Lotus Elan

Dry Sump Pump Drive Gear Lubrication

PostPost by: JonnyPlus2 » Fri Mar 17, 2023 5:00 pm

Afternoon Lads!

On page 38 of Tuning Twin Cam Fords, David Vizard states "It is possible . . . to get very little lubrication on the (dry sump) oil pump drive gears . . . " He then goes on to describe (with a drawing) how to drill a fifty thou. hole to supply a tiny jet of oil to the gears. This very likely in the context of a four port pump as a few pages later he describes boring out and tapping the oil pressure switch hole to accommodate the high pressure feed from the pump to the oil galleries.

Before I drill the hole to lubricate the drive gears, I'd like to know:
Is this still necessary if I'm using a current five port pump?
Also why are bronze gears offered as an option for the dry sump pump gears?

Thanks much for your time.
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PostPost by: StressCraxx » Sat Mar 18, 2023 2:38 am

It's really not necessary to drill the hole. The gears are lubricated with the oil they pump. I've been running the same oil pump for more than 8 years without fail. I do use 20W-50 wt oil during pump assembly. I fill the system and then loosen the fitting at the pressure pump inlet and make sure the air is completely bled from the supply hose to the pump. Spin the engine on the starter without spark plugs in. I get oil pressure at the gauge within about 40-60 seconds or less. Been doing that for almost 20 years.
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PostPost by: rgh0 » Sat Mar 18, 2023 3:34 am

I agree that while it probably will not hurt to drill the hole it is also not really necessary. There is a constant oil mist inside the engine block and the layshaft gears to the oil pump and distributor get enough lubrication from this.

Brass on steel or cast iron gears have better wear characteristics and are typically used in worm gears for that reason where you have a high sliding velocity between the gear teeth. It is not critical to use brass in this sort of right angle helical gear drive. Again it probably does not hurt but probably is not needed.

cheers
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PostPost by: JonnyPlus2 » Sat Mar 18, 2023 4:24 am

I thought that the hole was perhaps overkill, but I'm glad I asked as experience is the best teacher. Thanks for sharing yours with me,
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PostPost by: 2cams70 » Sat Mar 18, 2023 7:18 am

There’s a lot of different gear material combinations available for both the camshaft or jackshaft and the oil pump drive on these engines. Each must have its purpose but so far I’ve never heard a good explanation of what is best to use under which circumstances. Brass gears will suffer from a higher wear rate however. Maybe ok on a race engine but probably not what you want on a road engine.
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