On the backside of the throttle body/air handler are the 2 vacuum elbow fittings at the top, why is one vented to atmosphere and the other is not ??
Thx
On the backside of the throttle body/air handler are the 2 vacuum elbow fittings at the top, why is one vented to atmosphere and the other is not ??
Thx
Gary
Growing old is inevitable, growing up is optional.......
S.W. Ohio
The one that is not vented is a vacuum reference port (there are actually two of those, one lower on the intake), and the one with small holes in it is the VST Over-flow port (by design it dumps inside and outside, right above the upper throttle blades, in hopes of flooding out the engine should a VST over-flow occur).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Gary
Growing old is inevitable, growing up is optional.......
S.W. Ohio