Hi, had what sounded like a knock just before putting away for winter,changed the oil to tranny fluid, let run a bit, changed back to oil,
put car away.
first start of spring, was revving high(carb adjustment) but noise was there.
warmed up, noise gone, had out a couple of drives, noise gone.

something I can trust now?
133000 miles, have owned for 35 yrs, only minor engine work.
69 442 400ci

 

I'd certainly consider a new timing chain with that mileage. Maybe do a compression test to make sure all is well internally.

 

Winter? Siberia, Australia, Tierra del Fuego, Bismark, ND? How long is winter? 7 weeks or 8 months? If it sat 8 months below freezing you had some serious sludge to get moving to the top.
Before I'd elect performing surgery on a timing chain or a compression check (at this point), you stated "....warmed up, noise gone, had out a couple of drives, noise gone." Unless I'm missing something, I'm guessing the noise is gone. Neither do we all equate what "...sounded like a knock..." to a knock; nor do we all equate what one person considers a knock to another persons consideration of a knock. If the noise is gone, drive it. If the noise comes back consider re-posting. Way too many variables here to consider any one item to be the issue. Don't commit to surgery until you have a real issue. If it sat for 8 months and all the oil was sitting in the oil pan, I doubt I'd have been "...revving high..." to begin with. I'd have started it, let it run one minute, turned it off, started it again, let run one minute, turned it off, started ran another 5 minutes kicked it down so there was no choke and let it idle for 10 minutes. You didn't have much oil up top and perhaps you're good to go. Noise gone - drive it. Fingers crossed.

 

I have had a rod eat the crank out without spinning the bearing and it only knocked over 2500 RPM.
I have had a transmission work loose, all the bellhousing bolts backed out a bit, that sounded like a rod knock.
I have had a broken rocker bridge that sounded like a rod knock.
Some of the new Dodge Ram trucks we have at work develop exhaust leaks that sound like a knock.
I have had a throw-out bearing go bad that sounded and felt like a rod knock.
I have had a stuck lifter that sounded like a bad knock.
I had a wheel come loose while driving that knocked terribly but it also shook the car. That was an easy one to find and fix.
Only a couple of the above were on the same vehicle. It may simply be a dirty lifter and changing the oil fixed the issue. It could even have been a loose air cleaner lid! Start by giving everything a once over making sure everything is tight! Use a dowel rod or engine stethoscope to try and find where exactly the noise is coming from. Any moving part of a vehicle can make a knocking sound if it gets loose enough. Even a v-belt can make a knocking sound if it has a gap on the inner part where it rides in the pulleys. Make sure you know what is causing the noise before you start taking things apart!