Technical Sheet on Sprint Tachometers and MSD Ignition Systems. How to Install a Sprint Tachometer With a MSD 6A Ignition System

Transcription

1 Technical Sheet on Sprint Tachometers and MSD Ignition Systems How to Install a Sprint Tachometer With a MSD 6A Ignition System

2 Step 1: Wiring Procedures Sprint Tachometers are voltage-triggered tachometers rather than being current-triggered tachometers such as stock units. IMPORTANT: DO NOT INSTALL BEFORE READING INSTRUCTIONS CAREFULLY. Your Sprint Tachometer has been carefully assembled, calibrated and tested before being packaged and shipped to you. Our instructions are carefully documented and are the result of our experience with thousands of installations of Sprint Tachometers. We hope you will follow these instructions carefully and explicitly to achieve the best results with this quality product. 1) Locate the Tachometer Filter packed with the tachometer. This Filter will be a round 5/8 x 1 in length and constructed of black plastic. Three color-coded wires (brown, purple and white) will be projecting from one end. 2) Connect the brown wire of the Filter to the brown wire of the Tachometer. 3) Connect the purple wire of the Filter to a metal bolt on the Engine Block. DO NOT connect this wire to either the GND wire of the tach or to any other common-ground connection behind the dash. 4) Connect the black wire from the Tachometer to a good ground point on the dash panel. 5) Connect the red wire from the Tachometer to the Scotch-Lok splice and then tap into the red with green stripe wire of your engine harness (from the rear of the ignition switch). Connecting to MSD Ignition Systems: The procedures outlined below will usually be the proper method for connecting the Sprint Tach to the most common MSD system the MSD-6A having a Blaster-2 Coil.

3 With the brown and purple filter wires already connected exactly as described in the paragraphs above, start the vehicle and let the engine idle. With someone in the car to watch the tachometer dial and to increase the engine speed, touch the end of the white wire of the Tach Filter to the minus (-) side of the MSD Blaster-2 Coil. The tachometer should now show a reading approximating the engine speed in RPMs (revolutions per minute). If the tachometer reading is correct at idle, gradually increase engine speed from idle to 3,000 to 4,000 revolutions. The tach reading should increase accordingly. If the tach reading does not increase or drops to a zero reading, do the following: Remove the white wire from the coil connection you first assumed was the minus (-) side (and normally the distributor side) and touch the end of the white wire to the other (small) terminal of the Coil. If no reading at all shows on the tach or engine speed begins to falter or drop off, go to the next paragraph. Remove the white wire from the Coil connection and with the engine still idling, touch the same white wire to the Tach Outlet connection terminal located on the side or end of the MSD 6-A box. You will probably now see a reading on the tachometer at idle. Increase the engine speed while monitoring the tach reading. If the reading tracks properly up to 2,500 or higher, but then drops off as engine speed is increased further, continue on with the steps outlined below. Disconnect the white wire from the MSD 6-A box. Disconnect the brown wire of the Tach Filter from the brown wire of the Sprint tachometer.

4 With the engine again at idle, touch the end of the brown wire of the Sprint Tach directly to the Tach Outlet terminal on the MSD 6-A box. A correct RPM reading at idle should now register on the tachometer. Caution: Do Not by-pass the Tach Filter UNLESS all of the above steps have been followed precisely. Gradually increase the engine speed to higher RPMs while watching the tach reading. If the tach pointer tracks correctly over the full engine RPM range, shut the engine off. You may now permanently connect the brown wire of the Sprint Tachometer to the Tach Outlet terminal on the MSD box. Next, disconnect the purple wire of the Tach Filter from the engine-block mounting point and remove the Tach Filter from the vehicle since it will no longer be able to be used in your installation. Should your Sprint Tachometer not respond properly after all the above steps and procedures are followed, your MSD system may require a special Tach Adapter 8910 or This unit is available through your MSD Division of Autotronics Controls dealer and instructions for installing the Adapters should be included with the part. This item is NOT manufactured by nor is it available through Dearborn Classics. It is our experience that only a very small number (estimated less than 2%) of vehicle owners and builders with our Sprint tachometer and a MSD Ignition system such as the MSD 6-A will ever require the MSD 8910 or 8920 Tach Adapter to be purchased and installed.

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