Thoughts on knocking sound??
 

https://youtu.be/yWdNc6KGFZo

Well we have nice knocking type sound in our GP. It has about 300miles on it and 5 1/8 mile runs. Not sure when the knock developed but it was there before the racing occurred. I haven't had time to really look into it much but it's loudest on the driverside towards rear. Oil in top of head is clean, oil pressure is good, it doesn't seem to change from cold to warmed up.
My action plan when i get to car next weekend is change oil and cut filter, disconnect converter from flex plate, pull drive belts (so engine is isolated from everything). But I think it's coming from down inside :(.
Any thoughts?

I like the plan of an oil change and filter inside inspection. Before you isolate the engine from everything else, a quick check is to set the idle at about 1000 RPM. Use insulated pliers and pull up one plug wire at a time to disable it. Then move to the next one. If the noise goes away with wire out and comes back with it operating, you found the cylinder. If the noise stays, it's main bearings, or something outside the engine. (flex plate, accessories, torque converter).

1st thing I'd do is take valve cover off to see if everything looks OK.
Check that header gasket isn't blown out.


Then yank engine.


:(

Had valve cover off and things looked good, ran my finger through what oil was sitting there and oil there looked clean, rockers looked/felt normal.

Are the lush rods turning? Someone on here was having an issue w that on a new build sounds like your is fairly fresh. Is it hydraulic or solid lifter? Could be a wrist pin too. Doesn’t sound like a rod knock at all.

Hyd roller. Rockers and pushrods seemed to adjusted and good. But I do plan to look them over better next weekend. I had about 15min to look things over now. So didn't get too far.

Maybe a rocker hitting the bolt hole area on those M/T’s ?
I ‘ve had that happen before. It would be nice if it was that easy.
Take a pair of stock valve covers & try em.

Good luck!
Murf

I had to run a double cork gasket with some versions of the M/T Valve Covers to
have proper rocker arm clearance.

Tom V.

Make sure crank pulley isn't loose.

Dam that's too bad. Does sound like it's coming from internals to me. Ya run it without the torque converter connected first and like AG says check the balancer and crank pulley.

After you kill each cylinder with the yanking the plug deal if that proves fruitless, and if the cars auto trans then unbolt the converter and back it off the flexplate and see if that changes things.

An SD Rod can knock a dented oil pan, OR when sitting on an F-body crossmember.

Check crank pulley for ovel holes allowing slosh-knock. Itsa thing.

In your case the Roller Rocker Arm(s) is knocking the M/T cover bolt boss or ceiling. Pull em, inspect em, grind em, and use even thicker gaskets.

FWIW, I've run into that same type noise that sounds like valve train mis-adjustment that is actually loose valve guides. The valve being able to rock in the guide will sound like your noise does. I've found if you run the engine at idle and exert pressure on the spring retainer pushing it to the side the noise changes, and you can isolate which one/ones are making the noise.

I've also used a piece of vacuum hose running to my ear to isolate engine noises as to where they originate from. Of course the long screwdriver, or long socket extension can also be used, but I prefer the hose method to zero in on the origination of the noise.

Back in 77 when GM decided tp listen to bean counters, instead of the people that knew better, and made the iron alloy in the heads and blocks softer (less nickel) than it was previously, valve guides went out in GM cars quite often, especially SBCs. The first example I ran into was a 1977 Impala 305 with only 17,000 miles that had loose valve guides. GM continued to make the low nickel parts, losing them a huge market share to other manufacturers because of engine failures at low mileage due to soft cast iron alloy.

I also noticed from the video, that there seems to be a slight miss that coincides with the noise. Maybe hook a tach up, and see how much each cylinder drops when pulling plug wires. Loose guide could possibly cause one cylinder to be slightly weak due to the valve seating poorly.

Check your valve lash very carefully.

How’s your rocker arm to retainer clearance?

They're hyd, not much to check.

That's good, that was looked at when assembled

Check the Rocker Arm to Valve Cover clearance, like that guy in Post 12 said.

I saw no witness marks on rockers or cover. But I do plan to start it up without cover to check things.

On those M/T’s look for contact between the edges of the rockers and the bolt hole area at the top of the covers. Would be great if it’s that simple!

Good luck
Murf