Re: Engine Knock (Me too!)
All good advice here.
What you will be trying to do is isolate where the noise is coming from, and exactly what type of noise it is. Think of it like one of those AAMCO commercials (if they air where you are) where the people are making all kinds of funny noises, and the AAMCO expert knows exactly what it is just by the noise.
A lifter makes a different noise than a slapping piston, an exhaust leak sounds different than a bent pushrod, and so on.
I would not advise a novice to try and set/change valve (actually rocker arm or pushrod) settings without a whole lot of direction. If you end up tightening something that didn't need it, you can apply too much force to the cam and round off a lobe. If that is what it turns out to be, we can direct you to appropriate procedures (providing you can tell us what kind of cam and valvetrain you have: roller cam, solid or hydraulic lifters, OE type stamped steel rocker arms vs adjustable and/or roller tipped, etc). If possibly having to "adjust the valves" after some cam wear was mentioned, then you probably have something other than a traditional hydraulic lifter "flat tappet" cam; when set up correctly after assembly and checked after break in, those are normally a set and forget style of cam and valvetrain.
One thing I did not see in the advice above is trying to isolate a cylinder if indeed it is an engine noise. Once you have it up to temp, or whenever the noise is occurring, you can disconnect spark plug leads one at a time to see if the noise is only associated with one cylinder.
Make sure you check simple things, like making sure none of the spark plug boots have burned through because of contact with the header. I mention this because I chased a noise and a miss all over on my 68, despite all my so called "knowledge" and working on engines since before I was a teen. I returned two "defective" Edelbrock QuadraJets (boy, do I wish I had those carbs now), and did a bunch of other things before, going to remove the plugs and check condition, I found one of the MSD plug boots had burned through on #1 or #2. I was so smart, I knew the issue was carb or timing/distributor related... until I found such a simple thing.
And always mark things like the plug wires (and distributor cap, if you remove that end too), because we have seen too many guys try to diagnose something like a small noise and come back that now their car won't run at all, because they put something back together incorrectly. I've done it, probably most folks here have some similar "boy am I dumb" moment. You'll have yours too. Just try to minimize...
69 'vert project big block/TKO 600 RR
68 'vert driver RS clone -- gone!