can anyone help with my 3.7l 207 engine?

[J Shepardson]

Hi, I'm having an issue hopefully someone can help me with. I'm working on my venture van, I know this prob isn't the correct forum but you guys are pretty good here.

Whats going on is I ran into some severe over heating problems so tearing down the engine to get to anything led me to changing out my head gaskets, which I figured would be a good idea at the time.

I finally got the engine all back together, changed the oil and added some Lucas, and I'm getting a loud rapping noise from the motor now. I believe the noise is coming from the rocker arms but I'm not 100% sure, everywhere on the engine I place my stethoscope I can hear the loud rapping especially around the front valve cover, upper intake manifold and the fuel injectors. I decided to remove the front valve cover so I can check the rockers and found a few of them have some play, if I remember correctly before I took them out the fronts had a little play and the rears were tight. I torked down the rockers to the specs in the Haynes book (though that book has been wrong about every job I've done in it) 14 ft lbs or 168 inch lbs + 30 deg. laying my stethoscope on the rockers I found one that perfectly matches the rapping I hear, although they all have a rapping sound naturally this one in particular is a perfect match. I've tried loosening the rocker and re-tightening it but the noise is still the same.
I don't know what to do next, does anyone have any ideas on what I can look for if it's not the pushrods or rocker arms making that clack. I'm afraid if I try to drive it something is seriously going to break.

Oh I forgot I did have an issue with one of the rockers on the rear of the engine, it would tighten down way to fast. It hit the torque mark barely after installing it and the rocker arm was still able to rotate so I had to guesstamate it. I'm not sure if that's my problem through the loud rapping doesn't seem to be from the rear.

Thanks guys