Eng Noise, help

[tooslow]

I have 440 and I recently noticed an engine noise at idle, 800 RPM. Sounds Like a small hammer is bouncing around inside. Noise disappears as the RPM's are increased
1). The sound has no apparent frequency unlike a rod Knock. At first I thought it was a broken motor mount or the exhaust manifold hitting somewhere.
2). As I increase the RPM the noise disappears
3) My oil pressure drops to 30 psi at 800 RPM and i hear the noise . When I increase the RPM the oil pressure goes to 70 psi. No noise
4) My oil pressure used to never drop below 50psi at idle, 800 rpm, now 30 psi

Should I pull the motor and open it up?
446 CI
mechanical Cam Dur @.050 = 260 and 558 lift
10-1 CR w AL heads

 

[fnaramore]

Do you still have stock manifolds? Sounds exactly like an issue I had. Heat riser broke and would rattle at idle and go away once the rpms went up.

 

[tooslow]

EXACT SYMPTOMS

446 CI
Mechanical cam @.050 256 duration 558 lift

My oil pressure is always around 70 psi from idle to 5500RPM, fluctuates 5 PSI the whole range-NO NOISE

Sometimes when I idle my pressure drops to 30 psi and I hear the erratic hammer noise coming from the center of the engine.
Right now the car is idling at 800 RPM 70 psi no noise
WHY it suddenly dropped to 30 psi at idle then returned to 70 psi at idle I do not know?????

I have header . Not a heat riser rattle . the noise is a heavier hammering. Just like a heavier hammer head was bouncing around but only at 30 psi

 

[fnaramore]

Provided oil is nice and clean, guess would be the oil pump is dropping pressure because its going bad or it's not being spun. Personally, I'd break open the motor, I just prefer to see what's going on. If you want to poke around it a bit more first though, you can take the belts off to get less noise and listen in. My personal guess is when the oil drops the lifters are getting a little sticky. Sorry I couldn't be much more help.

 

[TrailBeast]

A loose rod bearing coupled with a sticking oil pump pressure spring will do that.

 

[tooslow]

I was smoking crack the engine always idles at 30 psi when warm, The hammering disappeared. I took it to 5500rpm and 162 mph and the hammering sound is gone. Gunna pull the heads and pan anyway. Check my crank endplay, plus moving to a mech roller cam
thank you