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Jedi Trainee
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67 etype, 82000mi. Thank you all for the suggestions, most focusing on mixture and choke actuation. Began SU tuning 45yrs ago on Volvo PV544, last 20 yrs Elite, TC, Healey, Jag and up until now never been so far off as nonstart. Live and learn I have redone carb tuning twice now, focusing intently on mixture, using one turn past no more RPM increase as well as pin lifting and direct piston lifting, as well as insuring at full choke dash lever getting full carb choke lever movement. Still pretty much same, stumbles for a while then all six go and runs great when still cold(choke on) and fires right-up(no choke) when hot. (My cold start-up ambient is 60deg). The cold front miniheader during stumble suggests front carb? four nuts holding carb to manifold took at least one full turn to tighten but no effect. Will try propane torch gas around carb to see if RPM speeds up, maybe worn throttle shafts or other such air-leaks when cold that when hot close-up. Took out front plug, connected and grounded and spark occurs so probably not electric. When running at op.temp., full choke lever causes near stall stumble. Open to any and all suggestions, thoughts please. thanks in advance (BTDC)
 
Suckin' air past throttle shafts? Mebbe pull the carbs off completely to check the gaskets: If the front one was that loose for any period of time the gasket could be junk. If you know to hunt it with propane, you've got this under control.
 
Call me crazy but I am still blaming the gas. I filled my 68 E up at a different gas station a couple of weeks ago and now don't have near the spit & sputter I did last month. Haven't driven the other cars ( TR3 & Jensen) enough to fill them up yet. I have played with SU & ZS carbs for 30 years myself, I set my chokes pretty full so I know when they are engaged. But always open to new ideas.
 
If your throttle shafts were significantly leaking air, you would have a very erratic idle speed and not be able to propeerly set the fuel air mixture. Your idle speed would be abnormallly high.
 
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