I've been trying to find the source of a noise in my motor. It's a 460 backed by a C6 trans. The engine only has about 100 miles on it, has great compression, no smoke, idles fine, fantastic throttle response... It sounded like a rod knock(very quiet almost a valve tick at idle and a loud banging sound when under load), but I thought it was coming from the bellhousing. I pulled the trans a total of 8 times....new flexplate, new converter, new transmission....the noise still didn't go away. I pulled the engine this week and tore it down to the bare block. On a 460, the right bank of cylinders is numbered 1,2,3,4 and the let bank is 5,6,7,8. Well, the pistons and rods were installed 1,3,5,7 on the right and 2,4,6,8 on the left, meaning that 2,4,5 and 7 were in the block with the arrow on the cylinder pointing backwards. I don't see any signs of damage anywhere, no broken skirts, no unusual wear marks, etc. I'm going to put it all back together correctly with the correct pistons in the correct cylinders.... Is there any chance that this could have been the source of my noise? I can't find ANYTHING else abnormal or broken, and everything is brand new. Is there anything else I should check? I really don't want to have to pull this thing out of my car again.
were the rods installed backwards relative to the crank on some of them? the bearing is offset towards the center on many V8s, could be the edge of the bearing was hitting the fillet on the journal? you may know this already but the reason pistons are marked "front" is because the pin is offset to one side about .060" to prevent making that noise you're talking about
The pistons are on the rods the correct way, and the rods on the crank the right way too. The rods only go on the crank one way...numbers out. to get numbers out on 2,4,5, and 7, they were put in with the arrow pointing towards the back of the block. I didn't know the piston was offset. I suppose that could be why I was getting the noise. Where would that noise come from though? Is the piston skirt hitting the rod? Skirt slapping the cylinder wall? Everything looks perfectly fine, no abnormal wear anywhere....
just for fun, google piston pin offset and read up! also note that many racing pistons (and forged street pistons) have no pin offset.
If the pistons were in backwards wouldnt the valve reliefs in the pistons be also? You had no shiny spots around the reliefs or the ends of the valves ? Those Thats a BIG intake valve trying to fit in a exhaust relief. If Your running a forged piston with say 4 to 6 thou clearance the offset Sqirrel is talkin about could make noise in the bore I would think. More careful inspection should reveal the knock. GOOD LUCK ---FEDER
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