Gas Engine Blogs >

Field Notes

Wooden Aermotor Engine Base



After reading the August/September 2018 issue, I have to comment about the "Patent Page" section. Aermotor did in fact produce an engine with the wooden base as in the patent that you highlighted. I've attached a picture from a 1911 ad. I don't think they built that engine for very long, maybe only a year or two.

Charles Wise

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

Regarding Paint on Old Machinery

Photo courtesy of John Burgoyne

Like most engine or tractor rebuilders, there comes that inevitable time when that freshly rebuilt piece of old machinery has to be painted, a task few of us are qualified for and even fewer enjoy doing! Having rebuilt engines and machine tools for over 40 years, I would like to share my experiences and observations with the readers of GEM.

Over the years, I have seen a lot of over-restored engines and tractors, usually with the use of modern automotive finishes. While such finishes are very durable, they tend to be far too glossy and simply look out of place. Early equipment was painted with conventional oil-based enamels, usually applied with a brush and smaller parts being dipped. One difficult decision usually involves which parts to paint and which to leave bare. Nuts, bolts and valve springs are a difficult decision, although I believe most original manufacturers tended to paint everything that didn’t move (and some that did!).

One interesting thing I have noticed is that most old equipment did not appear to use a primer.

I have tried most of the popular store brands of enamel, but early in the game I settled on Valspar, mainly because they offered most of the popular engine and tractor colors. At first I wasn’t too enthusiastic about Valspar because of its very slow drying time, but as time passed I began to realize that a slower drying paint was also tougher and more chip resistant than a fast-dry paint.

I always use a primer and I believe that using the same brand is probably best. The top coat needs to be applied reasonably quickly after the primer has been applied, usually within 24 hours, to ensure good bonding and adhesion. Many of us fall into the trap of using an aerosol spray can to prime smaller pieces to prevent them rusting while we wait for larger parts to be prepared. Big mistake!

Aerosol primers use a different solvent that generally makes them incompatible with an oil-based top coat, so good bonding will not occur. Again, use the same brand and type of primer as your top coat.

When applying paint, I prefer to use a good quality brush, which allows the user to apply the enamel at full strength. Rough castings certainly benefit from brush painting, a good finish accomplished by applying an extra coat of primer followed by some sanding prior to the top coat.

While I advocate using a brush, there are times when spray painting is necessary. Conventional air-type guns can be problematic. First, the paint must be thinned with solvent to spray. This requires multiple layers of very thin coats, which tend to run easily. Secondly, a thinned enamel produces an unbelievable amount of “fog” or overspray, which will paint your lungs and everything else in your shop area, meaning you must use some sort of breathing apparatus and work in a clean space. Another type of paint gun is the HVLP (high volume, low pressure), but quality commercial versions are expensive and unwieldy.

At a local store that sells Chinese tools and goods, I found what looked like a gravity feed paint gun that claimed to be HVLP for under $20, and I found this product to be very satisfactory. I was painting flywheels on my 6 hp Sharples, which are about 4 feet in diameter, a job that would have taken many hours with a brush, but was accomplished in about an hour without the need for multiple coats. It will spray paint without thinning and produces considerably less overspray, and the finish was quite satisfactory.

The last, and perhaps the most important piece of information that I want to pass on to our readers concerns the shelf life of oil-based paints. I have checked with several manufacturers, who have all confirmed that oil-based enamel has a shelf life of approximately two years. Cans are supposed to be date coded, but that code is often difficult to decipher. To make matters worse, most paint stores are not aware of shelf life issues and cannot interpret the coding.

I recently experienced a painting disaster involving out of date paint. I had an unopened quart can of primer that had been in my stock for at least five or six years. When I applied the primer it didn’t dry, so I “forced” it to dry by leaving it in the 100 degrees Fahrenheit Texas sunshine for several days. When the top coat was applied, I found that I had almost zero adhesion, although I’m sure it didn’t help that the top coat was also probably out of date. This fiasco occurred with a pair of very large flywheels that then required professional (read: expensive) sandblasting to remove all the bad paint. I was not a happy camper.

