Model A
Ford Garage
Condenser Capacitance
Pictured above are a pair of NOS Ford A-12300 ignition condensers. These have the Ford script and the zinc can.
The August 15, 1928 detail drawing of condenser A-12300 on file at the Benson Ford Research Center does not specify the capacitance of the condenser, though it does list the suppliers. The drawing indicates the condenser to be either a Bosch CD-77949, or an Auto-Lite 1GF-2004.
Pictured below is an October 19, 1928 letter from the Ford Service Department in reply to a reporter's question about the rating of the Model A ignition condenser.
According to the Ford letter, the capacitance of the condenser is 0.3 Microfarads.
The condensers are tested at 540 volts DC, and at this voltage have a resistance of approximately 100 megaohms at 70 degrees F and average air humidity.
According to the Ford letter, the capacitance of the condenser is 0.3 Microfarads.
The condensers are tested at 540 volts DC, and at this voltage have a resistance of approximately 100 megaohms at 70 degrees F and average air humidity.
Also noted in the letter is the fact that the ignition coil has 250 turns of #20 enameled wire in 4 layers in the Primary winding, and that the Secondary winding has 16,000 turns of #38 enameled wire.
Subsequently, the May 29, 1930 detail drawing of condenser A-12300 on file at the Benson Ford Research Center specifies the capacitance of the condenser to be 0.20-0.25 Microfarads, which is lower than referenced in the earlier October 19, 1928 letter.
The May 29, 1930 detail drawing also indicates the condenser to be either a Bosch CD-77949, or an Auto-Lite 1GF-2004.
A word about Condensers:
It is generally not recommended (and may be unreliable) to use NOS or old condensers due to the technology used to produce them. Many of them are subject to failure due to perforation of the internal wax paper type insulator which separates the foil layers.
This risk of failure is compounded by the physical location of the condenser on a Model A. It is placed inside the cast iron distributor casting, just above the cylinder head, and in close proximity to the exhaust manifold.
The Model A condenser is in a high temperature environment with little air circulation or cooling. Virtually all other automotive condensers are placed up higher and away from engine heat.
It is generally not recommended (and may be unreliable) to use NOS or old condensers due to the technology used to produce them. Many of them are subject to failure due to perforation of the internal wax paper type insulator which separates the foil layers.
This risk of failure is compounded by the physical location of the condenser on a Model A. It is placed inside the cast iron distributor casting, just above the cylinder head, and in close proximity to the exhaust manifold.
The Model A condenser is in a high temperature environment with little air circulation or cooling. Virtually all other automotive condensers are placed up higher and away from engine heat.
To minimize the risk of condenser failure, it is generally held that the modern "burnout-proof" condensers of the proper capacitance are the most reliable.
These condensers have a modern polyester (Mylar) film internal insulator and are better able to withstand the high heat conditions found in the Model A application.
These condensers have a modern polyester (Mylar) film internal insulator and are better able to withstand the high heat conditions found in the Model A application.
More related information on Ford Garage:
- For more Model A & B related information, use the Site Search box at the top or bottom of this page.
- Model A & B Ignition Components Interchange Table
- Model A & B Condenser Details
- Model B & Model 46 Distributor Design Details
- Model B & Model 46 Distributor Advance Operation
- Model B & Model 46 Pertronix Ignitor Distributor Timing Procedures
- Model A Remund Pertronix Electronic Ignition Instructions
- Model A & B Engine Cam/Valve and Ignition/Spark Timing Discussion
- Model A, B, & Model 46 Camshaft Gear Timing Cover Differences
- Model A Distributor Lower Plate Wiring Solution
- Model A Nu-Rex Centrifugal Spark Advance Unit
January 2004