A little help or info please

[iambutch1]

I am working on a 72 Vette in which I have installed a gen 1 350 chevy perforance crate engine with vortec heads, ZZ4 roller cam and roller lifters. I have installed the dual quad vortec intake number 5426 and two performer series 500 cfm carbs item number 1404. I have everything set up except I am not sure how to set up the linkage between the two carbs. I know that they dont both kick at the same time but I cannot find anything that would put me in the right ballpark. Also will a stock engine driven fuel pump feed them properly or do I need to put in a electric pump.

The car has the body off of it which makes it easier to work with and would like to have as much as possible setup prior to placing the body back on.

Any help is greatly appreciated. Mike

 

[Hib Halverson]

With any street-driven dual quad set-up, you usually drive on the primaries of the primary carburator. As you step into the throttle, you get the primaries on the secondary carb, the secondaries on the primary carb and then, finally, the secondaries on the secondary carb.

If you purchased a linkage with the two Performer carburetors, the instructions should explain how to set that up. If you did not purchase a linkage, I suggest you buy Edelbrock's #7094 linkage assembly and set it up per its instructions.

As for your fuel pump question, it is likely you'll need additional fuel volume. You can get it with either a conversion to an electric pump or by going to an aftermarket, high-performance mechanical pump. That said, the best way to address a potential fuel flow problem is to do some testing with a fuel pressure gauge and the engine under load. If you see the fuel pressure dropping at high rpm at the top of third gear, you probably need more fuel flow and a better pump. On the other hand, if the fuel pressure stays in the range Edelbrock suggests for its carburetors, then you're ok with what you have now.

Lastly, be advised that, in my experience with the same carb set-up on a Big-Block, the Edelbrock AFB clones tend to flood under heavy braking. While I really liked the visual impact of the dual four-barrel carbs, I found a single Holley performed somewhat better and drove a lot better. Your results may differ.

 

[iambutch1]

Thank you for your help. I did buy the intake, carbs and linkage as a set from Summit racing and went through everything in the installiation guide and it said nothing of how to set up the linkage. I will probably go ahead and update to an eletric pump and put in a return line. The body is off of the car right now and I thought that whatever I do I will do it before replacing the body. Thanks again.
Mike

 

[1963SS]

Good luck with the linkage and good luck with 1000 CFM on a sbc. I believe that when you open the secondaries that it may lean out so much that it may bog down. I did a dual quad setup on a modified 440 Mopar and I used two 390 CFM's and they worked great.