9/6/09
The car has seen a fair number of miles since the last post, and a few changes too.
We had an opportunity last month to get together with a bunch of people that Deanna and I hung out with in high school. Hadn't seen most of these people for almost 25 years. The gathering was 175 miles away in Klamath Falls, where I grew up. Since this was a group of people that we knew in the '70s, it seemed appropriate to drive a '70s car. So we did.
After getting the ignition happy again (see last post), I had noticed that the car felt like it was running a bit lean, but not dangerously so. Of course, there's nothing like a 3400 foot (1000 meter) increase in elevation to emphasize that condition. It was quite obvious on that trip that it was definitely running lean now, so after returning home correcting that was a priority.
Even with several years experience with these carbs on the Datsuns in addition to years using and tuning the very similar British version on the MG, I've found that getting the float level set properly (and equally in both carbs) to be tricky. And since the float level is the primary mixture adjustment, if it's off the rest of the carb adjustments are far more difficult. Now that the ignition appears to be dialed in, it was time to get the carbs right.
So rather than trying (once again) the traditional methods of checking the float level, I tried something I'd read about a while back. I pulled the fuel hose from the bottom of the float bowl and connected a piece of clear tubing instead. Left the other end of the clear tube open, but ran it up and alongside the float bowl. Then I cranked the engine over (coil wire disconnected) to operate the fuel pump and fill the float bowls. The fuel fills the tube also, and you can physically see how full the bowls get. No guesswork. I've got several manuals that say the actual fuel level should be 23 mm from the top of the bowl, but don't give any clue as to how you might measure this. But with the tube I can see it.
I did the rear carb first, it was close, about 2 mm low. Adjusted and rechecked, got it right first time. Moved on the the front carb, and found that the level there was at least 10-12 mm low! Took two rechecks to get it correct.
Once that was done, the rest of the carb settings were easy. The results were very good. The car runs great under most all conditions now. No signs of being lean, runs clean and smooth now.
Oh yeah... Other than the lean condition, the car did great on this trip as well.
As if one trip to Portland in early August and then the trip to Klamath Falls in the middle of the month weren't enough, last weekend I drove back to the Portland area once again, this time for my new club's annual barbeque and show and shine. This trip went great, good time, great cars, and the car ran beautifully. The mileage wasn't as good as when it was running lean last trip, but still OK. And it's running enough better that I don't care too much, either.
