Hey, realize this is an old thread and probably not relevant to the originator any longer so I guess this is just a little FYI. I had an early Geo metro I wanna say it was a 1990 or 1991 and the cool thing about these older models was that Suzuki had an adjustable cam sprocket on that G10, if you pull the cam gear off and inspect it, you will find it has an extra notch that is if I remember correctly 3° offset. I don’t know if they still do but Suzuki used to race these three cylinders and the other notch is the setting that used for racing
. As far as mpg I never clocked it, so I don’t know if it improved or gotten worse. Either way I was still getting killer gas mileage, and with the offset cam timing once that thing hit 90 did not want to slow down. I had a lot of fun with that car.
Now part two is that I arrived here in the first place, because I am trying to figure out the answer to that same question that started this thread. If I’m trying to increase my mpg, should I retired or advance from what I remember on the metro I believe I need to go 3°, but I can’t remember which direction or if it would improve gas mileage at all, but my assumption is that the more efficient burn That this adjustment I believe creates would increase gas mileage as well. So if anybody has the answer, let me know please. My current project is not a metro by the way, but a single overhead cam YJ so I’m assuming the results would be ballpark similar.