What is the best way to install the distributor on a /6 with the engine in the car? Obviously line up the tdc mark on the pully (and line up the dizzy rotor with the mark on the dizzy) however if I do that couldn't potentially be 180 degrees off?

Uhhh....probe in the #1 spark plug hole to see if it's on TDC & you're good to go....

The piston will be at TDC twice during the 4-stroke cycle. Once at end of compression (A) and once at end of exhaust (B). You will want to install the distributor with the rotor pointing to no. 1 spark plug wire on the cap with no. 1 cylinder at (A).

There are various ways of identifying the status of the cylinder. This is the easiest method IMHO:
- Remove no. 1 spark plug.
- Insert a length of hose (approx. 2') so one end butts up against the SP opening.
- While observing the timing mark on the crank pulley, rotate the engine (e.g. manually or push vehicle forward in 5th gear or bump engine with remote starter switch).
- When pressure is felt at the end if the hose, the piston is moving upward on the compression stroke.
- Position the crank pulley further so the crank timing mark aligns with the split in the crankcase (noon position).
- Install distributor so the rotor points to no. 1 SP wire position on the cap. Since the dist. gear is helical cut (teeth are angled), the dist. shaft and attached rotor will rotate slightly during installation. You may have to compensate so the rotor ends up in the correct position opposite the notch on the top edge of the dist. housing.

This should be close enough to run the engine. Have a timing light connected and the dist. hold-down nut loosened slightly so the dist. can rotate to set the initial timing after the engine runs.

Hope this helps,
Sherwood

Chopsticks?

In the amount of time you took to ask and read the responses you could have installed, tried to fire, and if no fire remove and rotate fan 360 and tried again...

and close your eyes ,you wont need um anyway

You didn't say if this is a stock /6 or one from a 911. The stock /6 does not have a mark on the pulley (I believe)-you need to look for the mark on the flywheel thru the access hole. It's easier to see anyway.

If you aren't keen on sticking something in the plug hole, pull the valve cover for the 1-2-3 side. Find the timing mark and see if the intake rocker arm moves as you turn the engine back and forth around the mark.
If it does, turn thru one revolution of the crank.

Make sure the rotor is aligned with the mark on the distributor body when you go to install it and turn BOTH of them together as you slide it in. Now it should be close enough to start and set with a timing light.

Oh for the love of God, bring the # 1 cyl. to the top of its stroke, spark plug out.
Get a piece of hose 2 feet long, about 5/8" diam.
Put one end of the hose flat against the plug hole and the other end in your mouth.
Blow into the hose. Blows easy ? 180 out. Resists blowing ? TDC !
Point the rotor at the #1 wire. Done.