Adjust tickover and max revs

[smchris]

Hello everyone

Can someone please guide me to where the adjustments are found to set the tickover speed and the max engine speed on the Super Major?

The engine is hunting a tiny bit at lowest revs; I tried adjusting the governor tension, but it doesn't affect things so I think it's just running too slowly (it's sitting at 500 rpm and is happier at about 600); what's the correct way to adjust this up?

Cheers

Chris

[Emiel]

Hi,

Assuming it’s pneumatically governed, then on the adjustment screws on the inlet manifold.

[Billy26F5]

Before adjusting the revs you need to adjust the damping valve on the front of the governor, it will affect the engine speed, but you should notice an improvement, there should be no hunting at 540 rpm (or any other revs) once you've adjusted this valve correctly. If it gets worse turning it one way you'll need to go the other way. then adjust the idling screw on the manifold to 550 rpm and the no load screw to 1900 rpm.
With a minimec the no load speed is 1810 rpm, and the screws are on the governor rear, but if a minimec is hunting it probably needs an overhaul of sorts.
Sandy

[smchris]

Thanks. It's a Simms pump, not minimec. I have tried adjusting the tensioner on the governor and it still runs a bit unevenly at tickover. We're not talking horrible departures in revs, but a definite rise and fall. It's a new symptom - it was running fine about 12m ago after I replaced a torn governor diaphragm, so seems likely something else is playing up. Possible that air is leaking around the tensioner bolt locking nut.

Meanwhile, where is the idling screw you mention?

[John b]

Hi Chris, number 9 on the drawing are the idle and maximum rpm adjusting screws, the lower one sets the idle speed

[smchris]

Thanks a million.

Any ideas what else would make it run a bit unevenly at low revs out of the blue? Fuel's clean, lines are clear, air cleaner not clogged...

[Billy26F5]

Keep adjusting it, there is one point where it should stabilize, if you run out of adjustment I recommend you check the damping valve piston, Super Billy's one was out of the hole in the bolt, needing more parts to fix the governor. The bolt and piston are not availabe new.
Sandy

[smchris]

Thanks Sandy, but I don't think that's the issue; I reassembled it well last summer and the parts were not worn; also, problem is new and I cannot see how the piston would dislodge in the interim without dismantling or undoing the bolts, which has not happened. I might investigate to see if the manifold flap is loose or something; if that's wavering a bit under the high pressure at low speed, it could wobble and cause this symptom. It's very minor uneven running...

[Billy26F5]

I think dirt is more likely to be the cause, it could have partially blocked the bleed governor pipe causing the sort of trouble you're having. I suggest you check both governor pipes while you're there.
Sandy