Join Date: Apr 2002
Location: Colorado Springs, CO
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Re: Motorcraft 2100 carb on 258 -some additional info
Thanks for all your info on the 2100 swap. I have done this swap following your instructions and it works great for the most part. If you don't mind I would like you thoughts on a related 2100 issue.
I have an 84' CJ7 258 with the 2100. Following the carb swap I used the stock O2 sensor to determine the fuel/air ratio (1.0 being rich side and 0.0 lean). I had read somewhere that an ideal mix would register about .5 (milivolts) on a multimeter directly connected to the O2 sensor. My 2100 came from Texas with #48 jets. I live in Colorado at 7000' so the initial setup was very rich (.88 on the meter) plugs very oily and black. I ordered and installed some #46s and my O2 indicated .65 which is close and suited me fine. Plugs were a bit rich but not too bad. After about one week I retested with the meter and the O2 sensor showed .89, a mixture that was even richer than before the #46s were installed ?????
I am baffled and was hoping you could point me in the direction of what could so drastically change my fuel ratio in a short time. I verified the richness by examining the plugs and sure enough they agree with the sensor.
I am confused and would sure appreciate any input, comments, advice.
Thanks again for all your informative posts.