[KULTULZ]

If INITIAL TIMING is set @ 12BTDC and the engine doesn't rattle under load, there is something wrong.

If the timing marks show that amount of advance at correct curb idle (vacuum signal disconnected), either the curb idle is too high or there is something faulty either in the DIST mechanical advance, DIST install, timing chain and/or damper ring.

The MECHANICAL ADVANCE in the DIST has to have initial advance set @ OEM curb idle or it will show advance (mechanical advance cuts in)(and if the advance curve has not been modified). It has to have a ported vacuum signal to allow the OEM mechanical advance to work correctly.

You can plot the mechanical advance with a timing light and tach.

That has to be one hell of an AC COMP to draw the idle down like that. HOLLEY makes a throttle kicker kit to increase curb idle under engine load.

If the A/C COND install mod doesn't work, I would buy a QUALITY mechanical water temp gauge (for testing) and go from there. If you remove a radiator cap while the coolant is @ 190 degrees, the loss of cap pressure (opening) may allow the coolant to reach boiling point and that could be very bad.

If you could post some photo(s) of the COOLING MODULE and FEAD it would make things a lot easier. I am guessing a lot of air deflectors were not re-installed also. The incoming air has to be directed to move through the RAD. Does you fan have a good shroud?

The way the guy adjusted timing was referred to as POWER TIMING. That may be OK for a hot street engine but not for a driver with A/C.