Back to the subject of Valspar industrial and agricultural paint, it has become difficult to find. I used to be able to buy it at Tractor Supply, but they no longer carry it. Lowe’s hardware stores are supposed to be the stocking distributor, but I find that they only carry the home improvement products. Occasionally, it can be found in smaller hardware stores, but shelf life becomes an issue. Maybe a reader can enlighten me on this subject. I would welcome any input on the subject of painting and I’m sure that GEM would publish any info that readers would like to submit.

John Burgoyne
(817) 401-0320

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

Response to Thread Standards Concerns

Regular contributor Andrew Mackey responds to John Burgoyne (53/3/1: Thread standards) in the April/May 2018 Gas Engine Magazine. Andrew writes:


The studs and nuts on the Oil city-south Penn half-breed engine restored by Andrew Mackey. As with much old equipment, they were non-standard.

Photo by Andrew Mackey

I too have run into problems with inconsistencies in threading. When I restored my Charter-Mietz, the threads on the fuel pump, injector, as well as other connections were tapered pipe fittings. Although the OD of the fittings was the same as NPT US pipe, the threads were definitely not the same. They had the same threads per inch, but the taper was very different. The fittings seemed to be 1/4 inch. “Normal” 1/4-inch pipe in NPT has a thread length of approximately 1/2 inch to 3/8 inch. The fittings on the C/M engine were about 3/4 inch to 7/8 inch long, and the taper on the threads made their angle much less than that of NPT. Although the pipe OD was the same, neither the receivers on the engine nor the NPT fittings would interchange. A machinist friend cut new custom threads onto my NPT fittings.

Another time, I was on a plumbing job in a building destroyed in an explosion. We had to replace nearly 2 miles of 316 1-inch NPT stainless steel process piping that was damaged. We got the pipe and fittings from all over the country. The fittings (thousands of them) were shipped by the crateful. There were two crates that we had problems with. One had 90-degree elbows made in Malaysia. Our threaded NPT piping would not seat in the fittings. The pipe would thread into the fittings to the point where they bottomed out at the back of the elbow and would not make up at all. At first, we thought we had a bad set of dies or that the adjustable die was misset, but we were wrong. We then tried some factory-made NPT nipples, and they did the same thing. The nipples too, buried themselves completely, not making up at all. The socket threading in the elbows was cut too deep.

Another crate had fittings made in Taiwan. I do not know what their thread source was, but it was totally different from NPT. The thread count was similar to 3/8-inch NPT, and the internal diameter was smaller. You could not even start the NPT pipe into the fittings. We ended up tossing all the “bad” fittings on the scrap pile. The supply houses didn’t want them back, as they were unusable.

Another time, I ran into issues with the restoration of my engine club’s Oil City-South Penn half breed oil field engine. The main bearing mounting studs only fit in the holes where they had been removed from, and the nuts only fit the studs they also came from. I detailed this when I wrote the article for GEM, but didn’t realize there was another issue, as well. Two years later, we had to remove the cross head guides to replace some collapsed paper shims. We re-used the original shims during the original restoration, and now they had to be replaced. During the original disassembly, the studs and nuts were thrown into a box, then reinstalled. This time, when we went to replace the studs – you guessed it, they wouldn’t go. I guess we got lucky the first time. It took over half an hour, trying different holes and nuts on the studs, to get the studs and nuts back in their proper relationship. What a pain!

As the original steam engine had been built about 1880 or so, it probably would not have had standardization of threading as an engine would have today. The cylinder and head mounting were standardized, having been made about 25 years after the original steam engine. By then standardization was becoming the norm, so there were no issues with their reassembly.

