Hi All,
This condition seems to be getting common.
A few weeks ago I reported my Healey, that has usually revved freely to my common 5K rpm shifting, started to have difficulty moving to 4K rpms. It also started to backfire through the carbs when not quite hot and plugs 2 & 3 began to burned black. Finding the timing (Crane CD ignition and 40K coil) on the money at 15 BTDC, with smooth mechanical and vacuum advance movement, I addressed the carburetors and found a non-consequential amount of sediment in the bowls. After resetting the carburetors and adding 93 octane from another station, the car seemed to run better but not as before.
A few days ago, the idle seemed unstable after a drive and decided to reset the mix. Pulling the plugs again, plugs 2 & 3 again were much darker then the others. Pulling the pistons to establish a starting point by having both seats at bridge level, I pushed both choke (separately) to assure both seats moved freely. Although the rear carb seat dropped, the front seat did not move and I used a plastic punch required excessive force but the seat moved.
Since Jeepster and others seem to be experiencing similar surprise (seemingly non-developing) conditions, I am beginning to wonder if their is a common cause in play. We are experiencing this condition over geographic areas but can not rule out a common fuel additive that is reacting with the spring, diaphragm, or seat and causing higher resistances in seat movement or even causing them to frozen in place. I appreciate that it is just a suspicion with little to base it up but I thought I would extend the suspission.
Ray (64BJ8P1)