Hey everyone,

Well, I WAS swapping motors out. I got everything put back together on the new motor after the tone ring swap and then I saw that the connecting rod going to my piston #4 had a flaw in it and had to tear it all back down.

I'm trying to get an idea here of what I will be looking at if I go to get machine work but everyone seems to have their own opinion. I have 8 connecting rods form the old motor, and I have one in the new that is bad. What I want to do is take all 8 rods and pistons from the old 4.7 to the machinist, ask him to pick on to replace the bad one in the new engine, then go through and change all my main bearings and all my connecting rod bearings.

I'm a little nervous because I haven't ever had to do machine work on something like this. V8 is normal to me, the 4.7 is not yet. Has anyone here had machine work done on a 4.7l? Even it is was to upgrade to high performance rods? I assume it has been done before.

 

I don't know how much. But I would suggest calling a few places and get an estimate. Machine work varies depending on what work needs to be done. Hopefully it is not that bad.

 

Sorry I didn't see this sooner....

The rods on a 4.7 are scored and cracked, not cut and machined, at least that's what my machinist buddy told me today. That's not necessarily a flaw you're looking at.

 

why dont you just take one rod out of the old motor and swap it for the bad rod?

 

just an idea. was the engine with the bad rod over reved? if so there might be other damage in the engine. that is hard to see just by looking at it. just something to think about.

 

You could just swap out one rod but it may through off the balance of the engine, rods should be balanced as a set so they weigh the same.

This maintains a smooth running and trouble free engine that will last many years

The pistons should be balanced as a set also.

Every engine I custom built I balanced every part and made sure they matched and had the crankshaft balanced also, all valves need to match at deck in height all valve pushrods should match exactly in length and weight if possible

 

 

well i have swapped out a rod or 2 multiple times and as long as they are oem parts they are all suppose to be with in a certain tolerance. i have never had an issue with doing this. now for aftermarket/performance parts it is more important.

 

 

Not sure what is going on here, but thanks for the help. However, this thread is over three and a half years old! Why it is revived, no clue. I did find it funny though, a little late might be an understatement. Anyways, to clarify for people so that all of this misinformation isn't out there, here it goes.

The rod was indeed flawed. There is a chunk of metal missing at the cracked interface. When a rod is cracked and put back together with the connecting rod bolts, it is a very clean edge, almost hard to see. Very precise, when it isn't flawed. Another side note, conecting rod bolts are TTY, they must be replaced if you swap out the rods or tone ring.

That being said, you do not need to balance the 4.7 out, I didn't and I have 90K on the engine since this thread was made. The crank is balanced, and the pistons/rods come as a set, pressed together, and you should not balance them, so don't try. It is a pressed method to creating these rods and they shouldn't be machined on like that. Be careful what information you pass out before you cost someone between $100-$200 to go buy a new piston /rod set from the dealer.

sl2, you are correct. The rod/pistons are held to a tolerance at the factory and anything OEM will be fine from the factory. Aftermarket is aftermarket and needs to be looked at differently.