On my 1980 242, I have swapped out fuel distributors and need to check(and possibly adjust) the fuel mixture. The Haynes manual says to attach a dwell meter to the red test lead on the drivers side of the engine compartment and with the O2 sensor disconnected I can adjust the mixture until it reads correctly on the meter. When I try to adjust it, I dont see any change on the meter. I get a reading of about 55 degrees, which I believe needs to come down just a little. Also, when I reconnect the o2 sensor, The dwell reading goes down all the way and pegs the meter and the engine starts to run worse. I guess at this point it is running too lean. Does anyone know why it does this?

Am I doing this procedure correctly? I do have an exhaust tester at my disposal, but I dont think I have a test port before the cat.

Thanks...