I'm just going through exactly the same scenario, spun a big end - replaced all big end bearings - went for a drive around the block and spun the same bearing (the night before a rally)

I spoke to the guy who does my bottom end machining and he says that 99% of the times you spin a big end bearing you distort the big end on the conrod and in most cases you bend the crankshaft.

So guess what I'm doing tomorrow.....pulling the motor out and checking everything, hopefully I haven't bent the crank.

Without knowing exactly what has been done to the motor, the first thing that I would be checking is the conrod big end and crank for roundness. And a check for bearing clearance of various stages on the conrod bearing using flexi guage or something simular. As long as the crank oiling galleries are all clear oil feed should not be a problem.

I have seen simular problems before. Once it was because a mate had acid cleaned his block and had not washed it out properly afterwards (caustic ate the bearings pretty quickly) and on another occasion the conrods on a motor were not resized correctly causing the conrod to be out of round on the big end.

So I replaced a bad con-rod bearing on my performance A14 (which had rotated in it's housing, blocked the oil galley and proceeded to wear itself out). The crank was okay thank god.

I started her up yesterday and apart from being out of tune she ran really well.

So I come back in today and started her and there is the knocking noise again. Off with the sump, oil pump etc.

I remove the spark plugs and crank her free to hear where the knocking is coming from. I am not convinced but it appears to be another con-rod bearing, it has some clearance either side (laterally) so when you give it a wiggle you can hear a knock.

I took that bearing off and it's looking rather worn. Not drastic but enough to raise the eyebrows.

Now I'm going to step back a bit and look at the bigger picture. Is my engine oiling properly?

Does anyone have a quick-check technique?

I checked the oil galleys when I first built the engine (20psi air) and if I remember correctly the crank is oiled first and the camshaft feeds off the crank feed.

I also have great oil pressure.

Does anyone have any advice or suggestions?

Revhead?