Notes and Responses From Readers
Remarkably, yet another Crown engine has surfaced since Doug Nash wrote about the Crown Motor Works in the April 2002 GEM. Jamie Coobatis, 34730 Seven Mile Road, Livonia MI 48152-4032, called in to tell us he has a 1/2 HP Crown that, until recently, he thought was an Elgin. Jamie sent us some pictures of his Crown, along with the following e-mail:
'I purchased this engine from my cousin about six years ago. He bought it at an engine swap meet in Cool Springs, Pa. He was with a buddy of his and he told me he had to borrow some cash from his buddy to buy it. His friend wasn't interested in it because he said he already had one! That's how it came to be named an Elgin Comet. He then sold it to me as a Comet.'
Jamie also contacted Doug Nash, and here's what Doug had to say about the photos of Jamie's engine:
'They clearly confirm that you have a genuine Crown 1/2 HP motor. It looks like its flywheel, fan, carburetor, ignition timer and engine castings (including base) are all original. I can't vouch for the originality of the muffler, air-intake filter and fuel tank (all made from brass); in fact I think they are not original since my Gramp's surviving literature doesn't mention anything other than iron for those components. The oiler on the side of the cylinder and the grease cup on the side of the crankcase are most likely original, since the original literature mentions them. The spark plug is the correct vintage and could be original. As to the all red color of your engine, I doubt that is original since Gramp was an extremely modest and very conservative person and would never have painted anything bright red. Remember, he was a contemporary of Henry Ford, who supposedly told buyers they could buy his cars in any color they liked, as long as it was black!'
Talking with Jamie, it turns out the gas tank is not original and was in fact made from an old fire extinguisher. But, Jamie clearly has a Crown engine, and he thinks he might know of yet another that, like his, was thought to be an Elgin Comet. Stay tuned, the hunt for surviving Crown engines is far from over. -Editor
I enjoyed your excellent article on ignition systems in the October 2002 edition, and I thought some additional theory would be helpful, especially to explain the purpose of that mysterious capacitor (or condenser) that is always wired across the ignition points.
When the points close, the current through the coil ramps up until it reaches a constant value (usually several amps), which is determined by the resistance of the coil primary. When the points open, the energy that has been stored in the magnetic field of the coil flows into the capacitor, which charges to a voltage several times higher then the original battery voltage. The current then reverses and the energy flows back into the coil. This oscillation, called 'ringing,' produces an AC voltage across the coil primary that may reach 75-200 volts.
The secondary winding of the coil has a large number of turns compared to the primary. The secondary multiplies this AC voltage several hundred times and provides the 20-30,000 volts that initiate the arc at the spark plug. The purpose of the capacitor is to form a resonant 'tank' circuit that produces a burst of AC voltage that is much higher than the battery voltage and has a relatively long duration. This voltage is, in turn, multiplied a second time by the coil turns ratio and then fires the plug. If the capacitor is not present, the energy stored in the coil is instantly transferred to the plug, and the resulting spark is extremely short and ineffective for ignition.
Project Update: In case anyone doubted whether Chester Leighton's 'Mini McCormick' could pull its own weight, Chester sent this photo of his creation plowing his daughter's garden. Chester wrote about the IHC LA-powered tractor in the September GEM.
This double step-up explains why it is a good idea to replace the capacitor when changing points. The capacitor can appear okay when checked for shorts with a multi-meter, but it may break down at 100 volts or so. It also explains why an ignition system can act up in damp weather even when the spark plug and its wires are dry. Moisture is not a problem at 6 or 12 volts, but since 75-200 appears across the points, moisture in the coil primary circuit can sometimes provide a resistive path that will permit enough leakage current to reduce the spark output.
Larry Sears 45006 Mather Lane Hunting Valley, OH 44022 E-mail: firstname.lastname@example.org
GEM reader David Newman is looking for a home for a 1933 De Laval steam turbine that's been helping supply power since 1952 at a paper mill in the Philadelphia, Pa., area.
David says a local trade school has expressed interest in the unit, but he wants to see the turbine go to a museum or an organization that will set it up for display. He's not interested in seeing it go to a private collection.
It's situated under a crane way, and it can be split into three parts and loaded onto a flatbed in the building where it currently sits.
If interested, contact David Newman via e-mail at: email@example.com
Send letters to: Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265, or e-mail: firstname.lastname@example.org