I just bought a 76 f250, the seller was told the engine was a rebuild 390 high performance but it has the 428 emblem. how do i find out which engine it does have?
be aware i am a master carpenter and an mechanical idiot!

here is a link to a video of the truck i bought on youtube:
https://www.youtube.com/watch?v=JDeu...ature=youtu.be

any comments would be appreciated.

 

I don't know if there's an obvious external way to differentiate between FE engines, but the stroke will be different between those two: if you drop a thin rod down the spark plug hole and turn the engine over by hand to measure the stroke, that should let you know.

The 390 has a stroke of 3.78" and the 428 has a stroke of 3.98".

 

to be really sure drop the pan and let us know the crank numbers

 

So what they are saying is, any mouth breather that goes by the name of Toyota Man can slap a badge on something and call it what it is not. The easy way to do it, is with the spark plug removed and use a rod to measure the stroke, like bkaul said. Just to be totally safe, unhook the battery. Since the engine was rebuilt and you was not around for it, there is no telling what is in that block. Once you know your stroke, you will have a good idea of the engine size. Just my 2 cents.

 

On the fe engines you can line up the timing mark to zero on the balancer (tdc) then spin out the number 1 and number 4 spark plugs. Both atr on passenger side, number 1 is the front cylinder, number 4 is the rear cylinder.

These 2 are exactly 180 degrees from each other on the crank. Use a thin rod or stiff wire, poke down the plug hole to the top of piston. Use the valve cover edge as a marking reference. Mark the rod on number 1, then poke the same rod down number 4 and mark again the same way.

Measure the distance between the 2 marks, that is your stroke.