MAIN HOME PAGE > > Technical T O C > General Engine Specs > Ignition Conversion Page 1 > Ignition Tuning for Maximum Performance Special thanks to John B. at: johnb66@aol.com for submitting the following infoIgnition Tuning for Maximum Performance
Tuning for maximum performance assumes the rest of the engine is also suitable for maximum performance. The octane rating of the fuel being used must be sufficient to accommodate the engine's compression ratio. The engine harmonic balancer must have either degree marks or a timing tape which correctly shows up to 60° Before Top Dead Center (BTDC). The carburetor must be properly jetted so that detonation or surging is not caused by the fuel mixture being too lean when the ignition is at maximum advance. The ignition coil and spark plug wires must be able to deliver sufficient spark to fire the plugs under maximum engine loading. If you are unsure about any of the above, consult the Mopar Performance Modification Manual. The manual outlines proper ways to construct a race engine.
If the procedures outlined for maximum performance are followed and the engine begins to detonate, you must decrease the timing advances until detonation is eliminated. Detonation not only severely reduces power, it also destoys pistons, rings and rod bearings. DO NOT RUN AN ENGINE THAT IS DETONATING.
Tools required:
Timing light
3/32 allen wrench
Vacuum gauge with long hose
Vacuum source ("Mighty Mac")
Friend or helper
- Set the basic timing for total mechanical spark advance.
- Disconnect and plug the vacuum hose
- Connect timing light to the battery and #1 spark plug wire
- Loosen the distributor hold-down clamp just enough so that the distributor housing may be rotated by hand.
- Start the engine and allow it to warm fully
- Set the idle speed between 2600 and 2800 RPM
- Set the timing in accordance with the following chart:
Engine Heads Timing Specs A Production - Pre 1989 (iron) 35° BTDC A Production - 1989 & newer (iron) 32° BTDC A W2 (iron) 35° BTDC A W5 (alum) 35° BTDC B/RB Production (iron) 38° BTDC B/RB Stage I, II, III (iron) 38° BTDC B/RB Stage IV, V (iron) 38° BTDC B/RB Satge VI (alum) 38° BTDC B/RB Indy (alum) 35° BTDC B/RB B1 (alum) under 475 cu. in. 37° to 39° BTDC B/RB B1 (alum) over 475 cu. in. under 15.0:1 ratio 36° to 38° BTDC B/RB B1 (alum) over 475 cu. in. over 15.0:1 ratio 34° to 36° BTDC B/RB B1 TS 34° BTDC Hemi All (iron or alum) 35° BTDC
- Tighten the distributor hold-down bolt
- Reduce the idle to original setting, unplug and reconnect the vacuum advance hose.
- Set the vacuum advance for total ignition advance.
- After the basic timing has been set for total mechanical spark advance, disconnect the vacuum advance hose at the carburetor. Connect a vacuum gauge to the carburetor's vacuum advance port and route the gauge and hose into the passenger compartment. Place the agauge in a location where an assistant can read the gauge while the vehicle is being operated.
- With the vehicle in operation, note the maximum amount of vacuum generated by the engine while in gear and being held at a steady speed between 2000 and 4000 RPM.
- Stop the vehicle, turn off the engine and connect a timing light to the battery and #1 spark plug wire.
- Start the engine and raise the idle speed to 2600 RPM. Connect a vacuum source ("Mighty Mac") to the distributor's vacuum canister and draw vacuum up to the reading noted in step "b".
- Note the total advance shown on the harmonic balancer.
- Total advance, mechanical plus vacuum, should be set according to the following chart:
Engine Total advance A 50° BTDC B/RB 56° BTDC Hemi 53° BTDC
- Disconnect the vacuum source and insert a 3/32 inch allen wrench into the internal vacuum canister adjusting screw. Turn the allen screw (clockwise to decrease, counter-clockwise to increase) to obtain the correct setting. Reconnect the vacuum source and re-check the timing. Continue repeating this procedure until the correct setting is obtained.
- Remove the timing light vacuum source. reconnect the vacuum hose. Reset the idle speed to your original setting.
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