Over the past three or four days, the bus has started to run like garbage. I mean, I could still get up to freeway speed (65 or so), but it was very difficult to start and a bit lumpy at idle. Also, the idle was lowering more and more, even though I had it set to a fairly fast idle from the last time I did an emissions test, and also for idle oil pressure in hot temps.
Before I dug into a tune up, though, I accomplished some small, but necessary, tasks.
First, a CO monitor:
Then, clean up the signal and switch wires from my subwoofer install two weeks ago
Much better. Now, onto the tune up.
First step is to remove the air cleaners. Those with weak constitutions, turn away now, because what you’re about to see is the result of a man battling too much blowby with the incorrect tools. You’ve been warned.
With those out of the way, I could start to see the real problems. First, these two brackets that hold the throttle crossover arm were both very, very loose, allowing the arm to flop all around.
I tightened those up with an 8mm spanner. With those brackets being loose, it would be impossible to sync the carbs. Now, to sync the carbs, you need a manometer, or vacuum gauge, of some sort. I vaguely remember spending upwards of $150 two years or so ago on a very fancy 4-channel one that was imported from the UK. Since then, I’d lost track of it, but fixing that simply requires rooting around in my junk for awhile.
I hadn’t touched this bucket in a long time. Could it be in here?
There you are!
It was a little crusty, but I blew it out and shook it around. To work properly it needs to be absolutely vertical, so I set it up on the engine trapdoor cover. I hooked it up to the distributor vacuum ports on both carbs, and gave it a whirl.
Ten minutes or so of fiddling later, and I got it as close as I reliably could throughout the entire range. There’s a little bit of differences through the ranges, but overall it keeps together.
That sorted and away, the last thing on the list was new plugs and wires. I’ve had this box kicking around for a month or two, and it was time to put it to use.
Ranges in different manuals state anything from .024 to .028, so I just picked the middle ground with .026
Old plugs out! #4 isn’t looking too happy, though 😦
If 3 and 4 were equally sooty, I’d chalk it up to driving around for 9 months on unsynced carburetors. And while it’s true that the passenger side plugs are both darker, #4 up there is making me a tad worried. Maybe I’ll drive a few hundred miles and do another plug pull to see if there’s really something going on or it was just the carburetor tune.