Rod knock?

If you know the engine rebuilder, consult with them. If you don't know then pull the engine and put it on an engine stand. Filter the oil through a milk filter (available at places that sell agriculture feed). See if a magnet picks up the particles. If not then likely babbett.

Take the pan off, take out the pistons and rods. Take the rods to someone who can check that they are straight. Take the main caps off and check the clearance. Move the crank back and forth to check for end (thrust) clearance. Check to see if the cam gear is tight on the camshaft. There should be no perceptible fore and aft movement of the crankshaft. The rod bearings can move fore and aft without issue. Take the pressure plate and clutch disk off and remove the flywheel. Remove the flywheel housing. Remove the crank to inspect the bearing material in the block. Remember to mark the location of every bearing cap, piston, and rod using a punch or small pointed grinder. The marks are traditionally on the cam side. Keep track of the shims.

A knock on acceleration is usually a main bearing. A rod knock can be heard by running the engine up to a fast idle and then slowly backing off the throttle. Rod bearing can be ruined by having the ignition too advanced.

If the bearings are not bad (broken babbett) they can be taken up by removing shim stock.

Use an assembly lube when putting the engine back together. Keep everything super clean and change the oil after 50 to 100 miles.
 
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Engine rebuilding equipment needs to index from previously machined surfaces.

If the top of the cylinder block was resurfaced, it may no longer be parallel to the bottom surface of the cylinder block.

If the cylinders were bored perpendicular to the top surface, the connecting rods will have a fore/aft thrust loading.
 
Good point, Terry. The bare block can be put on a mill bed and dial indicator on the opposite surface to see if they are parallel. Or a large granite block can be used instead of the mill with the dial indicator mounted on a rigid arm. Checking to see if the bores are perpendicular is a little more complicated and will require some sophisticated measuring equipment. The quill on the mill might be able to be used with the dial indicator mounted on it and run up and down the cylinders. You can hire companies that will do 4 place measurements of your block.

I guess the simple test is to turn the engine over and see if the rod bearings move back and forth on the crankshaft. If everything is lined up straight they will not move fore and aft.
 
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Before I pulled that engine I'd pull the side cover off of the cam gear and check it.

Has anyone used a mechanics stethoscope to try to narrow down the location of the knock?
 
"Has anyone used a mechanics stethoscope?
Dave: No. The Rockford A's aren't quite that advanced.

Jim the owner will be taking the car back to the rebuilder, (who shall remain anonymous) tomorrow or next week and take the guy for a ride. Like Terry Burtz says something could be out of square with this engine.
Nkaminar: All good points.
Personally, I think that this engine will have to come back out for a thorough examination by someone who knows what they are doing. Stay tuned.
 
I'd tighten the rods untill you can just move them from side to side with a small hammer. I've done this many times without any problems.
 
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