MAJOR PROBLEM

[SlidewaysScott]

ok this is a long story so please bear with me...

Last week I heard a loud tapping noise coming from my engine. After determining that I had an HLA that needed air bled out of it, I read up on how to do it and looked in the FSM. Timing was already perfect before I did this. After I bled it, I put everything together tourqe'd everything to spec. Turned the engine by hand about 10 full rotations to make sure the timing was still ok...and it was DEAD ON. So I finish putting it back together and put new plugs in while I'm at it. Turn the key, starts right up, runs beautiful and smooth and no more tapping, and the timing is definantly right on.

...fast forward to today 2 days later...

My test pipe and clutch line come in, the last 2 things I needed to get it on the road. So first thing I put the test pipe on. Start my car up to see if I have any exhaust leaks but instead I hear a really random "clank" noise from the engine....so now I'm just like GREAT . BUT the car still runs smooth and doesn't act like anything is wrong.

The best way to explain it is, it sounds like something in the engine banging around. To be sure something didn't come loose inside I took the valve cover off again, visually inspected it saw no marks, or anything inside. Checked the timing again, STILL DEAD ON...then I pull the plugs and #4 is bent down and the electrodes touching like the piston is hitting it or maybe a bent valve:



But here's the thing, that noise isn't constant like the piston is hitting it, it sounds like a different spot all the time hence why I thought something came loose, and it's seriously about 10x louder when you listen from under the engine like it's coming from furhter inside the engine or whatever. So just real quick I put a new plug in it. Start it up, HAPPENS AGAIN

I'm so lost and dumbfounded. Does anyone have any clue what the hell can be causing this or what happened to cause this??? I really hope I'm not ****ed, any and all advice and info would be greatly appreciated.

P.S. sorry for the long *** story and everything, I just wanted it to be very detailed for hopefully better results.

:::EDIT:::

forgot to mention it's a redtop sr in a 95' s14

[NISTECH]

not real familier with the insides of an sr but from what you said something came loose in your intake and ended up in cyl number 4. remove the plug and insert a flexible magnet to see if you can get any metal out of it. The type of magnet I use is a welders magnet. It is a magnet on the end of a flexable aluminum rod.

[SlidewaysScott]

I'll try that out, but what I was fearing, and someone else just suggested to me is I may have threw a rod bearing...and I was honestly going to take it on the road for its first test drive today

[180fan]

You've seriously got crap in there. Pull the manifolds and pump in some air in there. Pray it'll get the stuff out. While you're there looking at your intake/exhaust valves, double check to make sure your intake/exhaust valve did not break and land in the cylinder.

If the valves seem ok and the crap doesn't come out, pull the engine and pull the head. You're gonna be doing it anyway soon to figure out what the noise is. If it is indeed rod knock, it's not all that bad. Nothing that a new rod, some new bearings, rewelding/grinding/micropolish won't clear up.

[SlidewaysScott]

To be honest a spun rod bearing was my original idea and I just kept telling myself that the damn nissan bearing curse didnt strike me down, but alas all the evidence points to it. So looks like I might as well just do a full buildup now...sad but now it's going to be even better I suppose...