Here is some good advice for the readers of GEM: When you disassemble an engine or piece of machinery, keep the studs, nuts and bolts together as a set. Mark and/or note where each stud or bolt came from during the process of removal, and make a drawing so they can be reinstalled in the same hole they came from. Don’t make our mistake and just throw them into a box. Make a note of which hole a stud or bolt came from, and you will save yourself a lot of hassle in the rebuilding process.

Andrew K. Mackey
(862) 432-1552

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

Single-Cylinder Beilfuss Automobile Engine

Single-Cylinder Beilfuss Automobile Engine

David Pfaff, who works with the non-profit R.E. Olds Transportation Museum in Lansing, Michigan, sent in some photos and information about the The Beilfuss Motor Co., Lansing, Michigan, which made a number of interesting engines, including horizontal singles and opposed twins. David writes:

The Beilfuss Motor Co., organized by Richard A.F. Beilfuss, was incorporated on June 4, 1902, with capitalization of $15,000. It was located at the corner of Saginaw Street and the Michigan Central Railroad (701 East Saginaw) in Lansing, Michigan. MotorWay reported in 1902 that Beilfuss would build gasoline engines for automobiles, in addition to the stationary type. Their initial offering was a single-cylinder, horizontal unit that developed 8 hp at 750rpm for automotive application, with a weight of 350 pounds. It featured a sideshaft valve train, gear-driven from the end of the crankshaft. The intake valve was of the atmospheric style.

Single-Cylinder Beilfuss Automobile Engine

Their stationary engine, a vertical design, was reportedly made in 2 hp to 7 hp outputs. In 1905, Beilfuss announced the availability of a new 16 hp, 2-cylinder, opposed-style automobile engine with a weight of 300 pounds. It featured a 5-inch bore and stroke. A 1908 advertisement in Gas Power featured a 2-cylinder opposed stationary engine producing 13-15 hp with a weight of 560 pounds, touted for stationary, portable, electric and general use. A notice in PowerBoating promoted the Beilfuss marine engine.

In 1910, Beilfuss advertised their 2-cylinder automobile engine, either air cooled with 10-12 hp or water cooled with a choice of 10-12 hp or 18-20 hp. The Beilfuss automobile engine was promoted as an original equipment unit for builders of “assembled” automobiles and as a replacement for worn-out engines in existing autos. The company was in business through 1912.

A single-cylinder Beilfuss automobile engine was recently donated to The R.E. Olds Transportation Museum. This engine is from the automotive collection of Don and Ken McDowell, well-known collectors of all things automotive, especially Lansing related. The engine was mounted in their 1899 Oldsmobile electric when they acquired it 1959, the sole survivor of R.E. Olds’ early foray into battery-powered vehicles. An early attempt had been made to convert it from battery to gasoline power. The conversion was never completed, and the vehicle has recently been converted back to its original electrical configuration and is currently on display in the museum.

The engine has been cosmetically restored and mounted on a display stand along with the planetary transmission that was found with the engine. The engine turns over readily, and perhaps has never been run. The exhaust valve train is missing. The intake is atmospheric. Our thanks go to Ken McDowell for his generous donation of this rare piece of Lansing industrial history along with his continuing loan of the 1899 Oldsmobile.

David Pfaff
R.E. Olds Transportation Museum
240 Museum Dr.
Lansing, MI 48933

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

Making New Valve Springs

new valve springs new valve springs new valve springs

Faced with replacing two broken valve springs on an ancient 4-cylinder engine, I found springs of the correct diameter and correct wire size. The stock spring was longer and stronger, so I gambled on some homegrown metallurgy. The replacement springs were fully compressed with bolts and washers, then cooked in a gas grill on the highest flame for three hours with the cover closed, then allowed to slowly cool in the grill. The resulting springs had a reduced spring rate of 40lb/in, matching the original spring, and matching height. Poor man’s metallurgy!

