https://youtu.be/TGr-bMuy8eY

Here is a small clip. If you listen carefully you can hear what I can only describe as a raspy rattle when the engine hits about 3000rpm. It's louder the harder you accelerate. You do not hear it below or over about 3000rpm. It does not sound like engine tin rattling or the engine lid. Sounds internal. This being my first type 4 motor I'm not familiar with common sounds it might make. Can it be valves or guides? Anyone hear this before?

Thanks. Scott

A bit hard to tell but it sound like piston contact,when were the valves last adjusted ? I would also check over the rocker gear.

maybe a video of the car running at 3K parked? But with all the shifting in that video, I would think it might be exhaust related. There is lots of tin on these cars, if you are missing a few screws it can vibrate pretty good too.

I had a scary sounding clank a few years back and it was the alt pulley. Lots of video listeners, along with me thought it was a rod clank. Luckily it was the ALT shaft moving in and out. A direction it is not supposed to go.

I had planned to run the car for a bit with the ALT belt off to see if the noise went away. When I grabbed the pulley it moved laterally, the end.

My first guess is rod knock.
But it could be:
detonation - have you changed the timing lately or was the engine running really hot?
exhaust leak - has a knock-type noise with associated "pfffft", but cant tell from video
loose engine tin - but this sounds "heavier" than a tin.

If you ever suspect bearings going bad, the first place to look is to take the valve covers off and look for metal flakes.
That is quicker/easier than draining the oil, but if you are due for a change?

Thanks for the input guys. This noise has been there since I purchased the car. When I got it, it had a very bad exhaust leak. The collector near the mufflers was badly cracked. I welded that and the leak was better but not all the way gone. Come to find out the car was missing all the copper exhaust gaskets! Replaced those and the gaskets where the mufflers mount to the heat exchangers. Exhaust leaks gone. Now I could really hear this noise I'm talking about. When I adjusted the valves I adjusted them slightly loose rather than tight. Did not affect this noise. The noise seemed to go away a bit the more I drove the car. Or at least I thought. I just have header pipes and none of the heating parts. So I had hot air escaping from the fan housing. When this was happening I noticed the car getting hot after about a 20 Minuit drive on the freeway. I've since blocked those holes and it seems to run cooler now. As far as recording it sitting in neutral? I'm not sure it will make that noise. It seems to happen more under a load. I will try that though. Does any of this info change anyone's ideas?

I changed the oil and I did not notice any shavings. But the oil looked fresh when I got it. So who knows if there were any at that change. I have a feeling this car sat for awhile before I got it. Unfortunately I bought it from a dealer and don't have much info. They brought it from Arizona. Hope it's not rod bearings. I believe the engine to be original to the car as well as the trans. Looks like the car has 83,000 miles on it and the motor looks like someone split the case in the past as there is red RTv sealant at some of the case bolts. Heads look a lot cleaner as far as oil and grime compared to the case. Maybe that's normal. I also have reason to believe the motor might have been upgraded to a 1.8 because of an old advertisement of this car someone saw a couple of years ago. They entered the VIN here when they saw it for sale and mentioned a few details of the ad. Not sure how to tell wether it's a 1.7 or 1.8. Case says it's a 1.7

Engine does not make that noise when sitting at neutral. Only under a load it seems. The noise is most noticeable in the video near the end on my last acceleration.

Could it be tranny or axle related? Seems like when you add them to the mix you get the noise. Chipped tooth in tranny or bad CV joint or rear wheel bearing maybe? I had loose flywheel bolts make a rod knock noise but it did it in neutral or in gear under a load. One of my cars made an ugly noise because of bad rear bearings

Appreciate the input! I don't think it's bearing noise. And I'd be shocked if it was the tranny. I do think I have to do the rear bearings though. But this noise is from the engine. The more I think about it makes me remember a few things. When I first installed the dual carbs. A friend and I were tuning them. I did notice this noise then when Erving it up. It was noticeable as soon as you gave it a bit of throttle. But like I said earlier. The noise seems to have gotten better. I don't think I hear it as much off throttle anymore when in neutral. Maybe a little when cold. Goes away or is less when warmed up. Except as seen in the video.

You probably won't see much in the oil itself, you have to cut open the oil filter. That's where the loose metal ends up.

So you thinking rod bearing?

There's no way I can tell from the video.

Is your oil light coming on or flickering at idle?

IMHO you have a few options; tear it down before it gets any worse, wait until it breaks then tear it down, or start looking for a good replacement engine.

No, engine oil light does not flicker at idle. It did at one time before I got my carbs dialed in. But the engine was hot and the idle was very low. Maybe 500rpm. Since I've got the carbs running well and seemed to have solved my cooling problem I have never seen it come back. I understand. Very hard to tell from a video. I guess time will tell. If it gets worse I'll pull it and tear it down. For now its running pretty well and I'mm just going to drive the hell out of it.