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FORD BRONCO -> ENGINE & COOLING; swaps, specs, snorkels, vac. diagrams... -> Crankshaft & Main Bearings
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Although we initially developed this site for 78-96 Big Broncos, information in many Links also applies to F, E Series & Cars. UPDATE; all Links via web.archive may be down; Copy orig. URL & go to to search for the new archived copy
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5.0L Thrust Bearing or Crankshaft Premature Wear, Metal to Metal Sound, Due to Torque Converter Flexing in AOD Transmission TSB 92-18-6 for 82-90 Bronco, E & F Series, & Many Others
New Longer Main Bearing Cap Bolts & Studs TSB 93-25-11 for 4.9L in 93-94 Bronco, F Series & Econoline
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351M & 400M Crankshaft Casting Marks Location, pic & Info; "...Cleveland Foundry (CF) mark on #1 main bearing cap. Main bearing caps #1 through #4 are marked with the position number, an arrow pointing toward the front of the engine, a foundry mark, and sometimes a date code. The date code on this cap is 8F12 (June 12, 1978). Crankshaft ID code (1KA) for a 351M crankshaft. The 351M ID code is cast into the side of the first counterweight. Just below the casting ID code in the picture is a letter "H" stamped into a machined surface. That is probably a quality control mark. (and 3.) Machined and drilled parts of the rear crankshaft counterweight. These are adjustments to balance the crankshaft at the factory. Cleveland Foundry (CF) mark on #5 main bearing cap. The #5 main bearing cap is usually not marked because it is unique, wider than the other main bearing caps, with a groove for the rear main seal. Note that the main bearing cap in this D7TE engine is the original 400 design from 1971 (D1AE-AA)..."
Source: by Bubba (Dave R) at via
400 & 351M Crankshaft Visual Identification
Source: by Tim M at
Bearing, Thrust Washer & Rod Sets, Federal Mogul Specs, Bronco & Ford, many engines and years
Source: by Federal-Mogul
General Engine Specifications in 96 Bronco & F-Series from 1996 All F-150, F-250, F-350, F-Super Duty and Bronco Vehicles Equipped with 4.9L, 5.0L, 5.8L or 7.5L Gasoline Engines, & 7.3L Diesel Engines Workshop Manual
Source: by Ford via
Main Bearing Locating Notch in 351W & 351M-400M in 77-79; "From time to time we have encountered questions regarding the lug location on the lower flange bearing for these applications. The questions are primarily with the 1978 351M-400 engines. Through 1976 Ford used only a full grooved flange bearing consisting of 2 identical pieces, our MB-2558P. In 1977, Ford went to partial grooved main bearings with a different lug location for all positions. However, the severe duty applications continued to use the full grooved flange bearings because it allowed for a larger volume of oil to flow to the thrust surfaces. The other positions remained partial grooved. During the above mentioned time period, the main caps for position #3 were made with two locating lug notches to permit the engines to be built with either full grooved or partial grooved flanged bearings. This practice continued until 1979 when Ford then reverted back to the use of full grooved flange bearings in all of the engines mentioned above. Ford currently lists only the full grooved flange main bearing, there are no longer any listings for a partial grooved flange for any model year of the above mentioned engines. All the information we have and the engines we have looked at show that Ford still continues to build these engines with two locating notches in the cap half of the number 3 position. However, on occasion we have had reports from installers who have encountered engines with only one locating notch in the cap half of position #3. As mentioned above these have all involved 1978 351M-400 engines but potentially this could be encountered on any of these engines from 1977-79. If you have a customer who encounters this situation we advise renotching the number 3 main bearing cap to correspond with the locating lug in MB-2558P. We will be adding an Instruction Sheet to these main sets to advise the installers of this procedure should they encounter one of these engines with only one locating notch..."
Source: by
New Longer Main Bearing Cap Bolts & Studs TSB 93-25-11 for 4.9L in 93-94 Bronco, F Series & Econoline
Source: by Ford via Chilton
Piston, Ring, Rod & Bearing Specifications, Bronco & Ford
Source: by Federal-Mogul