Re: [MBZ] Four barrel enthusiast

[Peter Frederick]

Not actually a rich mixture, rather the charge density is so low it 
won't burn properly -- high CO and high unburned hydrocarbons from the 
very high manifold vacuum (and hence very low combustion chamber 
pressure -- usually below atmospheric).

The slow close throttle prevents some of the pollution.  On the KE-Jet, 
the fuel is shut off instead, which works better -- you get proper 
closed throttle deceleration.

Peter