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Jack Shaft · 07-15-2020, 08:36 AM

Ford engineers were pretty sharp,they designed the drain back tube to handle the flow of oil through the rear main bearing with a clearance up to about .0025 or so..exceed the clearance more oil can flow by,'overwhelming the tube diameter and subsequently leaking out the flywheel housing weep hole.

Journal bearings rely on the hydrodynamic principle to support the crankshaft on a cushion of oil.the principle is a constant,.001 per inch of crankshaft diameter,model a crankshaft journal is about 1 1/2 inch diameter? oil clearance .0015. gravity fed or pressurized the principle is constant..

Adding a larger drain capacity doesn't hurt as long as you check your bearings periodically.I prefer an oil spot on the garage floor informing me that my clearances are too wide,Im old,need reminders..

07-15-2020, 08:36 AM	#13
Jack Shaft BANNED Join Date: Dec 2019 Posts: 1,196	Re: Rear Main Bearing Drain Ford engineers were pretty sharp,they designed the drain back tube to handle the flow of oil through the rear main bearing with a clearance up to about .0025 or so..exceed the clearance more oil can flow by,'overwhelming the tube diameter and subsequently leaking out the flywheel housing weep hole. Journal bearings rely on the hydrodynamic principle to support the crankshaft on a cushion of oil.the principle is a constant,.001 per inch of crankshaft diameter,model a crankshaft journal is about 1 1/2 inch diameter? oil clearance .0015. gravity fed or pressurized the principle is constant.. Adding a larger drain capacity doesn't hurt as long as you check your bearings periodically.I prefer an oil spot on the garage floor informing me that my clearances are too wide,Im old,need reminders..