ive came across motor that is suppose to be a 5.3, its out of a tahoe but has flat tops? and its not that h.o motor cause its still an iron block, any way i can tell?

 

Sounds like a 4.8...

 

If the heads are off of it, rotate it till one piston is at top dead center, then rotate it again till that same piston is at the bottom of the bore. Then just measure the difference, this will be your stroke. A 5.3L will have a 3.622" stroke, while a 4.8L will have a 3.267" stroke. Basically a 1/2" of difference, so you should be able to tell.

 

alright thanks man...