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Bored&Stroked · 10-24-2023, 05:11 PM

Full Flow - Additional Details: It isn't necessarily true that there is always a percentage of unfiltered oil pumped through the bearings. On a flathead Ford, there has always been a residual pressure release valve either in the block (up front in the valley) or in the pump to relieve/control oil pressure.

Given this, one can run a full-flow filter that does not have a pressure relief valve in it. This guarantees that all oil going through the filter is never bypassed.

Systems called 95% Full Flow: Many of the supposed "full-flow" conversions do not have a specially modified oil-pump (where the oil exits the pump through the side of the pan). Instead, the cross-over oil galley (above the pump) is blocked off and the oil is routed through a full-flow filter - then back into the main galley on the other side of the blocked off one.

However, in these systems the rear main has its own supply that doesn't rely on the cross-over galley. This means the rear-main is not filtered in these conversions. I disagree with the 95% nomenclature - that is over optimistic in my mind.

I call these systems 66% filtration.

10-24-2023, 05:11 PM	#4
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,910	Re: WTB Full Flow Oil Conversion Kit *Full Flow - Additional Details:* It isn't necessarily true that there is always a percentage of unfiltered oil pumped through the bearings. On a flathead Ford, there has always been a residual pressure release valve either in the block (up front in the valley) or in the pump to relieve/control oil pressure. Given this, one can run a full-flow filter that does not have a pressure relief valve in it. This guarantees that all oil going through the filter is never bypassed. *Systems called 95% Full Flow:* Many of the supposed "full-flow" conversions do not have a specially modified oil-pump (where the oil exits the pump through the side of the pan). Instead, the cross-over oil galley (above the pump) is blocked off and the oil is routed through a full-flow filter - then back into the main galley on the other side of the blocked off one. However, in these systems the rear main has its own supply that doesn't rely on the cross-over galley. This means the rear-main is not filtered in these conversions. I disagree with the 95% nomenclature - that is over optimistic in my mind. I call these systems 66% filtration.