Wow. Has it really been six months since I worked on the Amazon?
The 122 has been sitting in the back yard gathering cobwebs since I moved last November. Finally, last week I charged the battery, pulled the choke, crossed my fingers, and- sure enough- the motor fired up on the first try! Yet another testament to Scandinavian reliability.
Unfortunately, the motor was still running rich. I've struggled with my Amazon's carburetion since I got it, vacillating between so rich that I had to drive with the windows down, and so lean that I couldn't get out of the driveway.
I'd already spent countless hours fiddling with various jet settings, needles, and even gone so far as to re-bush the carbs- all to no avail. I finally decided to heed some essential advice regarding SU's: tune up the rest of the motor before touching the carbs!
I really can't emphasize enough how important it is to tune up the rest of the motor before touching the carbs. Here's a checklist:
1. check compression - factory spec is 156-185 psi, with equal compression between the 4 cylinders
I got readings of 160, +/- 5 psi between the cylinders
2. valve lash - I set mine to 0.020 (cold) using the "Rule of Nines" method
I used 0.020 "go" and 0.022 "no-go" feelers
3. points and condenser - replaced (point faces were pitted) and set to 0.018
I tried to file the point faces flat, but the pit was too deep
I used 0.018 "go" and 0.020 "no-go" feelers, cam and rubbing block were lubed prior to installation
4. distributor cap, rotor, spark plugs, and plug wires- replaced distributor cap and rotor (carbon traces and pitting were evident on both). I looked up the Bosch number on my distributor and got parts locally because I was impatient, but honestly, iPD's tune up kits are a hard deal to beat. I cleaned and gapped the plugs to 0.028 and "refurbished" the plug wires and boots -- I was too cheap to replace the plug wires (which look good), and instead, snipped about a 1/4" from each wire until I got to what looked like "fresh" copper and screwed the plug boots back on.
filing the contact faces just ended up scoring them... and isn't that a crack, anyway?
I installed plug wire separators for extra insurance against misfires
6. timing - OK, I fibbed. I still need to get my hands on a timing light.
7. fuel filter - replaced
8. eliminate vaccum leaks - replaced PCV valve and hose
not sure if this was necessary, but it was cheap insurance
9. finally, tune the carbs - cleaned, re-bushed, replaced throttle shafts, set float height, re-centered jets, matched piston drop rate, sync'd, and set mixture
Lesson learned - it's impossible to tune SU's without having the rest of the motor in good order. After all of that, the Amazon seems to be running like a champ! (Or at least like what I imagine a 44 year old car should run like.)