Blood Sweat and Gears
By Steve Blancard

Spring is just about here. For those residing in the colder regions that lay up their machines for the winter, it will soon be time to get the old iron out and give it a good once-over before hitting the road. Most of us know to check tire pressure, battery charge and fluid levels, but a few of the often overlooked areas include: checking tires for cracking or dry rot, pumping fresh grease through the fittings, oiling the linkages and checking wiring terminals for corrosion and tightness. Also important on dry sump motors is checking for excess oil in the sump. The oil feed check valves of many old machines tend to allow oil to leak by when sitting for prolonged periods. This results in excess oil accumulating in the sump that can make kicking over the motor difficult, cause a severe loss of power and clouds of blue smoke. At the worst, it can result in engine damage. So be sure to take a few extra minutes and check the sump for excess oil and drain if necessary.

Read on for a discussion of torque and horsepower, but get your abacus out first and be prepared to sling some beads; there is a little math involved.

A Primer on Horsepower and Torque
From the earliest days of practical self-propelled vehicles, makers compared the power of their machines to that of the horse. While it could be argued that other animals such as oxen, mules, donkeys or camels could be the reference, the horse has come down to us as the universally recognized standard of comparison. In the 18th Century, James Watt determined that the work in foot-pounds that a draft horse could perform in one minute was taken as a unit of power. This was calculated as 33,000 lbs of weight raised through a height of one foot in one minute or any of these factors which multiplied together equaled 33,000 foot pounds. Thus 33,000 foot pounds of work in one minute (or 550 foot pounds per second) equaled one horsepower. To understand horsepower, one must understand the definitions of torque, work and speed.

* Torque - is the product of work or force multiplied by the distance at which it is exerted from the center of rotation. When we say that an engine develops 50 foot pounds of torque, we mean that at a distance of one foot from the center of the crankshaft, the engine exerts a force of 50 pounds.

* Work - is a force acting through a distance. For example, if you lift 10 pounds through two feet, you accomplish an amount of work equal to 10 pounds x two feet or 20 foot pounds of work.

* Speed - This is the rate of speed doing the work. For example, suppose you lift 10 pounds through two feet in 10 minutes. The power is 10 pounds x two feet divided by 10 minutes or two foot pounds per minute.

Over the years horsepower has been calculated in a number of different ways. Motorcycle manufacturers were always looking to show their machines in the best light and horsepower ratings in advertising were a big selling point. In the late 19th Century one of the early methods was developed by the National Automobile Chamber of Commerce (NACC). This formula is based on piston speed. When the formula was first adopted, most engines developed their maximum horsepower at 1,000 feet of piston travel per minute. The formula was worked out using this speed and an assumed cylinder pressure of 90 pounds per square inch. The factor of piston speed takes in both the length of the piston stroke and speed of the crankshaft in revolutions per minute. The shorter the crank-throw, the quicker it can be turned; the longer the throw, the more piston travel per stroke. This formula was expressed as:

Horsepower = Bore diameter in inches squared, multiplied by the number of cylinders, divided by 2.5.

For example, a V-twin with a 3-1/8" bore would be calculated as:
3.125 x 3.125 = 9.76
9.76 x 2 (number of cylinders) = 19.52
19.52 / 2.5 = 7.8 NACC horsepower.

As engines improved and piston speed increased, this formula became inaccurate, resulting in horsepower estimates that were low.

Another form of horsepower measurement was RAC horsepower or taxable horsepower. This measurement was instituted by the Royal Automobile Club in Britain and used to denote the power of early 20th Century British cars and motorcycles. Taxable horsepower does not reflect developed horsepower; rather, it is a calculated figure based on the engine's bore size, number of cylinders, and a presumption of engine efficiency. As new engines were designed with ever-increasing efficiency, it was no longer a useful measure, but was kept in use by British regulations which used the rating for tax purposes.


