Quote from: NWwildman on August 23, 2016, 12:10:31 PM

The car will make a slight knock very quickly when it first fires after sitting for a while

This is the key statement. A bad main bearing will typically make a noise when first started, then quickly go away as oil pressure reaches it. It could still be a rod though. You're not doing it any favors by running it at WOT, trying to figure out the problem. If you can't find any external issues, then it's time to start tearing into it and find the problem...before something worse happens.

I realize the potential danger of WOT runs if there is a real issue at hand.  I have only done a couple in an effort to narrow down the rpm range/cause of the issue.  It does have a tiny knock on startup when warm that lasts just long enough to be audible then clears up.  I guess my quick fix used 390 will be anything but.. looking more and more like I need to halt my other projects and finish the engine I was already building for the car.  That said, I'm going to investigate the flexplate today or tomorrow.

You re-torqued the manifolds and changed the donuts and it went away.  I would highly recommend looking at your manifold the head gasket situation.  If when you re-torqued it went away a compromised gasket may have been temporarily silenced.  A heat and cool cycle or two would open up a bad gasket fairly quickly, and other than the donuts that is the only variable you messed with to get the "knock" to go away.

I have thoroughly investigated the exhaust and can't seem to find any leaks, I am not ruling it out but this knock is pretty intense when it does come on... Though JayB and some others have mentioned exhaust leaks being convincing as knocks.  Man this is frustrating.  It runs so darn good, I can't picture it being a wrist pin or rod bearing but on the other hand I just can't seem to narrow it down.  Starting to think I'm gonna have to get my wife to drive it while I ride on the fender like Stroker Ace with the stethoscope to find this damn knock.

It's BACK!

So here is the exact circumstances where the noise is present.

Oil pressure stats:

cold 600 rpm 75-80 PSI
Cold rev 2000 rpm 75-80 PSI

Warm/hot idle 25 PSI
Warm/hot cruise/rev 45-60 PSI

The car will make a slight knock very quickly when it first fires after sitting for a while

The engine is silent when cold and oil pressure is high, revving, idling etc.

Once the engine is warm it knocks like wild when revved beyond 2000 rpm and rattles as it slows down then gets quiet once it hits idle speed.

Engine is whisper quiet at cruising speeds (so quiet that you'd think it died) but if you hammer on it and wind it up it will knock like mad at higher RPM but never loses power.

The engine does NOT smoke, burn oil or misbehave any other way.  There is some blowby that is consistent warm or cold.

Then engine runs strong and can get rubber from a stop (good for a bone-stocker) but the noise is bad and I know something is angry in the engine... Tried a stethoscope but cannot narrow it down to a certain area very well, tried a broom handle as well but no luck.

Could this be valve springs causing all the commotion?  I know that they were rather weak when I had the engine on the stand but since it keeps pulling at higher RPM is just doesn't feel like valve float but ??    Stumped!

So I'm working out the bugs on my '64 Galaxie 390/C6 and since I re-installed the engine I am having issues with the shift linkage z-bar/rod slipping out of the bracket on the back of the block.  I can shift it all through the gears like butter until I drive it and then it pushes the rod out of the hole and I have no gear selection capabilities... I can see the issue but I'm not sure if someone messed around with it previously and if I may be missing parts.. does anyone have a diagram for what parts are supposed to be on a column shift car? 

Many thanks in advance!

Jayb, I will do a little more poking around and report back.  I moved all of the rods around for side clearance when I had it apart to do the oil pump and gaskets and everything checked out good, also no particles in the pan and the pan was quite clean when I had it off.  I'll get out the stethoscope and see if I can narrow it down better. 

So here is a quick rundown of the engine history/story:
70's 390 4-barrel, older engine that I bought used.  I installed all new gaskets, timing chain/gears, intake, HV oil pump, etc.
Engine has good compression on all cylinders
80lbs oil pressure when cold, 40-60 when warm.

Dropped it into my 64 Galaxie and it fired right up, took for a shakedown run and it runs out nice, idles relatively smooth and cranks right up.

THE NOISE:  Never heard the noise until days after install when I was monkeying with the carburetor linkage... This doesn't sound like a top-end noise to me, I have heard numerous lifter taps, flat lifters etc in FE's and this doesn't sound like that to me.

The noise is a definite knocking sound, BUT it only seems to come on at aaround 2000 RPM when I'm free revving the engine and goes away at idle and goes away at higher RPM..  I'm stumped

I moved the timing around and it doesn't seem to have any effect at all.  The engine runs good, has a little blow-by but nothing crazy. 

Wrist pin comes to mind... but wouldn't a wrist pin be more persistent ??