Carb Mixture Tuning

[SuberAvid 617]

I have a question for the carb tuning experts; on my Subie running dual Bing 64 carbs with manual mixture control. My left EGT has always been about 100 degrees hotter than the right EGT. Last winter I was pushing over 1500 degrees every so often so I installed one size bigger jets to both sides and the manual mixture control so I can lean from the normal uncontrolled carb setting. Not too long ago I wanted to start at a little richer point so I raised the needle postion one setting from the middle. It lowered the EGT temps about 50 degrees at full rich but still a 100 degree difference fom left to right. Today I raised the left needle one more position but not the right. This gave me both carbs within 50 degrees.

What do you guys think about running the needles at diffrent positions and tuning it based on the EGT's?

I seem to be able to get more speed with less fuel flow now when I lean it out. It is running about 4.6 GPH at 93 to 95 mph now instead of 4.8 gph and running at just under 1450 degrees on the hottest side. Stratus says to target 1450 to 1500 at cruise and no more than 1550. I haven't taken it quite that high. At 73 - 75 mph it is burning 2.8 to 3.0 gph at 1450 so about .2 gph less fuel for the same speed across the speed range and might be just a little faster at fast cruise pushing 98 to 100 mph at 5 to 5.1 gph.

It seems to perform slightly better with the needles set different but feels a little rougher. I don't know if it is real or just my perception.

[C5Engineer 1170]

Randy it's not uncommon to do that. Of it works for you and your sure there's not an underlying issue such as an air leak somewhere you should be fine.

[akflyer 1427]

Randy,

Just for giggles, did you swap the probes or leads on the gauge to make sure that the high reading was not an issue with the prode of wiring? I went through the same excersize your doing now, and it turned out to the the ETG probe.