Model A & B & V8
Ford Garage
Spark and Throttle Control Rods
Did you ever notice that Model A spark and accelerator-to-carburetor control rods always seems to be too long or too short, and that different reproductions are different lengths?
The reason is actually pretty simple!
Ford had numerous similar-but-different linkage control rods for a variety of applications from 1928 through the mid 1930s.
Are you using the right ones?
The following table shows the various linkage rods in order of increasing overall length dimension (OAL) of the rod itself, and also shows the virtual ball-center-to-ball-center dimensions of the various rods.
| Part Number | Description | 'A' Dimension Center-to-Center Rod Only |
'B' Dimension Overall Length Rod Only |
|---|---|---|---|
| A-9742-A | LHD Accelerator-to-Steering Column, 1928-31 RHD Spark Advance |
5-7/8 | 5-21/32 |
| A-9742-B | LHD Accelerator-to-Steering Column Victoria Coupe and Deluxe Phaeton, 1930-31 (serviced by A-9742-A) |
||
| AF-9757 | RHD Spark Advance Deluxe Phaeton, 1930-31 (serviced by A-9742-A) |
6-1/2 | 6-9/32 |
| BB-9740-B | Accelerator-to-Carburetor 1933-34 4 cylinder |
8-29/32 | 8-11/16 |
| B-9740 | Accelerator Pedal-to-Throttle 1932 4 cylinder |
9-7/8 | 9-21/32 |
| 46F-9740 | RHD Accelerator-to-Carburetor 1933-34 V8 |
10-17/32 | 10-5/16 |
| A-9747 | Accelerator-to-Carburetor, 1928-31 | 10-5/8 | 10-13/32 |
| AF-9747 | RHD Accelerator-to-Carburetor Deluxe Phaeton, 1930-31 (3/7/32 drawing) |
11-1/8 | 10-29/32 |
| 18-9747 | Accelerator-to-Carburetor 1932-34 V8, BB-V8, 46-V8, 46-4 (renumbered AF-9747?) |
11-1/8 | 10-29/32 |
| 40-9747 | Accelerator-to-Carburetor 1933-34 40-4, 40-V8, 46-4 |
||
| 46-9740 | Accelerator Pedal-to-Throttle 1933-34 4 cylinder Commercial |
11-1/4 | 11-1/32 |
| AF-9747 | RHD Accelerator-to-Carburetor Victoria Coupe and Deluxe Phaeton, 1930-31 (12/23/37 drawing) |
11-29/32 | 11-1/2 |
| BB-9740-AR | Accelerator Pedal-to-Throttle 1932 4 cylinder |
13-5/16 | 13-3/32 |
| BF-9740 | RHD Accelerator Pedal-to-Throttle | ||
| A-9757 | LHD Spark Advance 1928-31 |
17-5/32 | 16-15/16 |
All of the above information was researched from original Ford detail drawings and releases at the Benson Ford Research Center, as well as various Ford Parts Price Lists.
An additional important consideration is that the steering column tube on all Ford and Gemmer two-tooth Model A steering gears is (mis)adjustable.
Make sure the quadrant orientation of the column is not limiting the intended travel and function of the spark and throttle hand levers!
It is important to loosen the tube clamp at the base of the column tube and rotate the tube for adjustment, in order that the full range of motion of the distributor points advance plate can be achieved when operating the spark advance lever at the column quadrant.
Tighten the column clamp after confirming that the quadrant advance lever and control rod achieves the full range of travel of the distributor plate arm in its bakelite body notch.
Next check the operation and travel of the hand throttle lever at the quadrant, and its effect at the carburetor throttle.
Do not allow the hand throttle quadrant lever operation to prevent the carburetor throttle lever from resting on its idle-stop screw.
Bend the 'output' arm of the throttle control assembly (accelerator/foot control assembly) as needed to adjust for the full range of travel of the carburetor throttle lever.
Wow!
Now you can correctly retard the spark for timing and starting, advance the spark for running, as well as achieve the full range of motion of the throttle lever on the carb!
Now you can go faster than your previous 'personal best' of 41 mph!
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April 2004