Radiator Ducting?
 

Whats the best/easiest way to improve the radiator/oil cooler ducting on an 84? (running earlier radiator/oil cooler setup)

If your talking about the car in your sig I would say get a bigger radiator first. The biggest thing with ducting is to make 100% sure that all the air that enters the grill opening has to go through the rad or cooler to get out. Fill every crack, gap and hole with something.

on my 82 turbo i put a large rad in (29x19) and used an aftermarket bumper to get a better duct into the rad. Then i framed the opening in with aluminum so that 100% of the air going into the nose was directed at the rad.

My oil cooler was moved to the rear of the car and hangs out below the bumper. I actually think that with the higher volume of oil and the amount of air that it receives, you need to have the thermostat in the cooler.

I also added a splitter in the front which helped immensely.

With these additions, using a 160deg thermostat with 3 - 3/16" holes I was able to keep the car no warmer than 175 to 180 deg and the oil never went above 180deg in 90deg ambient temps on the track.

In racing trim the oil is the key to keeping a FB, FC, and FD cool.
Ducting as mentioned above is essential.. allowing the air to get through the radiator, and not bypass is all good.
Consider adding an additional oil cooler. A FB or FC cooler added to what you already have is a HUGE benefit if you have temperature problems.
In EProd, they were originally throwing 3" dual pass rads at all the rotaries, and they were unable to keep water temps under control.. even with tons of ducting and air flow work.. the engines at 10/10ths would start getting too hot.
Add a second FC oil cooler.. or FB.. and voila.. Temp problems go away.

The water courses around the periphery of our engines.. the oil is shot into the core, and cools the rotors, as well as lubricates things. That superheated oill in race form is not cooled enough and the block begins to heat soak.. the water cant pull enough heat away.

Extra oil cooler is the fix for engines that are unable to control temps. (this is assuming its tuned properly, and there are no issues with the internals etc. And you have already ditched the stock rad, and are using a dual pass.)

Okay... back to the orginal question, What is the easiest/best way to seal off and improve the ducting on an 84 using an 81-83 radiator/oil cooler setup?

As far as upgrading radiators and oil coolers Ive already done all I can as class rules limit me to running stock coolers (politicing to allow better radiators atm, followed by oil coolers), PO of car swapped from 84-85 beehive oil cooler to a 81-83 split radiator with oil cooler below and frankly unless I find hard data saying ones better then the other I see no reasson to change it back.

The rad cooler setup you have now is mandatory IMHO. THe beehives all should be smashed with large chevy engine blocks dropped from a building. :D

If you are racing only, a couple methods.. if you have small air gaps.. aluminum ducting tape on the windward side (in front of the radiator) between the edge of the rad and the car. Combined with helicopter tape/racing tape will allow you to seal smaller gaps effectively, and still allow you to take things out easily without any drama at the tracik as needed.
Larger holes, and or large areas that dont match up properly, some 1/16" aluminum panels will work fine. Pop rivit them in to block off the air. Put a thin bead of silicone between the panels before final riviting, to help seal them, and prevent vibration issues.