AMC Eagle Den Forum

The Mighty 258 => Emissions/Vacuum Systems => Topic started by: eagle87 on June 02, 2013, 12:29:41 PM

Title: vacuum gauge drops when put into drive?
Post by: eagle87 on June 02, 2013, 12:29:41 PM
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
Title: Re: vacuum gauge drops when put into drive?
Post by: vangremlin on June 02, 2013, 12:51:55 PM
I believe that's normal.  Mine experiences a similar drop.
Title: Re: vacuum gauge drops when put into drive?
Post by: profeagle on June 02, 2013, 02:36:17 PM
Yes, quite normal.  ;D
Title: Re: vacuum gauge drops when put into drive?
Post by: SpreadEagle on June 02, 2013, 02:40:05 PM
Very normal. Not sure mine drops a whole Notch but Mine is a manual. But with a load on the motor normal.
Title: Re: vacuum gauge drops when put into drive?
Post by: eagleman on June 02, 2013, 02:46:41 PM
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.
Title: Re: vacuum gauge drops when put into drive?
Post by: eagle87 on June 02, 2013, 03:23:20 PM
ok mine reads 20 at idle unless in drive at idle then drops a notch, just was concerned it was a transmission actuator problem
Title: Re: vacuum gauge drops when put into drive?
Post by: carnuck on June 02, 2013, 04:21:28 PM
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.