PN8360 MALLORY | Alldatasheet

Document overview

  • Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
  • PDF pages: 8

Technical content

MSD Pro-Billet Ready-to-Run Distributor Chevrolet V8, PN 8360 Chevrolet 348, 409, PN 8393 Chevrolet 409 Aluminum Block Only, PN 83931 WARNING: Before installing the MSD Ready to Run Distributor, disconnect the battery cables. When disconnecting the battery cables, always remove the Negative (-) cable first and install it last. Parts Included: 1 - Pro-Billet Distributor 1 - Rotor, PN 8467 1 - Distributor Cap, PN 8433 1 - Wire Retainer 2 - 1.5" Self Tapping Screws 2 - 10-32 x 3/4" Socket Head Screws Note: The terminals of this Ready-to-Run Distributor require spark plug style terminals. You may need to change the terminals and boots of your wires. MSD offers two kits, PN 8849 or PN 8848 that are supplied with nine boots and terminals. Note: If the gear is ever replaced, MSD Gear (PN 8531) is required for replacement due to the .500" diameter shaft. TIMING FUNCTIONS Before continuing with the installation, here are a few definitions you should be aware of: Initial Timing: This is the base timing (also referred to as idle timing) of the engine before the centrifugal advance begins. Centrifugal Advance: The centrifugal (or mechanical) advance mechanism is made up of weights, springs, advance cams, and an advance stop bushing. The amount and rate of advance that your distributor is capable of is determined by the centrifugal timing. If you ever wish to lock out the centrifugal advance, refer to the centrifugal advance section. Total Timing: This is the total of the initial timing plus the centrifugal advance added together. Example: 10° Initial + 25° centrifugal = 35° Total Timing. (When checking Total timing, disconnect and cap the vacuum canister and plug the vacuum line.) Vacuum Advance: The vacuum advance will advance the timing up to approximately 12° during partial throttle driving (with 15 lbs. of vacuum). The vacuum line should be routed to a ported vacuum outlet above the throttle plates. Note: MSD Distributors are supplied with the heavy (slow) advance springs and the 21° stop bushing installed. This is to prevent detonation in certain applications. Review the information on pages 2-4 to determine the best advance curve for your application. RPM LIMIT AND TACHOMETER INFORMATION Tach Signal: The Ready-to-Run Distributor features a Gray Tach Output wire which provides a clean signal for most tachometers and even some aftermarket fuel injection systems. The signal output is a 12 volt square wave, 20° duty cycle. This wire is also responsible for programming the built-in rev limiter. 1 - Advance Kit 1 - 3-Pin Harness 1 - Gasket 1 - Tube of Gear Lubricant 2 - O-Rings 1 - Vacuum Advance Lock-Out Kit 1 - Gray Tach Jumper MSD • WWW.MSDPERFORMANCE.COM • (915) 857-5200 • FAX (915) 857-3344 ONLINE PRODUCT REGISTRATION: Register your MSD product online. Registering your product will help if there is ever a warranty issue with your product and helps the MSD R&D team create new products that you ask for! Go to www.msdperformance.com/registration.

2 INSTALLATION INSTRUCTIONS

MSD • WWW.MSDPERFORMANCE.COM • (915) 857-5200 • FAX (915) 857-3344 Rev Limiter: The Ready-to-Run Distributor has a built-in rev limit that can easily be adjusted from 2,000 rpm to over 10,000 rpm. The default is 10,000 rpm. To set the rev limiter, run the engine to half the desired rpm then ground the Gray Tach wire (a jumper is supplied) for approximately one second. See page 7 for the programming procedure. CHOOSING AN ADVANCE CURVE The function of the advance curve is to match the ignition timing to the burning rate of the fuel and speed (rpm) of the engine. Any factor that changes the burning rate of the fuel or the engine speed can cause a need for an ignition timing change. Figure 1 shows some of the factors that will affect engine timing. FACTOR Advance Timing Retard Timing For For C ylinder Pressure Low High Vacuum High Low Energy of Ignition Low High Fuel Octane High Low Mixture (Air/Fuel) Rich Lean Temperature Cool Hot Combustion Chamber Shape Open Compact Spark Plug Location Offset Center Combustion Turbulence Low High Load Light Heavy Figure 1 Ignition Timing Factors. As you can see from the chart, most factors will change throughout the range of the engine operation. The timing mechanism of the distributor must make timing changes based on these factors. Example: An engine has 11:1 compression with a high energy ignition. With the specifications given, you will have to retard the timing for the high compression and high energy ignition. By comparing the engine’s specifications against the chart, a usable timing guideline can be found. Engines with a combination of items from both columns will require a timing that is set in the mid range. Obviously a full technical explanation of correct ignition timing would be very complicated. The best way to arrive at a suitable ignition curve for your engine is to use the Ignition Timing Factors Chart as a guide and compare it to the Advance Graphs in Figure 4 until a suitable curve is found. When selecting your advance curve, use detonation (engine ping) as an indicator of too much advance, and a decrease in power as an indicator of too little advance. TIPS ON SELECTING AN ADVANCE CURVE

