[TR] TR6 evaporative filter - function or setup question

[Dave1massey at cs.com]

In a message dated 4/27/2010 3:45:08 PM Central Daylight Time, 
mhooper at digiscreen.ca writes: 
> Why does this have such a huge impact on the engine (especially idle) 
> when the
> pipe to the valve cover is unplugged? It really seems to unbalance things 
> a
> lot. The carbs are newly rebuilt with only less than 1000 miles on them, 
> so I
> don't think anything is jammed open etc.
> 

The source of suction is the venturi in the carburettor.  Introducing a 
significant amount of air (compared to air flow at idle) will change the 
fuel/air ratio.  The carb is calibrated to compensate the typical amount from the 
crankcase and the charcoal canister based on the restriction of those two 
paths.  Disconnecting the hose from the valve cover changes that restriction 
and will increase the amount of air leaning out the idle mixture.  Plugging 
the hose will reduce the amount of air causing the idle mixture to be rich.  
It's all a delicate balance.

Slante

Dave