knock at start up

Update so far, to answer Tom's questions, I bought this car last summer and I didn't have any knocking noise until now. Never over heated. I removed the fan belt and found a wobbly fan pulley....not the water pump shaft, just the pulley. To my way of thinking, if that was the knock it would do it all the time not just at start up. Now I notice I got an oil leak out the cotter key hole....not a bad leak but a leak. So my plan is to fix one thing at a time starting with the fan pulley...pulling the rad, head light bar etc. Then, the oil pan to see if that little tube is in place. hopefully I hope I don't find a broken Babbitt that's going to cost an arm and a leg. What I do know is I can't get to all this until next week.
 
It is most likely a bearing knock. Rod or main, but maybe not. With out hearing it it is hard to say. But with out figuring out where it is coming from it is going to be hard to find unless you are lucky. What if it is a bent or twisted rod. Are you going to check every part inside the engine. There are a lot of parts in side the engine.
I would try shorting out each cylinder. Have some one that knows model A's check it.
 
My money is on loose main bearings. When the engine sits for awhile the oil drains out of the valve area, which is where the mains get their oil from. After start-up that area is filled by the pump, and oils the mains. You could pull the distributor and pour a quart down the hole to pre-fill the valve area, start the engine as soon as you can. If the mains are the problem, the knock should not be heard.
 
Another up date. I thought I would try this before I get into dropping the oil pan and getting schooled on Babbitt bearings and shims etc. Castrol makes an oil called GTX Magnatec. There claim is up to 75% of engine wear occurs the first 20 minutes of warm up. When the engine stops ,oil drains off critical engine parts, but Magnatec doesn't, dramatically reducing engine wear. Again that's there claim. I'm not selling Castrol. I drained out Rotella 15W40 and put in the Magnatec...ran the engine up to operating tempature (160) for a while.....let it sit over night started it up this morning and to my surprise no more engine knock. I know I'll get razzed...snake oil....BS...all that stuff, but I wanted to pass along what worked for me. It's not cheap, I think I paid 7.19 a quart. At this point it's better than dragging my old tired arthritic body under the car again.
 
They have 5W 30 and 10W 30......I used the 10W 30. If you can find it in the 4 or 5 quart jugs you would save 5 bucks. The Advance Auto Parts I was in didn't have the 10W 30 in the jugs just the 5W 30, so I just bit the bullet and bought the 5 quarts to get the 10W 30.
 
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