asiab3 wrote:More tests to come tomorrow and 300 miles over the weekend with plenty of time to stop and adjust. Hope the bus doesn't get mad that I'll be picking up parts for an upcoming engine build…
Sometimes these buses have a tricky way of making our lives better.
I drove three hours in the pouring rain to pick up some NOS single port heads for my build, and they ended up being the small-valve FI heads that I don't really want. So now I'm 100 miles from home, soaked, camping out at a cancelled swap meet. At that moment I had a thought- something like I've read in one of the past itinerary threads: "It's not raining 400 miles from here." Add to that my girlfriend's first birthday I wouldn't have been there for, and baseball spring training, so it's off to Phoenix we go.
I'm still seeing a gratuitous rise in CHTs when I push the pedal more than 75%. I have plenty of power up to there, and I was pulling the Indio grade at 55mph until I chickened out at 430*. The bus absolutely would have made the climb, but I didn't want to risk it. I took that as the sign that I could retard the timing more, and I did. took it from 28ish hose off to 25*btdc. Three degrees of vacuum advance dialed in both times. Temps didn't change very much, only a few degrees cooler. Had a wonderful time in Phoenix with good friends, and even got a bit of a sunburn.
Power felt the same, but I averaged 26 miles per gallon over three fills on the way home. After the third fill up I had to figure out the problem. One of my dual port intake boots has a tiny leak, when I hit it with carb cleaner the idle dropped down :( I rotated the boot and tightened the clamps down and kept the timing back at 25. CHTs stayed below 400 for rest of the desert, but the Tecate Divide saw some 430s when chugging along in 4th until it didn't want to maintain 50 and I downshifted. As soon as I descended into the San Diego area, temps dropped by about 25-30* all around. I could cruise at a real 65 on flat ground with temps not above 380. When I slowed to 60 for traffic and hills 370 was the norm. In the desert, those same conditions saw 410 and 400 respectively.
I'm back in San Diego now, so the stock exhaust comparison will have to wait. I'm curious if you have any thoughts on the differences in CHTs. Ambients don't affect THAT much, do they? Gas was always from Shell stations, always 87. Does air density/humidity make that much of a difference? Do I have a secret stroker motor? Did driving with my shirt off make the bus all hot and bothered? Are we stupid for driving 45-year-old cars across creation on a whim?
Did I mention the bus RAN great? If it wasn't for the gauge readings I'd say it was perfect.