vacuum gauge drops when put into drive?

[eagle87]

ok, so at an idle my eagle has the vacuum guage reading at half way, however when its put into drive it drops one increment on the guage, is this normal? if not any ideas what is causing this? car is completely stock, new vacuum lines, working carter carb, new carb gasket, idles at about 600 in drive

[vangremlin]

I believe that's normal.  Mine experiences a similar drop.

[profeagle]

Yes, quite normal. 

[SpreadEagle]

Very normal. Not sure mine drops a whole Notch but Mine is a manual. But with a load on the motor normal.

[eagleman]

That is the way it should be and as you increase rpm's it will drop futher then return to about half way at idle. Should read around twenty or so at idle.

[eagle87]

ok mine reads 20 at idle unless in drive at idle then drops a notch, just was concerned it was a transmission actuator problem

[carnuck]

Nope. When you engage the transmission into gear the back pressure of the trans pump makes the motor slow down and results in the vacuum drop. When I put my Eagle in drive, the idle is so low you can barely feel the 727 engage due to a higher stall converter. Figured out I'm getting close to 20 mpg highway now though.