From buick-rover-v8-owner@autox.team.net Wed Mar 22 16:03:32 2006 From: David Kernberger To: Barrie Robinson Date: Wed, 22 Mar 2006 15:04:25 -0800 Subject: Re: Carb to dizzy hook up Barrie et al, If there is a vacuum advance mechanism unit on the distributor and your driving is mostly normal on the road activity, then connecting it up is an advantage in my estimation. The idea is to cause earlier (more advanced) timing at part throttle conditions and thereby improve fuel economy. As the throttle is opened wider, manifold vacuum drops and the advance falls back to only what the centrifugal mechanism provides and this is in relation to engine speed only and has nothing at all to do with throttle position. Under heavy throttle conditions, if all the advance from both mechanisms was in effect, there could be a tendency to detonation and pinging and possible engine damage. This is why all out racing engines never use vacuum advance at all. The connection to the carburetor needs to be to the correct point on the base. I am not familiar with the carb in question but it is not correct to go directly to the intake manifold. The port you want is in the throttle body in such a position that it is shielded from the manifold by the throttle butterflies at idle and progressively becomes more exposed to the manifold as the throttle plates open. This produces very little vacuum at idle, a lot at most part throttle conditions and nearly none at full throttle. You need to use vacuum hose. It is, as you say, more suck resistant and does not collapse from the suction. Therre is my 2 cents worth. Cheers, Dave Kernberger ---------------------------------------------------- I have an Edelbrock 1404, manual choke, and a standard Rover V8 >distributor with Pertronix on my Rover 3.5L V8. There is no vacuum >connection between the two and as I did not do the motor bit I now wonder >how this effects things. Can anyone help in this domain? If I do need >such a connection is ordinary rubber tube suitable or do I need something >with more suck resistance? Please accept, in advance, my many thanks. > >Regards > >Barrie Robinson /// /// buick-rover-v8@autox.team.net mailing list ///