Knocking (Rod knock?)

Hello, I have a knocking problem that I cannot figure out. I don't know if it is rod knock, but I will explain everything in a few paragraphs. I hope somebody with a lot of knowledge will take the time to read it all and try and help me out.

I have a 1995 Chevy Lumina with a 3.1L Vee 6 engine. I don't know a lot about cars, but what happened was, I bought a 2003 silverado, so i was going to sell the Lumina. I was driving the lumina to school and the head gasket went. I got laid off 2 days after I bought the truck, so I didn't have the money to pay to have the top end rebuilt, so I took on the venture myself.

I had a chiltons by my side, and talked with my girlfriends step-dad (who lives 60 miles away) and took on the enormous task (well... enormous to somebody who never even changed their own oil)... I read a lot online, read stuff at howstuffworks.com, and a lot of other websites. I rebuilt the engine myself, I used Anti-sieze on the bolts, used copper sealer on the head gaskets, had the heads finished, used RTV in the joints where i was afraid the gaskets might leak. I did everything I was supposed to. When I got it back together it wouldn't start. I tried everything, talked to a lot of people (my uncle, who is a couple thousand miles away) and couldn't figure anything out, other than speculation.

I had it towed to the local dealership and they said the computer was bad, so $500 later (keep in mind, i had no job, and a silverado payment) my car ran, but it know has a knocking sound that the dealership told me was probably rod knock. I didn't have the rocker arms/valves torqued properly, so I was just hoping that it was just the rocker arms making the noise. I got it home, and torqued the rocker arms down like my chiltons told me, and I still get a knocking. I have talked to my g/f's step-father again, and he says that he doubts it is rod knock because I didn't drive it but maybe 100 feet after the head gasket blew because the engine died. It didn't get hot enough for the rod to expand. Because the dealership said they thought it was rod knock, I had the rod bearings replaced (i don't have an engine lift, or know anything about the bottom end) (also, about the rod bearing fix, i know, it is known as only a temp fix, but i just wanted to sell the car because i was out of work). It didn't make ANY difference, this is another reason my g/f's step dad doesn't think it's rod knock.

It's too loud to be the water pump, I don't know what it is. I tore the valve covers off again to make SURE all the pushrods are properly seated in the lifters and that all the rocker arms are torqued properly, and they ARE. It still makes the noise.

I will try to describe the sound as well as i can in words. It knocks with every spark of one of the cylinders, and it will go away for 10-20 seconds every minute or so (which is even ANOTHER reason my g/f's step dad doesn't think it is rod knock). I don't know what else it could be. I don't know enough about engines to know if it is pre-ignition/detonation, or anything like that. I just know it doesn't sound good. I want to know if there's any way I can tell if it's a bad lifter, or anything else that might be easier to fix, without rebuilding the bottom (i don't have an engine lift, nor the money/time to rent one (btw, i'm working again trying to pay off the debt i built up while laid off))

Does anybody know if rod knock is something that would kind of come and go.

Also, if anybody's still here, one last symptom: the knock seems to be worse after the engine warms up.

Use a long screwdriver with a plastic handle to push against various surfaces on the engine with it running (including the distributor cap). Put the metal end against the engine parts, hold the plastic part. If you feel a tapping vibration that is particularly strong at one location or another, chances are you've found the neighborhood that your culprit lives in. If you can't feel any tapping vibrations anywhere on an external surface, then put your ear up against the plastic handle while holding the other end against a valve cover, side of the block, etc. Keep listening around until you find the area that your noise comes from.

sometimes a distributor will start to make a clacking sound if the drive gear or bearings are worn.

Check to see if the outer ring on the crank pulley (TV damper) is loose. That can make a rattling noise.

A blown head gasket could definitely damage engine bearings - coolant+oil slurpee isn't a very good lubricant.

try running 91 or 93 octaine