QuestionI have rebuilt the engine of this '70 E-type. New pistons, rings, valves, seats, guides, springs, bearings, etc. The crank, flywheel, damper and clutch were balanced as well as the rods and pistons. The twin Zeniths were professionally rebuilt and have no adjustment for mixture. The clearances are set to 0.004" and 0.006". I had them set at 0.012" but the valve were so noisy I changed back to the current setting. I have an upgraded coil (flamethrower) no ballast resistor. I have balanced the carburetors and adjusted the timing. The car drives wonderfully but I can not get a smooth idle. I have had the vacuum check and it is correct and can't find any leak or loose hose. At idle the tach will "bounce" a little but less since the valves were adjusted.
Any thoughts on what I should try next? I owned one of these exact cars years ago and the idle was fine on it, though it would tend to speed up over time.
AnswerHi Antony,
When you say the Stromberg carbs are not adjustable, do you mean they are the Strombergs that have the press in needles and are not adjustable. Did you check the temp compensator and the idle trimming adjusting screw next to the compensator?
Do this, remove the air filter box and when it is warmed up and idling slowly restrict the air going into the carbs with your hands to see if it smoothes out or speeds up at any time as you start slowly restricting the intake air. Another test is to use a small propane torch (NOT LIT) and bleed a little raw propane into each carb to see if you can smooth out the idle. These are normal tests for intake leaks and lean mixtures.
One other thing, check to see that the upper cam chain is correctly adjusted since the valve adjustment has affected the tach generator. If that upper chain is loose it can affect idle too.
Howard
