Re the dyno session. I'm not going to post the sheets, as I'm not sure that the dyno's calibration was right. The HP & torque numbers are way off the reality. I say this because I had no trouble (on the straights) either staying with, or closing on what are some of the fastest rigs in my class. The good engines are making around 60+hp. I do know that the perennial class champion's engine was setup on the same dyno, and mine was making only 1.5hp less, according to the operator. So the reality is the numbers I got are basically useless. However, I did get the timing set. It's now at 38 degrees total, but I think that maybe to much, 35 is probably the sweet spot.
I'm getting a back fire/pop at very low speed, with closed or very small throttle openings (eg 1st gear going through the pits). As soon as you open the throttle, and give it some revs it disappears. I think this is because of the large chokes are causing poor atomization (lean condition) due to low air speed through the carb.
Now Scotty, about the Weber.
It was running very rich. It had 45F9 idles / 175 airs / 140 mains / F9 emulsion. The idle mixtures were out about 1+ turns each. We had probes into both headers - idle was a touch lean (? see above), mid range was 11.6, and then it went very fat in the top end (10). When I got to the track I changed the emulsion tubes to F16's. This helped the mid range and leaned out the top end somewhat. It will pull from low rpm's in a high (read wrong
gear) cleanly. Then worked on the idle mixture screws (now @ 7/8
). The sync is not spot on anymore, but it now idles not bad at about 2K when warmed up completely. This is probably about as good as that will get because of the 34mm chokes. It's still running on the rich side, so I'll probably try 135 mains. If that doesn't help then next step will be to go to 180 airs, and put the 140 mains back in. Another dyno session will be in the cards before the next race.
Comments Scotty???
