Carb Questions

[art38]

I'm running two Edelbrock 1405's carb on a Offy high rise intake on my 409. Is it correct to connect my power brake vacuum and pcv to the rear of the rear carb, and the vacuum adv to the pass. side port on the rear carb. Do I need to connect anything to the front carb? Also is it bad run the carb as a progressive setup, another words rear carb active before front? I heard stuff about starving the two front cylinders, is this true.
I'm also setting up the carb with 95 primary jets, 70/47 rods, and 86 secondary jets.
Art38

[jim_ss409]

Yes, assuming the Edelbrocks are the same as the original Carters, I think they are. I would hook everything, including the vacuum advance to the port at the rear of the back carb. Or you could use the same port on the front carb if you want. Either way you should have manifold vacuum. I think the side port will be ported vacuum, meaning there won't be any vacuum at an idle. The reason to use manifold vacuum for the distributor advance is that it will improve your idle. The only time you'd want to use ported vacuum is when your vacuum canister in the dist. is too strong, this can cause surging. A Crane adjustable can will solve that. If you set the timing with the vacuum disconected and then hook it up to manifold vacuum the engine will rev up and smoothen out immediately due to the increased timing advance. Here's a link to a posting on a site that explains it perfectly. Scroll down untill you reach a posting by JohnZ http://www.camaros.net/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=4;t=006587
The factory dual quads used a progressive linkage but the Offy carbs are farther apart so the primary ports on the rear carb are a bit farther away. But I still don't think it would be a problem because even if the front cylinders ran a bit lean that would only happen during low load conditions. As soon as you give it much throttle the front carb would also open. By the way I always crack the throttle of the front carb about 1 1/2 turns so that it is also helping out with the idle. Then I do the rest of the idle speed adjustments from the rear carb. That seems to work the best for me.

[art38]

Thanks, Jim. This should be the weekend to crank it up for the first time.
Art38