Ace motorcycle engine dyno with an Ace Four under test. Evertt DeLong on the right and Arthur Lemon on the left. From the David Lemon collection.

Dynamometers
It was acknowledged that determining horsepower based on fixed values did not accurately rate horsepower. Soon after steam engines became practical, engineers began to experiment with machines that could measure actual engine power. These machines were known as dynamometers. One of the first dynamometers was developed by Gaspard de Prony who invented the de Prony brake in 1821. Froude Hofmann of Worcester, UK manufactured engines and vehicle dynamometers. They credit Willliam Froude with the invention of the hydraulic dynamometer in 1877 and say that the first commercial dynamometers were produced in 1881 by their predecessor company Heenan & Froude. In 1928, the German company Carl Schenck Eisengie�erei & Waagenfabrik built the first vehicle dynamometers for brake tests with the basic design of the today's vehicle test stands. Motorcycle manufactures soon adopted the dynamometer to their needs. Using a dynamometer, engine power could be measured in several different ways. It's important to understand that horsepower is not actually measured on a running engine. Torque is what is measured by a dynamometer, expressed in foot pounds. Then the actual horsepower is calculated by converting the twisting force of torque into the work units of horsepower.

Visualize a V-twin motor moving a 10 pound weight on a one foot long bar through one full revolution. If that weight is rotated for one full revolution against a one pound resistance, it has moved a total of 6.2832 feet (Pi multiplied by a two foot circle or 3.14 x 2 = 6.2832). Then to get the torque multiply 6.2832 x 10 which equals 62.832.

This can be expressed as:
Distance traveled (6.2832) x Force (10 pounds) = 62.832 Foot pounds of torque.
James Watt said that 33,000 foot pounds of work per minute was equivalent to one horsepower. So if we divide the 62.832 foot pounds of work per revolution into 33,000 foot pounds, we come up with 525.2. This is the engine RPM where one foot pound of torque is equal to 33,000 foot pounds per minute of work, and is the equivalent of one horsepower.

Here is where all this number crunching comes together. The formula to determine horsepower from torque is quite simple:

Torque x Engine speed / 5252 = Horsepower

Why is 5252 in the formula? Without going any deeper than necessary, suffice to say that it is a constant equaled to the RPM required to move a one pound weight one foot from the crankshaft. Regardless of the actual torque or speed of an engine, the 5252 figure remains a constant in the formula for horsepower.

So let's calculate our V-twin's horsepower. We know that this engine produces 62.832 foot pounds of torque at 525.2 RPM and that equals one horsepower. Let's say we want to determine the horsepower at 2,500 RPM. Using the horsepower formula above we have:
62.832 x 2,500 = 157080, divided by 5252 = 29.90 horsepower.
At 2,500 RPM, our V-twin develops 29.90 horsepower. By varying either the torque and/or the engine speed in the formula, horsepower can be determined across the full RPM range of a motor.

By now your head is probably swimming with numbers. But, hopefully, by understanding the relationship between torque and horsepower and how they were measured and calculated, you've got a better understanding of the forces at work within your engine.


Engines being tested at the Excelsior factory in Chicago, circa 1918. From the Bruce Linsday collection.

Improving Reproduction Springer Headlight Reflectors
From: Ronald Papasso

What I discovered is that the reproduction reflectors have the pins that hold the bulb in place oriented 180 degrees from a stock reflector. This upside down arrangement makes the high power filament (32 candle power) focus as the low beam and the lower power filament (21 candle power) focus as the high beam. My WLA (in civilian dress) has a reproduction headlight and I made this observation when I was taking load measurements on my bike. I found the low beam drew 1 amp more than the high beam. Given the high beam is supposed to be 32 candle power and the low beam is supposed to be 21 candle power, it did not make sense that the 32 candle power filament drew an amp less than the 21 candle power filament. Fortunately, I have an old stock headlight with a reflector and that's when I discovered the bulb's pins are 180 degrees different between the two. I also looked at a buddy's reproduction reflector and it was oriented the same as my reproduction reflector - both 180 degrees different from a stock reflector. As my research continued, I could spot a stock reflector from a reproduction reflector in a line up of old Harleys by looking at the pin orientation through the headlight glass, it's that consistent.