  • Use as much initial advance as possible without encountering excessive starter load.
  • Start the centrifugal advance just above the idle rpm.
  • The starting point of the centrifugal advance curve is controlled by the installed length and tension of the spring.
  • How quickly the centrifugal advance (slope) comes in is controlled by the spring stiffness. The stiffer the spring, the slower the advance curve.
  • The amount of advance is controlled by the advance bushing. The bigger the bushing, the smaller the amount of advance. CENTRIFUGAL ADVANCE CURVE SELECTING THE ADVANCE SPRINGS The rate, or how quick the advance comes in is determined by the type of springs which are installed on the distributor. The MSD distributors are equipped with two Heavy Silver springs installed. These will give you the slowest advance curve possible (Figure 2). The parts kit contains two additional sets

4 INSTALLATION INSTRUCTIONS

MSD • WWW.MSDPERFORMANCE.COM • (915) 857-5200 • FAX (915) 857-3344 Figure 6 Changing the Advance Stop Bushing. SELECTING THE ADVANCE STOP BUSHING Five different advance stop bushings are supplied in the distributor kit. The distributor comes with a Blue (21°) bushing already installed. If a different amount of centrifugal advance is desired, follow the next procedure to change the bushings. The chart in Figure 5 gives the size and approximate degrees for the co CHANGING THE ADVANCE STOP BUSHINGS 1. Remove the distributor cap and rotor. 2. Remove the locknut and washer on the bottom of the advance assembly (Figure 6). 3. Remove the bushing and install the new one. Install the washer and locknut. LOCKING OUT THE CENTRIFUGAL ADVANCE 1. Remove the advance springs, weights and the advance stop bushing from the advance assembly. 2. Remove the roll-pin from the drive gear and remove the gear from the shaft. 3. Slide the shaft two inches out of the housing. 4. Rotate the shaft 180° and insert the advance stop bushing pin into the small hole on the advance plate (Figure 7). 5. Install the locknut and washer to the advance stop bushing pin. 6. Install the drive gear and roll-pin. Note: If you want to lock out the vacuum advance, see page 7. Figure 6 Locking Out the Centrifugal Advance. Figure 7 Locking Out the Advance. Figure 5 Advance Stop Bushing Chart. BUSHING SIZE APPROXIMATE CRANKSHAFT DEGREES Red-Smallest 28 Silver 25 Green 23 Blue 21 Purple 19 Black-Largest 18

6 INSTALLATION INSTRUCTIONS

MSD • WWW.MSDPERFORMANCE.COM • (915) 857-5200 • FAX (915) 857-3344 Figure 10 Wiring the Ready-to-Run Chevrolet Distributor. GRAY TO TACH INPUT GRAY TO TACH INPUT Figure 11 Connecting an MSD Ignition Control to the Ready-to-Run Distributor. RED ORANGE BLACK NOTE: THE READY-TO-RUN DISTRIBUTORS DO NOT REQUIRE AN MSD IGNITION, THOUGH THEY CAN BE USED WITH ONE. TO COIL POSITIVE + 12 VOLTS TO COIL NEGATIVE - TO ENGINE GROUND FOR VACUUM ADVANCE, CONNECT TO A PORTED VACUUM SOURCE FOR VACUUM ADVANCE, CONNECT TO A PORTED VACUUM SOURCE