How do I tell witch FE engine is in my truck? I was told it was a 390, but on the front driver side under the head parting line it has a 352, I'm think'n it's a 352cu but is this correct?

 

please check out the fe forum. this has been gone over a few times and has the measurements to tell which fe it is. the 352 was cast into all the blocks than the mirror 105 was.

 

other than taking a head off and measuring the bore, the only way to know for sure is to measure stroke. you can do that by pulling a sparkplug and sticcking a thin stick down the hole at TDC, and BDC. 352 and 360s had a stroke of 3.5 inches, 390s had one closer to 3.75. and there are several other engine sizes and strokes, so visit the FE forum.

only diffrence between a 352 and a 360 is .050 bore, so if the motor has had any rebuilds in it's past, it may be closer to a 360