>It has a passage on the underside of it that coolant passes through.
>
>I assumed this coolant was there to help cool the manifold.
>Or at least to make it an even temperture and avoid hot spots.
*************************************
This pre heating passage on ANY manifold is there to heat the spot to help
aid in fuel vaporization for more complete combustion (better emissions)
and smoother idle and off idle operation. PROPERLY designed it has little
effect on full throttle acceleration because at those velocities the
manifold would cool down from the resulting volume of air and fuel rushing
through it at reduced vacuum. Any street engine should have some sort of
manifold heating for a smoother running, more efficient (d**n there is that
word again :-}) streetable engine. Removing this pre heating will result
in increased fuel consumption (because the carb will have to be set
slightly richer for idle and off idle running to compensate for the loss of
vaporization). It will usually also cause the engine to run a little more
rough at idle and in extreme cases cause an off idle stumble (if the leaner
condition is not compensated for)
There is really NO practical reason for disconnection this pre heating on
ANY street driven vehicle. On a race car, driven rarely at idle or low to
medium revs, this pre heating doesn't matter and is unnecessary -
Barry Schwartz (San Diego) bschwart@pacbell.net
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