[thor]

How much horsepower could I expect to gain by going from 1 750cfm carb to two 600cfm carbs, assuming that's all I change? I have a basically stock built 440 Magnum with electronic ignition, 10-1 compresssion, Schumacher headers, Edelbrock performer RPM intake and 750cfm Edelbrock carb. I also use an electric fan setup, instead of the belt driven one. My tax refund is coming and I would like to spend it on my Challenger.

[Follicly Challenged]

I'll assume you're going to a dual quad intake also ? Which one ? If it's a single plane, the HP gain ain't gonna be worth the bottom end characteristic power loss.

[dave-r]

The dual plane don't add any power either. In fact it will probable loose power.

Read my bit about horsepower theory. Carbs do not make power. Heads and cams make power.

[dave-r]

Hell. It was 2am here when I replied to that this morning. I am suprised I could write at all......

OK carbs. Let me expand on this.

A carb lets air and fuel into and engine. The more air and fuel the engine burns the more power you make.

But it is the engine that draws the air/fuel in. So no matter how big or how many the carbs the engine will still only draw in the same amount of air and fuel. Obviously rpm is a factor. The higher the rpm the more carb you need.

The only time you will make more power with more/bigger carbs is if your current 750cfm carb is too small for your engine at high rpm.

However since you say your engine is near stock and probably has a stock or near stock cam I am sure the 750cfm carb will be the ideal size.

You also need to think about the intake manifold. Dual carb manifolds tend not to distribute the air/fuel to all the cylinders very well. Nor do they flow very well.
The manifold you now have is a very good one. It will work well at low rpm and up to 6500rpm. Being a dual plane it will also have quite good throttle response.

So the bottom line is leave the carb and intake alone.

[Christer]

Dual carb manifolds tend not to distribute the air/fuel to all the cylinders very well. Nor do they flow very well.

Really? How come? (It is mostly the last sentence I am thinking about)

[thor]

Should I go with aluminun Edelbrock heads and keep the carb/intake setup as is?

[dave-r]

Thor. Yes if you want the heads they work well with the intake/carb you have.

Christer. Sorry mate. Missed your post somehow. The progressive way the carbs open coupled with the way wedge engines have their intake ports does not make for good mixture distribution except at WOT.

On top of that the manifolds just do not flow that well at higher rpms. Something to do with the way a basically stock casting has been altered to take two carbs.

A cross ram works well though. A tunnel ram works too but only at high rpm.