A Brief Word
For seasoned collectors, and those who have been around engines for a long time, much of the following is probably old news. However, there are a lot of folks new to the hobby, and who are oftentimes daunted by the mechanism of an 'old engine.' Figure 1 shows the valves and rocker arm of a typical engine, in this case, it is a Stover.
Valve timing is an important part of getting an engine to run properly, and with wear the exhaust valve wears into the seat, thus getting 'longer' in relation to the rocker arm. Regrinding does the same thing. Usually, the cam design is such that the exhaust valve should just start to open about 10 degrees before outer dead center. This is so that the exhaust valve is pretty well open by the time the piston begins the exhaust stroke. When timed this way, the exhaust valve should close at about top dead center, or perhaps a few degrees past TDC.
When there are no timing marks (and there usually aren't), we just set the valve timing to where it looks about right and go from there. If the valve timing is too late, in other words if it begins to open too late, the engine runs hot, and doesn't sound right. Setting the timing too early, on the other hand, is no good either. The cam dwell is already built into the cam, and that can't be readily changed, so the best way is to begin with a setting of 10 to 15 degrees before outer dead center for the valve to open. It will be pretty obvious when the piston is on inner center what the builders had in mind.
Figure 2 shows the detent setting for a Stover Type K engine. In Figure 2, 'A' is the distance between the latch finger and the catch block with the engine at rest. Notice that for a 2 horsepower engine, this distance is only 5/32 of an inch. Adjusting this gap is important, since it changes the speed differential between being hooked up and dropping out to hit a shot. Oftentimes you will see an engine running at a show, and it slows way down before unlatching, and then has to hit several shots before it hooks up again. In many cases, this is because the gap between the latch finger and the catch block is too large.
Worn parts can create major problems with hit-and-miss governing. If the push rod is badly worn in its guides, it rarely stays in the same place all the time, and as it moves to different positions, the gap referred to above will change. Worn governor linkages can also cause all kinds of problems; there is little other way to remedy these without reaming out the parts and fitting with new pins.
Worn out cam rollers are always a headache. In many instances, we have cured the problem by finding a sealed ball bearing of the same o.d. as the roller, and then fitting up a new pin for the inside race.
If either the catch block or the finger are worn off or dull, the finger is likely to slip off the block. If these parts are hardened, sometimes they can be salvaged by careful grinding to restore good mating surfaces. The catch block and finger can usually be adjusted relative to each other. In most cases the catch block should travel past the finger just enough for the latter to release on its own. Too much gap between the finger and block in the lengthwise travel can also cause problems.
While these aren't all-inclusive answers to questions about valves and governing, they may be of help to some of the folks who have queried us.
Our first question this month is:
34/3/1 Unusual Engines
John A. Davidson, Box 4, 8250-200 Ave., Bristol, WI 53104 sends along a page from a 1912 catalog of Marshall-Wells Hardware Company of Seattle. It shows the Marswells 1? HP pumping engine, along with their 3? and 6 horsepower models. Old hardware catalogs often used notoriously poor paper, but nevertheless, we thought it worthwhile to reproduce the entire page, just in case someone might be able to identify the engines, particularly the very unusual 1? HP model. See the page, 'Gasoline Farm Engines.' We also received this page and a query from John J. Wohlfeil, 190 HCR 1, Marquette, MI 49855-9704. Apparently these two gentlemen were at the same auction! Thanks to both of you for sending along this information. Perhaps someone will be able to identify the engines.
34/3/2 Monitor Engine Q. What is the year built for a Monitor VJ engine, 1? HP, s/n 48727? Dale Russell, Route 4, Box 214E, Independence, KS 67101.
A. We don't have an exact date, but sometime after 1934.
34/3/3 Leader-Domestic Q. I have a 2 HP, single-cylinder Leader engine. It is s/n 4798 and is a Leader Domestic, made for Leader Iron Works, Decatur, Illinois, by Domestic Engine & Pump Co., Shippensburg, Pa. It has no spark plug, but is fired by an insulated Hot Point with a coil and battery, and runs perfect. Could anyone provide any information on this engine? Allan R. Dreger, 106 Marshall Cres., Winnipeg, Manitoba R3T 0R4, Canada.
34/3/4 Corliss Engine Q. See the photos of an 8 HP Corliss gas engine made between 1914 and 1916 by Corliss Gas Engine Company, San Francisco, California. Any information on this engine would be appreciated, including anything on the company, advertising, manuals, or the proper color. Bud Melvin, 266 E. 39th St., San Bernardino, CA 92404.