OK, this continues to drive me crazy, need your ears, it won't be easy

[My427stang]

Let me start by saying that I can't hear it - maybe you should stop by Mack and give me a ride.  I do have a quick and easy guess at it though. How about the speedo cable? It should be easy enough to take it loose down below and go around the block.  Later, Travis.

I should have you put an ear on it, at least there would be someone else who heard it.

Maybe one of these days I will swing by if pulling a wire doesn't ID a noisy hole.

[FErocious]

My 445 has a noise, and has had a noise for a long time.  It won't blow up, it's been apart twice since the original build for the noise, and I have found nothing.  The only thing I haven't done is Zyglo the pistons.  Heads magged, multiple cams, multiple rocker sets, multiple valve covers, clearanced the timing chain, multiple fuel pumps, nothing hitting down below, with or without PS, even reblocked to have tighter clearances because I originally built it loose, new balancer, clutch, flywheel, you name it. 

In the video below starting at 25 seconds, you hear a tapping that sounds like a loose valve, it's much worse when cold.  After all of this, my hunch is I have a bad piston, but I did not see anything on multiple inspections and it is silent at idle.

First request, listed to the video until you hear the minor tapping between 25 and 30 second point. Many people say they can't hear it, and it is tough, but once you tune into it, it sounds like valvetrain, although everything has been gone through multiple times.

After you hear it, generate ideas.  FWIW, I have been in pure parts replacement mode for over a year, the absolute only engine I have ever been in this situation.  The only things not magged or replaced are the pistons and rods, but my eyeball couldn't see or measure anything.  The crank was magged and checked.  All new parts,and it has made the noise since the original build without change

Thoughts, prayers?    Been doing this a long time and haven't ever ran into one like this.

About ready to put the spare 390, or maybe buy an LS off Craigslist LOL

https://youtu.be/VlHIl9hafYA

  Ross, it sounds like a collapsed piston skirt to me. I suggest a process of elimination to narrow the diagnosis down to the offending cylinder. Pulling a plug wire one at a time is a good way, as has been suggested.
  A second possibility is that a piston crown is tagging the combustion chamber .

[My427stang]

Thanks everyone.  Piston skirts all measured the same lat time I put it together, even marked crosshairs on every piston to make sure I measured exactly to make sure I didn't miss a thou due to being in a slightly different location, but I did not look more than an a good eyeball for cracks because of that and the bores showing no odd wear.  Additionally, I have never pulled the rings off the piston, so it is possible I missed something.

I think Doug's on track with his Sherlock Holmes statement.  I am not sure there is a more methodical person than me, and this is years in the troubleshooting. Block is square decked, precisely at .055 quench, D-cup pistons, nothing hitting above or below the piston. 

It almost HAS to be a bad piston, the issue is, it doesn't really sound like it to me LOL  it sounds like valvetrain, but the fact it gets quieter with engine temp (and the fact that every valve train component has been replaced, measured, or magged) leads me back toward a piston on the compression stroke.

I may jump on it today for a bit, at least to see if pulling a plug wire makes it quiet.  Didn't realize how burned out I was on it, but driving the Mustang for a nice 100 mile trip, to include a coffee cruise was good therapy

[TomP]

On the 428 in my ramp truck I had a weird buzzing and rapid tapping noise that drove me nuts for a month. It would do it part throttle around 2300 to 2600rpm. It wouldn't do it at that RPM unloaded or heavily throttle.
 Turned out to be the long header tubes that ran side by side. A hose clamp solved it, but only after the engine came apart twice and nothing was wrong.

[plovett]

If you find out that your speedometer cable is making this noise, I am personally going to drive up there and give you a wedgie. 

sincerely,

paulie

[My427stang]

If you find out that your speedometer cable is making this noise, I am personally going to drive up there and give you a wedgie. 

sincerely,

paulie

If it's a speodometer cable, it's wrapped around the crankshaft and hitting the pan   I wish it was something so easy.  However, where I am now, I will happily unscrew it and take it for a ride.

[plovett]

If you find out that your speedometer cable is making this noise, I am personally going to drive up there and give you a wedgie. 

sincerely,

paulie

If it's a speodometer cable, it's wrapped around the crankshaft and hitting the pan   I wish it was something so easy.  However, where I am now, I will happily unscrew it and take it for a ride.

