Cummins/Onan GTA14 / GTA14 qi 20 NA — Connecting the Timing Light and Adjusting the Timing
Adjustments · Ignition system
For the Cummins/Onan GTA14 / GTA14 qi 20 NA, from the Cummins/Onan owner's manual.
Applies to: Cummins/Onan GTA14 qi 20 NA, Cummins/Onan GTA14 engine
Before you start
- Make sure timing light voltage matches battery source or the timing light will be damaged
Procedure
- Connect timing light induction pick-up clamp around #1 cylinder spark plug secondary wire.
- Connect red power lead to battery positive and black lead to negative.
- Point timing light toward back side of accessory drive pulley to read degrees BTDC.
- Loosen the two ignition generator mounting cap-screws to adjust timing.
- Rotate ignition generator clockwise to advance or counter-clockwise to retard.
- Tighten the two mounting cap-screws.
Tools required
- Low and high-tension timing light Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Initial timing per Table 7-04
- Generally retard/advance 4 degrees per 5000 ft altitude change for natural gas
Full service-parts list: Cummins/Onan GTA14 qi 20 NA →
Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.