Cummins/Onan 1B Series / 1B Series Plant — Valve service
Repair & overhaul · engine
For the Cummins/Onan 1B Series / 1B Series Plant, from the Cummins/Onan operator's manual.
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Procedure
- Compression readings for cylinder should be 75 to 80 pounds when cranked electrically, and 60 to 65 pounds hand cranked.
- Clean valves and combustion chamber of all carbon.
- Note condition of valves and seats. Valves should be 44°, and valve seats should be ground 45°.
- Use fine grade of valve grinding compound to lightly touch up valve and seat.
- Correct width of seat should be between 3/64 and 1/16 of an inch wide.
- Clean compound from valves and seats. Lubricate valve stems and guides freely with light oil.
- Be sure valves drop of their own weight in their respective guides before assembling.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve angle 44°
- Valve seat ground 45°
- Seat width 3/64 to 1/16 inch
- Compression 75 to 80 pounds electric; 60 to 65 pounds hand cranked
Source: Cummins/Onan 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.