Improving the Intake System


As you can see from the diagram, the stock single carb setup did not work well for performance use. Multiple carbs on special manifolds gave better fuel distribution.

milti-carb intake manifold


If you couldn't afford a special intake from a speed shop, you could at least adjust the accelerator pump on the Ford carb. Moving the arm past the winter setting gave a larger pump shot. This increased gas consumption, but got you moving faster.

Ford accel pump

. . . you will see that two carburetors are recommended for a road job, three carburetors for really hot road jobs where gasoline mileage is not too important, and low speed torque is not given much consideration. Four carburetors should not be given any consideration unless planning to use them on an all-out competition engine. Even then we suggest that the best performance will be provided when the engine is run on methanol fuel.

Carburetor Combinations as given by Bill Fisher, 1952

Stromberg 97s with .046 main jets - rest of jets, etc. stock settings
Chandler-Groves - same

TRIPLE: Stromberg 97s or 48s on end carbs - Stromberg 81 in middle (gives smoother idle). Use stock jets throughout all carbs
Chandler-Groves same as for dual

FOUR: Use stock jets in Stromberg 97s or 81s. Experiment to get best settings

Chandler-Groves use .052 main jets, plug two of the four holes in economizer jet, otherwise stock settings.
Stromberg replacement 380272 use .043 mains, rest stock.

Same as for dual

Stock jets as for 1932-48

Lincoln V-8 Flathead
Stromberg replacement 380272 use .045 mains, rest stock.

Notes: If your dual carb installation gives a flat spot off the idle, try advancing the spark several degrees. If this does not help, then go one step richer on the main jets.

I think the Lincoln V-8 was also used in the big trucks of the era (F7 and F8, etc.). - ed

Here is some feedback from a visitor about carb options.

From: "kerry sisler"
Date: Sat, 8 Sep 2001 21:31:09 -0500
The section on boosting up power dealing with intakes seems to be lacking any discussion of one of the simpler and more productive upgrades, in that it doesn't require any significant twiddling and tuning to get working well;

Offy Aluminum 4bbl intake
Holley 390CFM with electric choke (I didn't want to overcarb the nearly stock engine)
1" carb spacer (only needed if the heads feed water at the center of the heads)
Over the counter 10" air filter setup.

The standard Ford carb link can be cut and spliced with a piece of tubing soldered over the cut to get it to the correct length and stock pedal feel.

The manifold has a flat at the drivers front side that is simple to drill for a PVC valve (either thread it for that kind of valve or use a grommet for the push in kind). Then run a hose back to the PVC port.

This lash up plus an electric fuel pump, a set of 1 5/8" dual exhaust with modern turbo mufflers in the stock locations, and a 40,000 volt J.C. Whitney chrome coil really woke up my fresh 59AB Merc engine setting in a '39 sedan. Turning the standard, unchanged '39 3-speed tranny and stock rear end (with later backing plates and drums) would light up the big P235 x 15 bias tires on Ford van wheels (painted black with JC Whitney baby moons and chrome trim rings, of course). It pulled hard all the way through the RPM range.

Back to the hot rod the flathead page.