[bluejudge]

Originally Posted by pngoat

Check the big balancer hub bolt for looseness. Should be 160 lb. ft. Next check the bolts that hold the balancer itself and the pulley to the hub. Should be 25 lb. ft. Also check the power steering (if equipped) pulley. Should be 70 lb. ft.

Yes, check on this suggestion. It cost you nothing to check. I had the same kind of noise in the front of my motor. Sounded like a bearing noise, or as I put it, marbles in a can making noise. I took the valve covers off and checked the rockers and it was not that. So I changed the water pump because it sounded like a bearing noise, it wasn’t that. Then I went to check the balancer, and it was the four bolts holding the pulley’s on. The bolts were almost sheared off. I was lucky to catch it before everything in the front of the motor let loose. Good luck…

[chiphead]

It's a '69 400 with the 11 bolt water pump and the later balancer.

Here's the results of today's testing:

Similar noise with both belts removed
Some belt and fan noise went away, making the rattling sound easier to hear. It sounds like sheetmetal contact/rattling/tapping near the center or front of engine.
All rocker arms adjusted and all pushrods spinning
Balancer is a nice SFI piece, not slipped or coming apart
Bottom pulley bolts are tight. RARE billet aluminum bottom pulley
I need to check balancer bolt with a socket, but the balancer didn't have any slack when I pushed/pulled on it.

On start, It doesn't make the noise for the first 15-30 seconds, then the noise starts. I stopped/started the engine 3 times, and there is a slight delay between engine start and the onset of the noise. Can hear it topside, loudest near the front. Can't hear it under the car, at least not over the exhaust. It almost sounds like the exhaust hitting something, that sort of rattley tink tink noise. But coming from inside the engine.

I pulled the fuel pump and used an inspection camera to get a few pics of the fuel pump eccentric. I used a screwdriver to move the outer ring to the front. It seems to have about .100 or so of forward/backward slack on the inner eccentric. The outer ring will sit flush against the gear or move forward as the pics show. Sorry for the weird angle, its hard to get in there and take pics.
Is this normal? I got a video too, but will have to upload it to YT later.

[mgarblik]

Well your eliminating some sources of the noise, so that is good. You could start and run it without a fuel pump and see if the noise changes. (sounds different, goes away or gets louder). That might help you zoom in on the fuel pump drive. if you don't have one, you could make a fuel pump cover out of cardboard for this test. Shouldn't make too much of a mess in 30 seconds. Any way to check if the thrust plate bolts have backed out and are contacting the camshaft sprocket? Not sure if you can see well enough in there. Also, is this a manual or auto trans car?

[Squidward]

Originally Posted by mgarblik

Well your eliminating some sources of the noise, so that is good. You could start and run it without a fuel pump and see if the noise changes. (sounds different, goes away or gets louder). That might help you zoom in on the fuel pump drive. if you don't have one, you could make a fuel pump cover out of cardboard for this test. Shouldn't make too much of a mess in 30 seconds.

Personally, I'm a duct tape guy. Lol.

Good mention about cam thrust plate.