RE: [Chevelle-List] Vacuum problem?

[396guy]

Craig,   I assumed the cowl vent was open all the time and not shut all the time; although the poster didn't specify which.  May be a bad assumption on my part (?)  Being open all the time would be an indication of no manifold vacuum at the valve to close it under normal driving conditions or when at idle. I don't know the vacuum hose routing from the flapper valve but the line may be pinched or the valve is bad.  Since you would normally have 14-18 inches of vacuum at idle, that should be more than enough to close the flapper valve.  I would assume it opens at somewhere between 5 and 10 inches of vacuum when you nail it.   Whether this has anything to do with the carb secondaries I would doubt since they're operated at the carb via the spring - unless the carb has recently been rebuilt and not put back together properly but I think they're be a sucking sound you could definitely hear.  Unless you can feel when the secondaries open under a load at WOT, I don't think you'll see them open just winging the engine while you're watching it.  And I sure hope you're not testing it like two guys I read about that got stopped in a car with the hood off.  One guy was sitting in the engine compartment to verify the secondaries were opening while the driver was hauling a$$ down the road!   Dale McIntosh ACES #1709/TC #92 Gold 67 SS/67 Elky http://www.dalesplace.com http://www.team67.com http://www.midwestchevelles.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Craig A. Ellis Sent: Wednesday, September 04, 2002 7:42 AM To: '[EMAIL PROTECTED]' Subject: RE: [Chevelle-List] Vacuum problem? Dale, that's what I've always thought but I think the cowl induction system works manifold vacuum drops - as in when the throttle is punched wide open. My understanding is that vacuum is what keeps the cowl closed - that's why is snaps open when you turn off the motor. I am not a mechanic and could be wrong about all this - but the logic of the system seems to indicate this is how it should work.   Craig E -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of 396guy Sent: Tuesday, September 03, 2002 6:53 PM To: [EMAIL PROTECTED] Subject: RE: [Chevelle-List] Vacuum problem? I wouldn't think so it'd be possible to generate too much vacuum.  Both my cars (396 and 327) pull about 17/18 at warm idle, 15/16 cruising at steady throttle and jumps to 24/25 range when decelerating.   You problems sound like lack of vacuum - bleeding off somewhere. Dale McIntosh ACES #1709/TC #92 Gold 67 SS/67 Elky http://www.dalesplace.com http://www.team67.com http://www.midwestchevelles.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Craig A. Ellis Sent: Tuesday, September 03, 2002 8:37 AM To: Chevelle (E-mail) Subject: [Chevelle-List] Vacuum problem? Is it possible to generate too much manifold vacuum and, if so, how does one diagnose the problem and remedy??? My cowl induction has stopped working and my vacuum secondaries appear to be malfunctioning. I'm wondering if the problems are related...   CAE