Compression test will tell you a lot.

 

is it just me or in your second video is the flex plate wobbling around?
with the engine off, try using a pry bar to hold the flex plate in place and have someone use a ratched and socket turn the engine over

 

it did look like a slight wobble, i tried to pry a little myself with no movement. i think i need to disconnet the converter bolts and then see if i get play.

 

Agreed that it's hard to tell sometimes from a video, but that REALLY doesn't sound like bottom end to me. Wrong frequency and "rhythm" if that makes sense. It seems loudest underneath which seems to indicate that the top end/valve train is ok. I'm going to throw my vote at the flexplate area as others have suggested.

 

did you get a chance to check if they were tight? and when you checked them was they any marks on the heads. just the timing of the noise could almost be one bolt that backed out and is just hitting a certain spot every revolution

 

no chance to work on it, family visiting. i did fire it up and let someone else listen. they think its not lower end also and say it sounds loudest under truck, but seems to sound like its coming from the front of motor to them when under the truck. i didn't think it sounded like it was from the front.

 

hey, it was pointed out to me that these are ls6 springs. i'm reading that the lift is good to about .570ish but most threads are advising much less. i have comp xer273hr cam which shows .581/.588. this was all done by PO so i'm discovering stuff as i break or upgrade.

are yellow springs only the ls6 springs? how bad is this setup on my cam?

 

Bad. You may have floated a valve as those springs are not strong enough. Usually when a valve floats it contacts a piston and bends a valve.

If that's the case. A compression check will show a cylinder with low pressure.

 

i did my compression test, idk if i completely trust i was getting a good seal on the spark plug holes, but from what i did get it looks like the back cylinder on passenger side is showing lower. i was getting anywhere from mostly 170-180, 165 and that cylinder best i got was 150 once. several other tries i got 130's. i tried it motor cold, and again warmed up just a little.

i also unbolted converter and pryed on the flex plate, no noises there and started motor with converter off with no change in sound.

so should i start with pulling head or dropping oil pan? or something else?

 

Personally, I don't like repairing engines in the chassis. Easier to deal with everything on a stand. So if it were me, I'd remove the engine then tear it down.