secure the double-sided bard to the hose.
Those who wish to use this design but no longer have an ACV will need to purchase a valve similar to a garden hose in diameter to cap the end on the main air hose to vent pressure from the air pump . The air pump must maintain a minimum of 2 psi at your desired RPM to operate the port actuators.

Note- If you experience sluggish ports or delayed opening of the ports, it may help to install a ball valve in the split air pipe to help increase line pressure. By partially obstructing the flow of air to the exhaust, the air pressure can e raised enough at the main air tube to help open the ports in a more responsive manner.