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Hey guys I've had a bunch of people tell me I have a 351 Windsor but the auto shop I brought my truck into said I had a 351m could you guys please help me as I'm in the process of rebuild the internals? I recently repainted the valve covers and some small stuff. Any help is really appreciated thanks again
Definitely not a windsor. Its either a 351m or a 400. pretty hard to tell the difference without checking the stroke as they are identical on the outside. I don't think its a cleveland because of the taller deck height looking at the rib by the distributor. To be sure its not a cleveland which would have been swapped in, the M has 3 motor mount bolts and a C has 2 bolts. Also the top two transmission bolts on an M are spaced at 8" across versus a C at less than 6". 351C was never offered in a truck from the factory.
Engine families can be identified by number of valve cover bolts as follows...
Engine Identification The 351W and 351C did not come stock in 73-9 trucks. Some of them have been "transplanted" tho.
Engine Identification:
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351C/M/400 335 series: 8 bolts in rectangular valve covers. Timing chain housing is part of block. Thermostat housing on block. Exhaust bolt holes diagonal.
351M/400 335 series: intake is 12.7" wide the 351C is narrow. The 351M and 400 are identical externally, only internal parts examination can tell them apart.
351W/302/5.0L 6 bolts on trapezoidal valve covers. Thermostat housing on intake. Exhaust bolt holes horizontal.
429/460 385 series: 7 bolts in rectangular valve cover
352/360/390/427/428 FE series: Intake goes under valve covers.