knocking noise under valve cover once engine gets hot

hey so i just removed an engine out of my 86 tv (180,000 miles) because it was just trashed. it ended up having a valve seat blown out. so i pulled the engine, switched some accessories over to a newly cleaned and rebuilt engine and hooked it all up. I ended up replacing half a dozen connectors, a whole dozen hoses and lines in the process. so now where i am at is an annoying knocking/tapping noise sounding like it is coming from under the valve cover.

this noise only occurs when the engine has heated up and is driving. it wont occur when it is in park or neutral. so what are my options in terms of what this could possibly be?

I've heard it's easy to put the rocker in upside down.

no im sure that isnt the case. whenever i adjust the timing with the distributor, itll will calm down, but it doesnt matter how much i turn it to the right, it will still knock...

Try disabling cylinders one at a time by pulling spark plug wires. Rev the engine each time a cylinder is disabled to see if the sound diminishes. If you find the knock to significantly reduce with a particular cylinder disabled, then the knock is almost certainly a bad rod bearing for that cylinder. For more information check this thread: http://www.toyotavantech.com/forum/s...-in-bottom-end

So she starts up fine, runs well 20 miles, 100 miles etc, until I turn her off and then start up again. A clacking type sound shows up, fairly loud from the top of engine I believe. It increases in repetition when I rev up, and slows down when throttle is idling. Basically a clackclackclack to clack...clack..clack.

Engine is running a little hot, but nothing too far past half on the temp gauge.

Friend tells me is a rod arm that needs adjusting. Dies this sound right? Anyone else have this issue? Tried a search but not quite sure what I'm dealing with.

No loss in power and overall running very well.

The 4YE engines have hydraulic lifters that control the pushrods. Could be one or more of your lifters is bad and bleeding out or leaking down oil or clogged? The valve head needs to come off in order to remove and inspect the lifters. I had a noisy one on cylinder one. I was able to make the noise go away by running marvel mystery oil in the crank case as directed on the bottle along with Mobile 1 10w40 synthetic oil. The oil method will cost much less in money and time to try than the head removal. Hope this helps.
Blake