[STEELCITYFIREBIRD]

I can't tell anything from video.

I'd firstly remove belts and see if you still hear what your looking for, that will rule out any accessory,water flow possibilities.

On the exhaust end, plug up the tail pipe/s and see if it builds pressure, listen for air leaks. Will have to do both @ once if duals with cross over or intake heat crossover is not blocked off.

[NeighborsComplaint]

Strong possibility is the water pump bearing going out. Pull the belts and see if the noise goes away.

How is your oil pressure? You will see bearing particulate when you spin a rod bearing. Last time I heard that sound I had spun a rod bearing. No knocking, just a "chuffing sound" when the motor was running and at low rpm it felt like something was pulling the rpm down. I had no oil pressure gauge at that time or I would have noticed an oil pressure drop.

Does it backfire on starting (valve lash too tight)? Immediately after you shut it off do you hear a hissing sound under the hood (tight lash and/or guides). If it is guides, the motor would smoke on cold startup and smoke on deceleration (oil siphons past the intake guides.

[67gtospud]

Is it possible there is air in your heater core and the coolant is splashing around in there?

[JLMounce]

Originally Posted by STEELCITYFIREBIRD

I can't tell anything from video.

I'd firstly remove belts and see if you still hear what your looking for, that will rule out any accessory,water flow possibilities.

On the exhaust end, plug up the tail pipe/s and see if it builds pressure, listen for air leaks. Will have to do both @ once if duals with cross over or intake heat crossover is not blocked off.

I'll check this out.

Originally Posted by NeighborsComplaint

Strong possibility is the water pump bearing going out. Pull the belts and see if the noise goes away.

How is your oil pressure? You will see bearing particulate when you spin a rod bearing. Last time I heard that sound I had spun a rod bearing. No knocking, just a "chuffing sound" when the motor was running and at low rpm it felt like something was pulling the rpm down. I had no oil pressure gauge at that time or I would have noticed an oil pressure drop.

Does it backfire on starting (valve lash too tight)? Immediately after you shut it off do you hear a hissing sound under the hood (tight lash and/or guides). If it is guides, the motor would smoke on cold startup and smoke on deceleration (oil siphons past the intake guides.

I'll check this as well. Oil pressure while driving is between 40-60 psi depending on rpm. It's a little lower than I'd like at idle. Around 10psi at 650 rpm. It rises to above 20psi at 1000 rpm.

No backfires when starting and no hissing when the engine is turned off. No smoke under any driving condition. My vacuum gauge does bounce wildly which I have read is an indication of a valve guide issue.

Originally Posted by 67gtospud

Is it possible there is air in your heater core and the coolant is splashing around in there?

There's always this type of possibility. I'd like to flush the coolant anyway, so I'll burp the whole system while I do that.

One thing I was going to run by everyone is if the mechanical pump is vaporlocking, would that cause this type of noise. I've noticed with the heat up, that I'm getting what appears to be vaporlock. Percolating fuel, intermittent pressure drops from the pump. I can also hear the fuel boiling in the floats after shutoff. It has stalled on me once as a result.

Just ordered a phenalic spacer, new soft lines for the engine compartment , heat shields for the lines and new intake gaskets with exhaust cross-over blocks.

[GOLDOHC]

Sounds like a friends car, that didn't have a engine breather on a valve cover.

[JLMounce]

Originally Posted by GOLDOHC

Sounds like a friends car, that didn't have a engine breather on a valve cover.

Interesting you say that. This engine has a set of Holley valve covers on it. Passenger side has a breather, driver's side does not.

[mchell]

does the engine pull hard throughout the entire RPM range?...sound like you have an obstruction in your exhaust system ...or as others have said, massive exhaust or vacuum leaks

[Jim Scites]

If you have power brakes pull the vacuum plug out of the power brakes or pull the hose off and put your thumb over it to see if the idle changes. Do the same thing with the pcv valve, pull it out of the valley pan and put your thumb over the end of it to see if the idle changes. If either of these things change the idle, repair accordingly. I hope it's the pcv valve because they are the easiest to change.

[JLMounce]

Originally Posted by mchell

does the engine pull hard throughout the entire RPM range?...sound like you have an obstruction in your exhaust system ...or as others have said, massive exhaust or vacuum leaks

Yes, once I put some timing in it and filled it with the appropriate octane, it pulls hard to 5500 rpm.

Originally Posted by Jim Scites

If you have power brakes pull the vacuum plug out of the power brakes or pull the hose off and put your thumb over it to see if the idle changes. Do the same thing with the pcv valve, pull it out of the valley pan and put your thumb over the end of it to see if the idle changes. If either of these things change the idle, repair accordingly. I hope it's the pcv valve because they are the easiest to change.

I'll check this, thanks for the tip.