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Discussion Starter #1
I wrote about setting the mix on a SPICA in another post. I have now driven far enough to see the change in gas mileage (or whatever one calls it in countries with metric) and it's considerable. With the mix set as carefully as I could with no load on the engine, using a digital tach to see the revs, I was getting 20 MPG in rural driving (not much stop and go, but not highway). After setting it under load, 24 MPG. 20% difference.
 

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Here you go. Actually, I learned this method when I worked on cars with SU carbs, which have a needle that moves in response to throttle settings and controls the amount of gas entering the air stream. There really aren't many fuel systems that can be easily adjusted this way (any system that relies on jets, such as the Weber, takes forever and a pile of jets) but it seemed logical that it would work on the SPICA.

To set the mix, take out a plug and have a look. If black and sooty, you are running rich. If chalk white, lean. Remove the lead on the cut-off solenoid, loosen the locking ring, and turn the solenoid 1/8 turn (judging by the spade terminal on top) clockwise to lean the mix, CC to richen it. Snug the locking ring up hand tight, and go for a drive. Get it hot, and then find a gentle slope. Approach it at the bottom in third gear at 25 MPH and accelerate slowly to 45. Let's assume you had a lean condition. If there is no hesitation, you are correctly adjusted. (Lucky, if you get it the first time.) If there is hesitation, stop and turn the solenoid CC 1/8 turn, go round the block using lots of revs to keep the plugs clean, and repeat the process. When it accelerates with no hesitation, lock the ring. You're done. Now, assume it was rich. If there is no hesitation on the first run, turn the solenoid clockwise 1/8 turn and repeat the test. When it hesitates, turn the solenoid CC 1/8 turn, make one more run to be sure, and lock the ring. This is harder to judge, as it may not hesitate on acceleration, but see next paragraph.

As I said on my first post (above) I was just about a turn rich before this process. I actually got it too lean, which is characterized by wonderful acceleration and top end performance, a very lumpy idle, and missing at constant throttle below 3000 RPM. I cured that by turning the solenoid 1/8th turn back (CC). I also discovered that if you snap open the throttle when the car is in neutral and the engine immediately revs up like a carburetted engine, you're too rich. There should be a brief hesitation.
 
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