Hi Guys, I need some help. I am installing a Holley 4175 on my 75 Grandville with a 400 motor. What vacuum source does the transmission use? Can I use the vacuum advance source? Brake booster source? Nothing is shown for connecting an auto transmission on the carb. I tried connecting it to a connector that was in the same general location as the old connection on the Qjet. Transmission now does not shift correctly. That port is called "purge". Whatever that is. What do I connect the transmission vacuum line too??? Thanks.
You'll want to connect to a manifold vacuum source (not ported). Usually the T off the back of the carb will do fine or off a port on the base of the carb.
Thanks. I have ports I can tap into right on the manifold. My vacuum advance and pcv valve come from the manifold directly. I also have another port with 3 taps on the manifold that are unused. Is my vacuum advance source just manifold vacuum? I have always seen VA and PCV comming from the carb not the mainfold. Thanks again.
Thanks. I have ports I can tap into right on the manifold. Is my vacuum advance source just manifold vacuum? Thanks again.
David
1. That will work 2. I wouldnt know. Some folks use ported some manifold for vac advance. If you check the port it's plugged into now with a vacuum gauge and have 0 vac at idle and then get a vac reading while revving it up to 2000 rpm, that would indicate a ported connection.
