1994 Mustang loud noise then won’t start

Update: Pulled all the rockers, pushrods, and lifters last night. I had 4 bent pushrods, all on intake valves. Cylinder 3 intake pushrod was really bad, and the intake valve is not fully seating.



Looking down the intake runner, it appears that the valve bore is cracked, which I assume is why it’s not closing all the way (see picture, have to look closely).



The rest of the pushrods just had a slight bow but not perfectly straight as they should be. Roller lifters show signs of wear, but I’m not sure what is normal and what is beyond repair honestly (this is the first engine I’ve torn down on my own). I haven’t yet pulled the cam and heads, but I’m going to do that tonight to check for cam lobe wear and if my pistons are still good. The engine still spins pretty freely by hand, so Im hoping the rotating assembly is still good.

RaggedGT said:

Did ya spin the motor over high into rpms?

Click to expand...

When it broke I was around 4500 ish rpm. I’ve never spun it anything over 5500 rpm, but I can’t say the same for the guy before me.

Update: Pulled the passenger side cylinder head, found a stationary piston in cylinder 3. So either broke a rod or a rod bolt. Hopefully the crank/block are salvageable. Time to pull the engine!

Well guys, I got the engine pulled and taken apart over the weekend. The rod journal broke on cylinder 3 and busted the cylinder walls on 3 and 7, so at the very least I need a new block and a few pistons/rods. Every single rod bearing had copper showing, and 3 of the main bearings were the same way so I'm sure that's what caused it to blow. The crank might be able to be saved by a good machinist but it took some damage when it blew. I also measured the stroke just for giggles because I noticed it had hypereutectic pistons and turns out it was actually a 347. So now I'm in somewhat of a pickle as to which is more cost effiecient. Should I:

A) Rebuild what I have with a new block, replace bearings, have my crank turned, and find 2 new pistons/rods that match (hopefully not buy an entire set of 8) OR
B) Find a 351 roller block to build with upgraded pistons?

I wanted to upgrade to some decent aluminum heads anyways, so I plan on doing that whichever way I go. I know that some parts will swap between the two (heads, cams) while others won't (i.e. distributor, lower intake, headers, etc). So I'm curious as to which option will be the most cost efficient considering what I will need to buy for each.