High idle with no pressure on pedal

[Sean Stacey]

Just replaced vacuum booster on my 74 Dart, old one was bad. My problem is, with the vacuum line hooked up to booster and no pressure on brake pedal the engine idle will increase about 200 rpm. Once pressure is applied, engine idle drops in rpm's. Would the correct push rod length have anything to do with this? I am running a bigger cam 282 dur/ .491 lift and about 15 on the vacuum gauge at 900 rpm. Any thoughts? Might just switch and get rid of the booster all together. Sean

 

[jerry6]

15 of vacuum should be good , I had a problem like that , don't remember if idle went up when I pushed the pedal or let go but it went up at one one or the other , leaky booster . Had it rebuilt

 

[gtsdude]

Sounds like vacuum leak in the booster.

 

[Bad Sport]

How is the check valve, is it working?

 

[salinasjoel]

If you pull the connection from the booster and plug it how is the idle? If you aren't married to the power brakes I'd ditch them for sure.

 

[Woods74]

Spray some starting fluid around the engine bay, if it revs up you have a vacuum leak there.

Just say 'NO' to power brakes, aka sponge bob square pedal.

 

[Sean Stacey]

Thanks for the input guys. Car runs awesome with the booster disconnected. The booster I bought was a rebuilt one and faulty. Gonna switch and go with manual brakes. Just one less item in the engine bay. Thanks again.