The 1951-1953 Ford engines and the 1949-1953 Mercury engines incorporated the restrictor into a “T” fitting that also mounted the oil pressure sending unit.The part numbers are 8CM-6073 for the Mercury (on the left in Figure 4) and 1BA-6073 for the Ford (on the right in Figure 4).The fittings pictured incorporate a .060” (approximately) diameter restrictor hole to prevent too much flow through the filter, particularly if the filter element is not installed (ouch! The 1950 and earlier Ford engines with filters used a restrictor like that pictured in the center of Figure 4.The Eaton/Weatherhead catalog still shows a similar replacement part available under catalog number 1215.A recent test at Roadrunner Engineering demonstrated that a stock 1946 to 1953 oil filter with a restrictor flows about a quart and a half of oil per minute through a clean filter under meaningful conditions of oil pressure (55 psi), temperature (180F) and viscosity (15W-40).Thus under the preceding conditions, about 10% of the oil pumped by the stock pump will go through the filter and all the oil in a 5 or 6-quart system will be filtered in less than 5 minutes. Actual flow through the filter will differ from our estimate depending on the actual operating conditions.These units were commonly retrofitted on earlier engines for longer engine life.
Driven by a Power Master alternator that is offset to the driver’s side of the engine to accommodate the triple carb setup, the flathead stroker is packing more punch than the original 6-volt power supply.H&H Flatheads calls this combination its Stage 3 High Performance Kit, and it’s available in either 276ci or 284ci versions.This stroker Flathead lives up to the H&H Flatheads motto: Combining the likes of old time nostalgia with today’s technology and durability.While 100% of the oil is not filtered in one pass, the stock filter is effective nevertheless, filtering all of the oil in about five minutes at highway speeds. Various options for converting to “full flow” or other systems, which filter more of the oil, more of the time, are described in other sources.
Converting to one of these systems has pros and cons, but in my view is not generally worth the effort. The flathead oil pump - pickup screen and the sludge traps within the crankshaft throws are woefully inadequate for oil filtering by modern standards.
How Much Oil Does the Ford Flathead Oil Pump Circulate and How Much Gets Filtered?