Need 440 advice! Strange intermittent knock

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vracing80Z

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Hoping someone can shed some light on this one... Got a new my newly rebuilt 440 running... 30 over, forged pistons, solid roller, ported stealth heads, RPM intake, Demon carb, high volumn pump and Harland sharps. When I first fired up the motor, it ran fine with no strange noises. I shut it off and hooked up the timing light and vac gauge to tune and started hearing a strange knocking sound like a bearing. I shut it off and started lookin for anything hanging and so on. Found nothing. I was pissed and walked away for a day or two. I went back to restart the car and show "the throttle stop" (My wife) the car was dead and I wasn't kidding. I fired it up and there was no knock?? After running for a few minutes, the knock came back and would disappear while running?? There are times that it doesn't knock at all. Anyway, I changed the oil and had a flashlight beaming through the draining oil to see if I could see anything shiney. Nothing. I checked the magnetic milidon plug and it had nothing abnormal from a fresh engine. No flakes of anything. Like I said, the noise is intermittent. After I changed the oil and started the car, it knock pretty good and then it was like the oil circulated and it was quite again. I did check the converter bolts. When the car is knocking, if I hit the accelerator, the noise goes away, which would lead me to believe it is oil related. HELP!!!!:banghead:
 
Ok start it up again when its knocking pull a plug wire off one at a time to see if its a bearing,wrist pin,or piston slap.Good luck I am sure the real knowledgeable guysssss will chime in here.
 
It has 70 psi at 1000 rpms. The knock is intermittent and goes away with no warning. It could stop before pulling a plug. It does it for a few seconds while running and magically disappears?? I had about 32 degrees advance total to start out with. I now have 36 total. It runs better at 36. Doesn't seem to affect when the knock kicks in.
 
Sounds like it could be the thrust bearing. Take a largescrew driver or small pry bar, and see how far you can move the crank in and out. How much piston to wall clearance did you have?
 
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