Firman WH03662OF — Spark Plug Maintenance
Maintenance · Ignition
For the Firman WH03662OF, from the Firman operator's manual.
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Procedure
- Remove the spark plug boot
- Remove spark plug using provided wrench
- Inspect spark plug for damage; clean with wire brush before reinstalling, replace if damaged
- Adjust electrode gap to 0.020-0.024 in (FIRMAN plug) or 0.028-0.031 in (Champion N9YC)
- Seat spark plug and thread by hand to prevent cross threading
- Tighten plug with provided wrench and reinstall spark plug boot
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Gap 0.020-0 FridayParts $214.68.024 in / 0.5-0.6 mm (FIRMAN P/N 330723001 eBay $9.99)
- Gap 0.028-0.031 in / 0.7-0.8 mm (Champion N9YC)
Source: Firman operator'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.