Howdy back Firetox:
If "that thing" bolts directly to the exhaust manifold exit, it is the Cat on these engines. FoMoCo put them there for a faster burn on start up. The Cat, on these engines is not down stream, in a more normal location like other cars.
To adjust your initial timing, you'll need a timing light, a golf tee and a distributor nut wrench. Start and warm your engine to operating temperture, Stop the engine, disconnect the vacuum line to the carb and plug it (I'll bet your were wondering what you needed a golf tee for). Find the distributor clamp nut, under the distributor body toward the firewall. Loosen it enough so that you can just barely turn the distributor body by placing your hand on the vacuum cannister. Do not over loosen. Now attach your timing light to the #1 plug wire and the battery making sure you clear the fan. Clean the timing tab on the front of the engine and highlight the timing mark on the damper with a piece of chalk. Now restart your engine and note the current timing. Now put your hand on the vacuum cannister and gently and slowly push it toward the block, noting the change in the timing mark as you go. Set the timing at about 13- 14 degrees before top dead center. Shut off the engine and tighten the hold down clamp bolt. Restart the engine and recheck the initial timing. Now reconnect the vacuum line to the carb, dissconnect and remove the timing light and take it for a drive, listening carefully for knock or ping, mostly like at lugging engine speeds. If you do get any, you can; stop lugging the engine, down shift, OR retard the timing a degree or two, use an engine fuel system cleaner such as Gumot or Techron, use a higher octane gas, use a colder thermostat, a colder heat range spark plug or any combination.
On the wheels, any 4 x 4.25 Fox bodied Mustang wheels, '79 and later will be a direct bolt-on. There are many choices in either 15" or 16". You should try to maintain the same overall diameter as your stock rims and tires. For performance go with the smallest, lightest tire and wheel that will meet the performance potential of your rig. Any more and you're probably throwing money away and losing performance.
There is no need to upgrade to a 5 bolt axle and wheel in your application. The 4 bolts are way stronger then anything you will be able to give them. I have yet to hear of anyone ever breaking a 4 lug wheel, or axle. Have you? And 5 bolts are heavier. Lighter is better given our relatively small engines.
Adios, David
I'm running a Blaster 2F coil, a MSD 6A box, MSD Duraspark II adjustable timing module, a now hard to find Ford Racing Duraspark wiring harness (bigger wires, better spark) and it's great!
