Just wondering if this would be a good choice for my flathead. Also, what sort of mileage would I get??

 

Mileage is based much more on cam than carb. The carb relys on vacuum to create a pressure drop across the venturi in the carb. The pressure drop allows fuel to meter through the jets to provide the correct air / fuel ratio. If you are looking for a good carb the holley is a good one.
IF
1. all the vacuum lines are hooked up to the appropriate places.
2. no internal passages are plugged
3. the proper jets are installed
4. you have a carb that is not internally worn out (throtle plate shafts, accelerator pump bore etc).
I would think a 600 CFM rated carb would be plenty for a flathead.

 

A 390 cfm 4-bbl is about the biggest for a street flatty. If the carb has 1.5" primaries and vacuum operated secondaries, I wonder if the secondaries would ever open?!

 

Actually, I was trying to be funny. It is an absolute correct carburetor (Holley stamped Ford numbers on it at the factory in addition to their own list number) for a 1969 Shelby GT500. It is rated at 735 cfm, at home on a 428 CJ, probably a bit much for a flathead. I'm going to be restoring it over the next couple of days.

A better picture would show it has 1.625" venturis, both primary and secondary. You ought to see the size of the fuel pump I will be refinishing for it.

 

What is the cfm on a 94?

 

~175-180 ish, there is some variance.

 

So will putting dual carbs, or a 4 barrel on my flathead increase my horsepower if i do NOT mess with my cam?

 

You are going with headers and/or dual exhaust with your duals or 4V, correct?

 

Well its still a work in progress, but i will be running the stock manifolds, and running duals but at the moment just running the 2 barrel

 

Flat V8's are breathing-limited. The carb is just one part of the restriction. A good porting job on the block will help. The exhaust will help. But for street use, don't expect miracles, it's only 239 c.i. with 6.8:1 compression. The 4-bbl is less trouble with linkages and probably better mileage (running on primaries most of the time). Duals have undeniable cool factor, tho.

 

So if I have 100 horse now how much will duals and a 4 barrel gain me on horsepower?

 

With no other changes? 10 HP at the most, IMO. You'd be limited by the stock ignition, low compression, the stock exh manifolds...You'd undoubtedly boost the bottom end noticeably, and that's where flatties excel anyway. I'd be interested what other flathead folks think...

PS -- most "100 HP" (8BA) flatheads make about 80 - 85 HP in real terms (dyno)

 

Well, my engine is not rebuilt, but it had a valve job recently so it should be close to those numbers, but i thought that if i let it breathe it would do it some good.

 

It would be noticeable, but you wouldn't get the full benefit without other pieces -- high compression heads or a stroker crank/pistons, cam, headers... or just bolt on a blower!

 

Could get yourself some EAB (52-53 Ford car) heads for a bump in compression. With dual deuces, you will need a different distributor, such as a modified chebby. The stock Load o matic may not get the vac. signal from twice the carbs. I can't speak as to how the stocker works with a 4V.