Yes Slomo for a generator setup you want be at 3750 off load to have the correct Hz whenever it is connected to electrical items but he ask for the idle speed of the engine and that old breast of a Briggs was designed to have an idle speed of 1750. The spec was found on the engine lookup of the Briggs Power Portal for that spec engine.
Technical Specifications
Model Series | 1974 |
Displacement | 318 |
Oil Capacity | 48 oz (1.4 l) |
Valve Configuration | L-head |
Flywheel Torque | 65 lb/ft (88.0 Nm) |
Governor Arm Torque | 45 lb/in (5.0 Nm) |
Carb Mount | 85 lb/in (9.5 Nm) |
Plug Gap | 0.03 in (0.75 mm) |
Intake Valve | .005-.007 in (.13-.18 mm) |
Exhaust Valve | .009-.011 in (.23-.28 mm) |
Idle Speed | 1750 |
Air Gap | .010-.014 in (.25-.36 mm) |
Flywheel Puller Part | 19165 |
Flywheel Holder Part | 19433 |
Connecting Rod Torque | 185 lb/in (21.0 Nm) |
Sump Torque | 140 lb/in (16.0 Nm) |
Head Torque | 165 lb/in (18.5 Nm) |
Just don't want be idling producing power under load. The OP may have one those generators with idle down mode. I have worked on a couple that had that feature even as old as they were.
The reason for the 3750 spec as an off load spec is the governor droop under load.