I don't think it's your speedometer cable, either.  Just giving you a hard time.   

I would seriously be happy to ride in your engine bay with the hood off, if that would help.  I trust you to not go over 100 with me in that position. 

paulie

[fryedaddy]

i had my oil dipstick go to the wrong place onetime,it made a pecking noise till i straightened it up i thought i would mention this,you never know,it happened to me

[KMcCullah]

Have you tried a different viscosity oil? My 416 makes all kinds of piston noise with 15w40 Rotella. My home-boy hone job is the culprit here, I think. Seems to be getting worse with miles. I'm up to 2500mi now. But I can run 60wt VR1 and it quiets the noise a lot. Might be fun to experiment, Ross.

I also like TomP's rattly header tube hypothesis..... bundle em up with a big hose clamp and see what happens....

[Lenz]

I've listened to the audio and read this thread thru, thought I could hear it but?.  At one point you documented that you verified no exhaust leaks, so this may be old ground and way over-simplifying but could there be a minute crack in a header tube or where they are welded to the flanges?  As it heated up it would tend to close and quiet down.  Also, a tiny flaw of this type would only manifest under load conditions. 

[My427stang]

i had my oil dipstick go to the wrong place onetime,it made a pecking noise till i straightened it up i thought i would mention this,you never know,it happened to me

I have a pan mounted dip stick in a 4x4, absolutely a possibility in a car, but not possible in the pan mounted rear sump

Have you tried a different viscosity oil? My 416 makes all kinds of piston noise with 15w40 Rotella. My home-boy hone job is the culprit here, I think. Seems to be getting worse with miles. I'm up to 2500mi now. But I can run 60wt VR1 and it quiets the noise a lot. Might be fun to experiment, Ross.

I also like TomP's rattly header tube hypothesis..... bundle em up with a big hose clamp and see what happens....

So, the noise scares me enough that I don't want to drive it cold, and I have ran 15w40 and 20w50 and a few shelf blends during the times it's been together, so my hunch is the tap I hear is not oil related.  Plus all the clearances are blueprinted like every other hot FE I build and been checked "thrice" with the build and reblock and rebuild LOL

As far as the header tube, I will look, but man, it really is a tapping that coincides with engine speed, but I will still look again at the possibility.  FYI, there is nothing loose on the truck, I am a bit of a rattle/squeak crazyman.

I've listened to the audio and read this thread thru, thought I could hear it but?.  At one point you documented that you verified no exhaust leaks, so this may be old ground and way over-simplifying but could there be a minute crack in a header tube or where they are welded to the flanges?  As it heated up it would tend to close and quiet down.  Also, a tiny flaw of this type would only manifest under load conditions.

So I have been all over the headers because it often seems logical as a possibility, but it just doesn't sound like that.  That being said, this last time I bolted them to a head, no rockers, and pressurized them with air, a whole bunch of nothin with a Windex bottle.  Additionally, they are ceramic coated headers that were quiet with the original 396.  It all goes back to "new stroker kit came with a new noise" 

I have to go out of town for a bit, but hopefully this weekend I can try pulling wires to see if the noise changes.  If it does, I would have a head off and a piston out in under 30 minutes

[country63sedan]

I just thru the speedo cable out there - I don't think we need to resort to wedgies.  I've chased noises on trucks and found some crazy results. It can be a real PITA figuring out what a noise "looks" like. Did you remove pistons from rods and check rod bushings? I sure hope pulling plug wires narrows it down. Later, Travis.

[jayb]

I had a serious intermittent knock in my Mach 1 once.  Turned out that one of the header tubes was tapping against the front subframe at certain times.  I assume you've ruled out something like that...

[fryedaddy]

you could also add that at different rpms your engine will move around more or shake more or less

[Barry_R]

After years of chasing it is almost worth it to pull the thing and stick it on a dyno so you can stand next to it and put your head against the valve covers or oil pan.  I've had some really crazy stuff make noises - windage trays and the flat tin under an intake will amplify the smallest contact and make it sound horrific.  I've had rockers touch an otherwise well clearanced valve cover in one spot, I've had one rod bolt touch a tray, I've had a single broken inner valve spring, I've had the dipstick wrap up, I've had a fuel pump with a broken return spring, I've had a roller lifter tie bar hitting the block, I've had worn rockers clip on a valve tip - - seems like I've found every one of them only after eliminating a million other items....