Found the knock in my stroker...maybe (pics)

[Dedicated5.0]

After almost two years sitting on the floor I finally decided to pull the pan and find the knock in my 5.0 stroker. It started knocking 20k miles after the rebuild. The s-trim had been on it for about 10k miles. I thought that due to the higher compression, 10.2, that I must have gone lean and jackhammered a rod bearing or something (I did hit the limiter once or twice). When I pulled the pan I found a bunch of magnetic chips on the pick-up screen (should have got a pic) and this on number 6...


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Looks like one of those chips got in there and disintegrated. Good news is that the journal looks fine to the naked eye and I can see only the slightest line with a 7x glass.

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All the others looked pretty much like this. Is this normal wear?

Question is, where did the chips come from? Where they there from the rebuild, or from punching the oil pan for the blower return line, or from some other damage in the motor? What else should I be looking for. I'm a rookie and need some guidance. I have not pulled any of the main caps yet. Going to do that next weekend.

[NXcoupe]

If they are magnetic, they are from punching the hole in the pan and then tapping it. The bottom pic is pretty normal wear pattern. That top bearing wouldn't give you much of a knock, it's worn and not in good shape, but doesn't look like it was knocking. JMHO. I would look at your piston to wall clearance with a torque plate on the block.

[Dedicated5.0]

Not enough to cause a knock? Yikes, not only was it knocking but the stock (dummy) oil pressure gage was bouncing back-and-forth at hot idle.

Can I check piston/wall clearance from the bottom with the heads still on? Will a simple feeler gage work? It was assembled with .0035" clearance according to my build sheet.

[NXcoupe]

No, not really. You will need a dial bore gauge. If you bring your rod up here, I can bolt it together and tell you what the oil clearance is on it. If it was over .0035 or so, it will cause a knocking noise. I would check the main bearings and see if there is damage there first.

[Dedicated5.0]

Thanks. I'll look at the mains next. Got to buy some 12-point sockets this week.

What about that journal? Does that kind of minor mark require any significant attention? Seems to me that a little home polish would do the trick. I'm not building a race motor. Just trying to get it running again and learn something along the way. I'm not afraid of buying some new tools if needed.

[NXcoupe]

You will need to mic the journal and see if it is still in spec. If it is small or right around the bottom of the spec, then it will need to be turned to an undersize on all the rod journals. If it is smooth for the most part and at the middle or top of the spec, then take it somewhere and have it professionally polished. Doing it at home is for small nicks and such that don't require much sanding. It is hard to keep it perfectly round using emery cloth in your garage.
As for the knock, mic the journal the rod with the gouge came off of and then you would need to use a dial bore gauge set at that measurement to see how much oil clearance you have. You must also torque the rod bolts to spec before checking with the gauge.
Even if it isn't a race motor, you still want it right.

[Dedicated5.0]

Thanks man. Just so I got this right...

Measure the OD of the journal. Then measure the ID of the rod with bearings installed and bolts torqued. The difference would be my oil clearance, right? The build sheet shows a rod clearance of .002. Is that what I'm looking for?

BTW, what are the journal specs? I'm pretty sure its a SBC SJ standard journal. Google hasn't been much help.

[FMGT1999]

RSCoupe is my hero... :D

Kyle

[NXcoupe]

Thanks man. Just so I got this right...

Measure the OD of the journal. Then measure the ID of the rod with bearings installed and bolts torqued. The difference would be my oil clearance, right? The build sheet shows a rod clearance of .002. Is that what I'm looking for?

BTW, what are the journal specs? I'm pretty sure its a SBC SJ standard journal. Google hasn't been much help.

Kyle you're trippin!

I would just mic the journal and then post or PM me what you find. I can then determine what the diameter tolerance is and go from there. If it is sbc then it will either be 2.1 or 2.0 in diameter.

[Dedicated5.0]

Thanks again. I'll inspect the mains and get some rod journal measurements this weekend.

[Dedicated5.0]

I finally got a chance to look at the mains today.

1, 2, and 4 looked like this.
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5 (thrust bearing).
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3 isn't so good. The journal has just enough of a scratch to catch a fingernail. Can this kind of thing be polished or do I have to turn the crank?
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Thing is that the two bearings/journals with the damage (6 rod, 3 main) are right next to each other. Could they have been causing the knock? How does the oil flow in these motors? Could a chip from the blower install have made it past several journals before damaging finally these two?