I have a friend that just bought a 78 ford truck, the ,motor has been swapped in it and can't figure out what it is, it looks alot bigger than a 351 C how can I tell what this thing is, Thanks
If it looks like a bigger version of a Cleveland, then it's either a 351M or a 400. As to which, it's damn near impossible to tell the two apart, the 351M is just a destroked 400. If the original valve covers are present and haven't been swapped the displacement is on the left cover info sticker. I've used a dipstick inserted into a spark plug hole to tell the stroke, but came up with 3 inches on a 400, due to the angles involved as the piston moved down the bore, when rotating the crank by hand. Could also be a 460, if the thermostat housing bolts to the intake, and not the block.