Ferrari Mailing List: Quirky stuff, 308 idle woes

[Rick (rolindsay]

Further to the 308 idle-down issue; a few more observations and realizations.

1. The car only has the idle-down problem when at operating temperature. I just realized this (duh) because it only happens on a drive - and after - when the engine bay is hot.

2. I should have been more clear.  The problem happens when the air cleaner BASE is on the carbs, but that may be a spurious and misleading data point.

3. A friend has my bore scope camera and he's presently in Europe.  When he returns I'll be able to see all the linkage movement with the air cleaner base on.

4. Since this problem acts like a vacuum leak - kinda - I'll temporarily disconnect and plug the brake booster vacuum line ...just as a methodical test.

5. Perhaps the issue is NOT the air cleaner but a heat issue, and the engine only gets to operating temperature with the cleaner on.  I won't drive it with cleaner off.  Webers spit too much fuel vapor to drive with the air cleaner off.  Serious fire hazard.

6. I think I will fashon a long wire with a hook end (read: coat hanger) to pull gently, each carb linkage in turn, to its idle stop to see if anything might be binding once hot. At no-load, even a tiny error in throttle position can make a big difference. 

7. Yes, time and detective work is needed.  FWIW, the car runs fantasticly.  I just need to correct this pesky idle-down problem.  And heat may be the clue to finding the solution.

My thanks to those offering advice.

-rick

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