To correct this I notched the bottom of my headlight shell for the reflector tab and turned the reproduction reflector upside down. This now oriented the bulb the same as the stock reflector and the higher power 32 candle power filament now focuses as high beam and the lower power 21 candle power filament focuses as the low beam. I do occasionally ride at night and turning the reproduction reflector upside down to get the higher power filament focused as the high beam makes a big difference, literally like night and day when the high beam is on!

If you have access to a stock reflector and a reproduction reflector, take a look at the pins the bulb locks on to. The stock reflector has two pins at the top and one pin at the bottom. The reproduction reflectors have one pin at the top and two pins at the bottom, 180 degrees different from the stock reflector.

More on Leak Testing Brass Floats
From: Greg Fittro

When you toss the brass float from the freezer to the hot water to check for leaks, make sure it has a screw well seated in the mounting hole to seal the inside. This is critical for those of us who are slow on the uptake. Guess what? If no screw, then water gets inside the float.

At this point I unsoldered the weep hole in the float and began to dry it out. To aid drying the float I sat it on top of the kitchen bread toaster and then pushed the lever down, as if toast was inside (Toaster is set to put a medium toast surface on Wonder wheat bread). Note: watch toaster so it does not burn house down while consuming alcohol and watching sports on TV. The float gets up to 150-180 F, or so, and a couple shakes expels the water. Watch the finger tips or first degree burns result. Repeat several times as required to expel all water. To dry out the float even more I placed the float on the cast iron radiator that heats my home. My home's cast iron radiators stay below boiling. A gas forced air supply vent will work also. I left the float on the radiator overnight and resoldered the weep hole next day. Oh, don't forget to shake the float & make sure that all liquid is expelled from the float before soldering. Recheck the float setting before assembly to carb body.

More on Troubleshooting Electrical Gremlins
From Tom Sheahan

I have an addition to your "Troubleshooting Electrical Gremlins" comments. The main problem is thick paint or powder coating. Removing the paint in an area under the mounted piece may not be enough. To make up for the paint thickness, I'll coil thin solder wire in the shape of a disk. This coil should be large enough to cover the removed painted area. Apply electrical grease and place it in the removed painted area. Once the mount is tightened, the solder will flatten into the unpainted area and provide the ground connection. I have used this method on the generator mount, generator caps, and headlight mounts without any problems.

Correction
Several members contacted me after the Winter 2006 magazine came out and pointed out an error in my Troubleshooting Electrical Gremlins article. On page 68 I discussed how corrosion in a lighting circuit can create enough additional resistance to raise voltage well above the 6-8 volts that the bulb was designed for. The result - a blown bulb. This was incorrect. Voltage cannot rise above what is available from the battery. What I was thinking about, but did not convey properly, was that when corrosion develops in the battery ground connection, the generator voltage can increase because the added resistance in the ground circuit impedes return current flow to the battery. If the lights are turned on, a blown bulb may result because voltage exceeds the bulb's rating and current is forced through the bulb because it is the path of least resistance to ground. Sorry for the confusion, folks.

Disclaimer: If you regularly hurt yourself trying do-it-yourself projects, please don't try the projects outlined here...

The Antique Motorcycle Club of America, Inc.® accepts no liability for any loss, damage or claims occurring as a result of advice given in this publication.
That's all for now. Do you have a tip, trick or idea you'd like to share? Send it to me and I'll try to use them in a future issue. Steve Blancard, 311 Twin Lake Dr., Fredericksburg, Virginia 22401. Or by e-mail to my new e-mail address splitdorf@cox.net. Ride Safe.

© 2007 AMCA - this refers to all articles, photos and graphics!