400 or 351M?
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From: Honkytonkville
400 or 351M?
Haha- I know how lovely a question this is, but some guy out by me is selling an 83 F150 4x4 for $500. It runs well, trannys good, clutch feels strong, 4x4 works, decent tires. doors are pretty much gone, but back to the question at hand....any way to check if motor is 351M or 400- I know this late of a tuck should be a windsor if anything but this motor was obviously switched in because it did show 8 valve cover bolts(only a 400 351M or 351C have 8). The window sign says 351M/400, and when I asked the guy he said the same so he obviously doesn't know himself. I'm not terribly familiar with 351m or 400 motors, so any help would be great!
Thanks
Scott
Thanks
Scott
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From: Delaware
You cannot tell a 351M from a 400 from the casting #. They both use the same block. You cannot tell them apart externally at all.
The only way to tell without disassembling the motor is to remove a spark plug, insert a wire into the cylinder and rotate the crank(by hand) to TDC or BDC on that cylinder. Mark the wire, then rotate the crank again to BDC or TDC. Mark the wire again. The 351M will show ~3.5" between marks on the wire. The 400 will show ~4.0" on the wire.
Here is some Engine Identification information that I copied from another thread.
Engine Identification:
======================
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 10.7" wide the 351c is narrow.
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.
The only way to tell without disassembling the motor is to remove a spark plug, insert a wire into the cylinder and rotate the crank(by hand) to TDC or BDC on that cylinder. Mark the wire, then rotate the crank again to BDC or TDC. Mark the wire again. The 351M will show ~3.5" between marks on the wire. The 400 will show ~4.0" on the wire.
Here is some Engine Identification information that I copied from another thread.
Engine Identification:
======================
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 10.7" wide the 351c is narrow.
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.
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From: Honkytonkville
I can tell simply by the bolts on the valve covers which family the motor belongs, because with ford each family has a different number. I just didn't know if there was any way to tell the difference between 351M & 400. Can we clarify if there is for sure a way to tell the difference externally between the 351m and 400?
Scott
Scott
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Joined: Aug 2001
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From: Delaware
There is no way to tell the difference between a 351M and a 400 externally, because there is no difference.
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From: Honkytonkville
Well folks- I did some further research this evening and discovered what the deal was with this pickup- It is a stock 351M, with a 400 crank, makin it a 400. The guy kept saying " it's a 351 modified to a 400" so finally I asked how it was modified to a 400- he said it had a stroker 400 crank. Sounds like he was downing some a grandpas cough medicine, and didnt really know what the helll was going on. But, I did find out that motor was swapped in and it used to be a 302. 4x4 works. Sounds like a deal- but I'm gonna refrain this time- I need something that will haul my mud trucks and I dont think this will get the job b/c he was telling me that it was squatting with a ford 8N on it. I'm gonna keep lookin!! Thanks for all of your help!!
Scott
Scott
