Fine tuning an engine rebuild
 

I am having trouble fine tuning an engine after a rebuild due to two broken cylinder head studs. Car is a 1980 ROW 911SC. While it was apart I had the heads rebuilt, replaced the cams with 964 profiles and installed an SSI exhaust system with no cat. This car has CIS with no oxygen sensor, and all the smog pump set up has been removed due to the SSIs. Also drained the gas tank and put in a few gallons of Chevron supreme. Here is my problem.

Between three things; setting the timing, setting the air/fuel mixture to 13.5 (or near lambda 1), and setting the idle speed I can only get two out of three. I started out with 16 or 17:1 air/fuel mixture, and when I would richen it the idle speed would drop and the engine would die, and would not start again until I set the air/fuel mixture back to where it was before. I then decided to check the timing again, the marks were a little off, maybe 1/4" or less, so I turned the distributor clockwise (advanced??) till the timing marks lined up perfectly. Then the idle speed would drop, engine would die, and again would not restart until I reversed what I did with the timing... very frustrating. So I decided to crank the idle speed way up, to ~1500 rpm, set the timing and the air/fuel mixture dead on so that everything was perfect, then I tried lowering the idle speed again. It would not get anywhere near 900rpm, around 12-1300 rpm it would die, then again would not restart until I again changed the timing (rotated the distributor counterclockwise again (retarded??)). By the nth time of doing that I was at my wits end and put everything away before I started throwing tools around the garage.
Got any insights as to what my problem might be?? If you do I would sure appreciate the help. Thanks.

You should fine tune a warm engine, make sure it is at operating temperature first.

Make micro adjustments to the Air Fuel and then adjust the idle speed up, then check and adjust timing, every adjustment to one will as you know effect the other. You should also double check all you vacuum lines to make sure they are routed correctly or if you removed lines that the openings are plugged, especially the ones in the back by the throttle body.

You may have to simply let it run in a bit before you try to fine tune it.