CRG Discussion Forum

Camaro Research Group Discussion => Maintenance => Topic started by: sixt9x33rs on September 03, 2011, 10:24:58 PM

Title: No vacuum signal
Post by: sixt9x33rs on September 03, 2011, 10:24:58 PM
I have a 67 quadrajet on my 69 convertible. I have the stock vacuum lines attached to the distributor, I have no vacuum signal to the vacuum can on the distributor. I have the hose connected to the front port of the carb just like the original setup. Any idea why I don't have a signal here?

Thanks

Lawrence
Title: Re: No vacuum signal
Post by: JohnZ on September 04, 2011, 10:14:31 AM
Quote from: sixt9x33rs on September 03, 2011, 10:24:58 PM
I have a 67 quadrajet on my 69 convertible. I have the stock vacuum lines attached to the distributor, I have no vacuum signal to the vacuum can on the distributor. I have the hose connected to the front port of the carb just like the original setup. Any idea why I don't have a signal here?

Thanks

Lawrence

Most likely because that carb is designed for a "ported" vacuum connection; cap it off and look for a connection that provides full manifold vacuum at idle. If you can't find one on the carb, use the vacuum fitting on the intake behind the carb.
Title: Re: No vacuum signal
Post by: sixt9x33rs on September 04, 2011, 08:44:38 PM
John this must explain why the distributor was hooked up to a different portnbefore I started to work on it. I will go back to the other source.

BTW, what does "ported" vacuum mean vs manifold vacuum?
Title: Re: No vacuum signal
Post by: Gramps69Z on September 04, 2011, 09:19:03 PM
Quote from: sixt9x33rs on September 04, 2011, 08:44:38 PM
BTW, what does "ported" vacuum mean vs manifold vacuum?

With ported you are relying on the position of the throttle plates and with manifold it's constant.
Title: Re: No vacuum signal
Post by: JohnZ on September 05, 2011, 10:45:40 AM
<<BTW, what does "ported" vacuum mean vs manifold vacuum?>>


This will explain about ignition timing, advance systems, and full manifold-vs.-"ported" vacuum:

http://www.camaros.org/pdf/timing101.pdf
Title: Re: No vacuum signal
Post by: sixt9x33rs on September 06, 2011, 12:45:06 PM
Thank you