Leon Ridenour

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

Scale Gas Engines and Conveyer


Reader M. Moyers writes in, sending photos of some of his scale gas engines and a conveyor he built to make loading and unloading them for shows easier. We think the conveyor is a neat trick, and love the cam-stopper Callahan. “The flyballs disengage the camshaft when the engine is up to speed. The camshaft is timed to stop with the exhaust open. It’s a good runner,” Moyer writes. 
As to the conveyor, he says, “I built the conveyor to make it easier to load and unload engines. I don’t need to get into the truck with each engine; the engines are the last to go on the display and the first to be removed when the show is over.”


M. Moyers
37301 28th Ave. So., Unit 31
Federal Way, WA 92003

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

Thread Standards Concerns


Restorers of old engines and machinery inevitably run into problems involving thread or fastener standards, the most common being the 1/2-12 UNC standard that appears to have been used before World War I. I have not seen this standard on anything built after about 1918, when it changed to 1/2-13 UNC. In the British Whitworth threads, the 1/2-12 BSW continued until Whitworth was effectively abandoned in favor of metric in the early 1970s. Yet even standard sizes can vary slightly, which leads me to assume that many early manufacturers made their own taps and dies and didn’t always adhere to national standards. In addition to thread standards being “loose,” I have come across nuts or bolt heads with unusual hex sizes, sometimes made to the nearest 1/32 inch.

A frustrating thread-related problem recently occurred restoring a 4 hp Excelsior engine, where I found that all the tapered pipe threads used on the fuel tank, fuel pump, mixer and return circuit were oversized. The threads on a modern fitting bottomed out before they mated up. Clearly, Excelsior made their own taps and chose to make them about 1/32 inch oversized!

To overcome this, I purchased a taper turning attachment for my Hardinge lathe in order to custom make the oversized tapered pipe fittings. This attachment has since come in very handy for producing British Standard Pipe threads. Anyone owning or contemplating owning an English engine will find the common use of BSP threads. In every case the Whitworth thread angle is 55 degrees and in almost every case there is a different number of threads per inch. The basic pipe size and taper are the same, which means you cannot visually tell the difference between NPT and BSP. Don’t make the mistake of thinking a few extra turns of Teflon tape will fix the problem!

NPT and BSP are the only two tapered pipe thread standards in the world. Modern machinery uses one of the two, and you might be surprised to know that machinery (CNC lathes, milling machines, etc.) made in Taiwan or Japan is quite likely to have BSP threads used on the various hydraulic components.

I have experienced some real disasters that occurred at the port of entry where accessories are added before shipment to the end customer. Unfortunately, there is no color coding or distinguishable marks to alert technicians to the lack of interchangeability, and the inevitable happens. I never cease to be surprised at the number of “experienced” engineers and technicians who believe there is a metric pipe thread system or that BSP is metric: neither is true.

Perhaps the most shocking aspect of lack of standardization occurs in the metric thread system. While metric threads don’t show up often in engine restoration, they are out there. I came across two instances of standardization lapses recently. The first showed up when I tapped a metric M-10 x 1.0 hole in a model engine to accept an NGK CM-6 spark plug. The plug was so loose I dared not get it more than finger tight. When I measured the pitch diameter of the threads I discovered that they were 0.006-0.008 inch (0.2mm) undersized.

More recently, I made an adapter to install a modern NGK glow plug into an early Ruston & Hornsby open-crank diesel engine. The published size of the glow plug was M-10 x 1.25 and I ran into the almost identical problem after tapping with an ISO standard tap; the plug fit so loose I couldn’t risk using it. Again, the threads checked out at 0.008 inch (0.2mm) undersized. I sent an email to NGK outlining this problem, but have not received a response.

Having been an engineer and a journeyman machinist for over 60 years (I trained at Rolls Royce’s aircraft engine pision) I have certainly seen my share of peculiar thread problems. Many younger engineers are convinced the metric system is the ultimate in standardization, but as an “old timer” I know that the Whitworth thread standards (no longer used) and the American Unified screw thread systems are the two most standardized in the world, and this results in absolute interchangeability within their respective systems, something that does not happen with metric threads.

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email