Ancient History

[Jeremy]

At 01:46 PM 9/4/96 est, you wrote:
>
>>> What I want to know, is what happens when you have radical
>>> cam timing? This nice puddle of fuel on the inlet valve
>>> gets blown back up the inlet duct when the valve opens?
>>> Makes nice flames, if you don't run an air cleaner :-) 
>>> But this surely can't make for repeatable fuel volume supplied
>>> to the cylinder?
>>
>>As Ralph pointed out, the vacuum goes down at lower rpm due to valve 
>>overlap. A vacuum responsive FI would make the mixture too rich for 
>>the engine to run. I think carburators are more tolerant of this low 
>>vacuum at low rpm because they are passive devices and because they 
>>are less precise in fuel metering.
>
>carbs don't use manifold vacuum to meter fuel.  All they use is the 
>depression created by airflow through a metering venturi.

How about SU carbys? Dont the pistons get sucked up according to
manifold vacuum?


Jeremy