Hi guys -
Thought I would continue on this thread with developments, see if anyone has any additional thoughts or input. I'm far less worried about The Noise now than before, but there is nothing wrong with a little academic discussion.
http://www.sacsaabs.org/sacsaabs.org/mi ... ningaf.jpg
The above is a shot of the Autometer A:F gauge zip tied to the steering column. Hasty installation, but it does the job and did not require modifying the car to do, and I like that. The gauge sits about where you see at idle, which is a few bars into "rich." Under heavy acceleration, the gauge dips down into the high end of "stoich." I think that is probably richer than it needs to be for ideal economy/power, but I'm unsure yet whether I need to adjust the idle mixture, increase the timing, or up the plug gap. It's running strong as-is, but I think there are still some ponies to unlock. I probably should see how things change in the upcoming Sacramento summer.
In any case, I've been driving it as often as possible in the past couple weeks, now that I am less afraid of the engine blowing up from The Noise. What I have observed is that The Noise will go away entirely after a few minutes of freeway driving, and then return after a few minutes of surface street driving. Based on other factors, it seems like heat makes it stop, then once things cool down from going at a leisurely pace it returns. I am wondering if maybe the ridiculously oversized transmission cooler is the culprit (or at least a component), so I'm looking into a thermostat to help the transmission get up to temp quicker. IMHO, it should have one anyway so why not?
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If you're interested, here is my fuel pump install:
http://www.sacsaabs.org/sacsaabs.org/mi ... lpump1.jpg
The fuel pump is now no longer fastened to the floor of the car. There are rubber isolators sandwiching the floor of the car, and large washers "hang" the pump from the isolator in the trunk. There is no metal to metal contact anywhere. The rubber is part of a conveyor belt, the same material I used to make the spring isolators on my XR4Ti. It's super durable. Unfortunately, it may be too durable as it doesn't do a perfect job of isolating the pump. I may need something softer, at least on the bottom. It does a pretty good job, though, and now I'm left primarily with noise and virtually no vibration. The pump is still loud, but not buzzy. I think most of the noise I'm hearing is from outside the car, rather than noise echoing through it.
http://www.sacsaabs.org/sacsaabs.org/mi ... elays1.jpg
These two relays are stashed by the brake master cylinder, the interlocking relay mounts are from a Saab 900 but I can't remember what part... maybe a passive ("mouse") belt module? In any case, that big grey wire provides battery power to both of them. They are grounded by the battery, and pulled down by the ignition switch. I didn't like the idea of running anything significant through the 50 year old switch, so it's just whatever tiny amount is needed to pull down those relays. The grey relay is a dual-throw and powers the oxygen sensor heater, narrow-band A:F gauge, and Pertronix ignition system. The black relay is single-throw and powers the fuel pump. Some day I will redo this wiring so the grey is the fuel system and the black the ignition, but it was installed in stages and this is how it worked out.
I've been trying to come up with a way to tie the fuel pump to engine operation rather than the ignition switch, but not trying that hard.

As it is, when you turn the key the fuel pump starts but that could be dangerous since someone could run the pump with the engine off, or worse the pump could continue to run in an accident. There is a kit to tie the pump to the oil pressure switch, but that seems less than ideal (although functional...). 8v Saab cars have some special relay that closes with a tach signal and retrofitting that is my first choice - I just need to figure out what that tach signal looks like, and maybe how I can use it to also run a tachometer. I also want to be sure there is some sort of replacement option when my supply of 8v fuel pump relays dries up.

Once I get this worked out I'll rewire the relay blocks accordingly.
I also need to wrap up the red wire that runs over to the Pertronix, but I am thinking about relocating the coil from the side of the engine to the shock tower so I haven't done that yet. Seems like having the coil bolted to a heat sink rather than a heat soaker is desirable.
I bled the brakes on Sunday, and my next project is replacing the front suspension. The previous owner installed new KYB shocks, but every single bushing on the car is destroyed and it creaks like my grandmother at the slightest provocation.
