i am building a 79 400 to go in my 66 f100. i just got the block back from the machine shop along with the rods and pistons and a new crank kit. the guys at the shop told me that the rods were fine and the block did not need to be line bored or decked but the crank did need to be ground. so i just bit the bullet and bought a crank kit that came with rod and main bearings. my question is about the bearing clearances. i checked the mains and everything seems good, green plastigauge read at .003. then i installed the rod bearings and when i checked the clearances on the #1 piston and rod the plastigauge read .002 on the right side of the bearing and .015 on the left side of the bearing. it also concerns me that there is a small amount of play if i move the rod side to side. this is my first build and i am referencing the book "How to build Ford V8's" by Tom Monroe. i just want to be sure every thing is sound in this motor so i dont end up with a 3000 dollar boat anchor. thanks for any help

 

Try the 400 engine forum. The guys that build those engines will answer there.

 

You want between .002 and .003 for tolerances, and yes a little play is normal.

 

.002 is right where you want to be. I'd let .0018 go, no more than .0025 max. You need to check the crank size first to see if it's on the high side or low. Then have the rods resized accordingly. Then fit your bearings. Sealed Power rod bearings usually are tighter than Clevite if you run into problems. Get a hold of a good bore gage that reads in .0001" to check your clearances. A bearing shouldn't be tiped any more than .0002" in the rod ( edge to edge ).