The Indian Four began in 1927 when Indian purchased the Ace company. In fact for the first year or so the bike was called the "Indian Ace". (The Ace itself had been developed by the same engineer, one Will Henderson, who had designed the Henderson four. W
hen Henderson was bought out by the Schwinn Excelsior company he left it and in 1919 started the Ace company, building a very similar inline four cylinder engine bike which was bought out by Indian in 1927. The Henderson Four died in 1931 and the Indian Four in 1942. The only engine difference between the early Indian and Ace Fours was that the Indian had five instead of three main bearings. Over the years the sheet metal on the Indian grew more massive. A note on internal combustion engine terminology:
Indian Classic Motorcycles Flatheads are also known as L heads or side-valve. (Overhead valves or OHV is actually a misnomer, best term is "valve-in-head".) Prior to 1936 the Four had an F head design (also used in Jeeps a few years later I believe). The exhaust valves were below the head and off to the side as in any old flathead design but the inlet valves were in the head as in later OHV designs. Unique in autmotive history, in 1936 and 1937 only, the F head was reversed. This "upside down" engine is considered a mistake. Everone knows that valve-in-head is much better than the sidevalve design, albeit more expensive to manufacture.
The inlet port and valve is much more crucial than the exhaust for breathing and power. The only rationale I can think of is they must have been aiming for cooler exhaust valves as flathead engines, even liquid cooled car ones, are known to overheat especially in the exhaust area, and Indian Chiefs get 10 mph slower top speed as they get hot.
Indian Classic Motorcycles Other than the heat issue, for power if you can't have both vales in the head, the F head is the next best choice, and this was reverted to in 1938. At least the Sport model of the 1937 Four had two carburetors. With a Four, the more carbs the better. Most Indian Fours had one carb at the very back to cool the rear cylinder. (Same was used on the Ariel Square Four.) The downside is that the front cylinders get a tiny bit less fuel and air mixture.
In 1938 the company did a major redesign of the Four, generally considered a big improvement, but stupidly they did not take the opportunity to go to full OHV (it was still an F head) nor to go to multiple carbs, nor to increase the displacement. Displacement of the Four was always just over 77 CID or 1260 c.c. According to Harry Sucher (in his excellent book "the Iron Redskin") one can bore the Four out to 90 CID (1500 c.c.) and use Sport Scout pistons. One wonders why the factory didn't do this themselves.
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| Indian Classic Motorcycles |
Indian Classic Motorcycles In 1914 Indian had been the first with both electric lighting and an electric starter. All very advanced but they did not continue with the electric starters longer than six years nor with the OHV engines nor the 4 VPC engines. (They also tried the 1930's OHV engine in a car of their own design but hardly any were sold.) Had Indian kept using electric starters, OHVs and 4 VPC, they might well have been so far ahead of their competition as to be the dominant brand up to today. Its next major development came in 1916 when Hedstrom's former assistant Charles Gustafson developed the 1 litre "Powerplus".
Indian Classic Motorcycles Below we see two photos I took of Carmille Dansereau's unrestored 1917 Power Plus (61 CID or one liter) V-twin with sidecar. The date of manufacture indicates that this particular bike was built in Toronto Canada rather than Springfield Massachusetts as Indians were also produced for a few years in Toronto beginning in 1912 and through World War I. The middle of WW I (1916) was the first year for the Power Plus, and the first engine not designed by Oscar Hedstrom. Both Hedstrom and Hendee had left the company by 1916, being unable to agree with the Board of Directors.
Indian Classic Motorcycles In 1918 the company offered for sale to the public its own new factory racer featuring not only OHV but 4 VPC (valves per cylinder). This was many years ahead of the competition. Considering that 3 or 4 VPC only began to show up on a few street V twins bikes in the late 1980's and mid 1990's, and Harleys are still built with only 2 VPC, it can be said that this V twin was 70 years ahead of its time. Top speed was 120 mph, but the racers were very light and had no brakes, lights, fenders, suspension etc. The high price of this racer resulted in very few sales and it did not last long. Two years later, the Power Plus street model was offered in a 74 CID (1200 c.c.) version for sidecar owners. 1920 was also an important year as the Scout was "born" then. Originally it was only 600 cc. (37 CID) but was enlarged in 1928 to 45 CID (750 c.c.) and called the Scout 101.
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