Started by indetrucks, April 24, 2015, 04:43:27 PM
Quote from: Jon S on April 24, 2015, 05:53:19 PMIf you can get vacuum up higher by fine tuning the carburetor air mixture screws, that may help. Also what is the idle RPMs?
Quote from: cadillactim on April 24, 2015, 06:25:53 PMHave you unplugged the check valve from brake booster after a few minutes of idling and listened for the "whoosh" sound? If you don't hear the air sound then your booster is leaking. Just for curiosity sake you might want to replace the check valve with a known good one. Sure sounds like a booster problem.Tim
Quote from: Jon S on April 24, 2015, 06:46:57 PMOne last question. After shutting engine off and sitting for 1/2 hour have you tried the brake to see if you get 2-3 additional vacuum assists before the pedal gets "hard?"
Quote from: curly on April 24, 2015, 07:05:12 PMSounds like the booster to me. Unplug the vacuum port and cap it off. Now, apply the brakes and see if the engine stumbles. If the problem is gone then the booster is most likely leaking around the brake pedal push rod, under the dash.It is hard to tell from your picture, but the vacuum looks to be at 15". That is low, vacuum should be 18-20" at sea level. Are you setting the idle speed in Drive? 450 in Dr will be about 550 or so in Park.T Lewis
Quote from: Jon S on April 24, 2015, 07:25:48 PMI'm suspecting a vacuum leak - cracked hose, intake or carburator gasket, etc. vacuum at idle should ideally be around 20 lbs.
Quote from: Jon S on April 24, 2015, 08:20:35 PMTry tightening the 4 carburetor mounting bolts and see if vacuum improves.
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