No history of American motorcycles in the first half of the 20th century is complete without mention of the Crocker. Crocker made very successful single cylinder Speedway race bikes, and V-twin street bikes. Like the English Vincent this big V-twin was very fast and technologically advanced for its day (1936), and the bikes were hand built, so they were expensive and rare even in their day. (The war put an end to American and English civilian motorcycle production in 1942, and while Indian, Harley and Vincent resumed after WW II, Crocker did not.)
The Vincent V-twin came into production about the same year as the Crocker and Harley Knucklehead (1936). The Crocker only lasted until 1942 and the Vincent until 1955. The Harley evolved into the Panhead in 1948, the Shovelhead in 1966, the Evolution in 1984, and more recently the Twin Cam.
Probably no two Crockers were alike even when brand new. Buyers could order engine sizes from 61 (1 liter) to 100 CID (1.5 liters or 1500 c.c.). While the Vincent was fast but fragile, the Crocker was fast and rugged. Parts were made overly strong for the power output, understressing them and making them reliable. While the Crocker was like a big Detroit V-8 car of the fifties, the Vincent was more like a finicky British sports car. (Not that people then and now have not racked up tens of thousands of touring miles on Vincent Rapides - I am thinking more of the Black Shadows and Lightnings. The Vincent engine design was much more complex than the Crocker or for that matter any V twin made in the following half century. The Vincent rear suspension was not copied until the Harley Softail and the oil-in-frame design was copied in a street bike until Triumph and BSA used it in their 650 twins starting in 1971.)
While the Vincent was unique in appearance, the Crocker looked familiar: like a stripped down Indian Chief with Harley Knucklehead engine. Actually Albert Crocker used to work for Indian so resemblances between Crocker and Indian parts (tanks, Scout-like forks, aluminum primary cover and generator drive location) are not just coincidence. While some parts were obtained by Al Crocker from Indian and Harley dealers, it is not true that the bike was a combination of Indian and Hog parts. The frame (which included a cast-in steel gearbox), forks, engine etc. were pure Crocker. Many parts which on other bikes were pressed steel or cast steel were made of aluminum; even the fuel tanks. The gears were oversized for strength, but only three speeds were available. (That was standard in 1936.) The engine was of valve-in-head design (OHV) and had an almost square bore and stroke ratio. That ratio was truly ahead of its time as until about 18 years ago V twins on both sides of the Atlantic except for the Vincent and Crocker and Moto-Guzzi had narrow bores and long strokes.
The Crocker came out in the same year as Harley's OHV Knucklehead, but beating Harley to the market by about 5 months. Early Crocker V-twins were hemi-head with exposed valve springs, but some of the heads cracked. The later design was called "parallel" and had fully enclosed top end. I am not sure of whether the valve angle was more vertical like the latest designs or not. From what I understand (and probably nobody had dynometers back then) power output of the two designs was equal.
Apparently Harley and perhaps also Indian felt so threatened by the more advanced and fast Crocker that they pressured Budd and Kelsey-Hayes, the wheel rim makers, not to deal with Crocker, so Crockers were sold without wheels and buyers had to buy them under the table from sympathetic Indian and Harley dealers. According to one story, during the early 1940's Mr. Al Crocker, seeing the writing on the wall, approached Indian about buying the rights to his engine for use in Chiefs. As is typical of the Indian management of the 1940's, and Indian's own failing finances, they turned their noses up at a golden opportunity and looked a gift horse in the mouth, just as they did in 1949 when they had the chance to power new Chiefs with Vincent engines. Thus the postwar Indian V twin never became an OHV.
Al Crocker made over 60 V-twins plus successful Speedway singles and had another 85 V-twins almost finished in 1942 when the War Dept. forced him to melt them down for badly needed metal. He then made so much money making military parts he did not resume Crocker production after the war. He died in 1961.
A restored Crocker today is worth far more than an Indian or Harley V-twin of the same era. I mean eight to ten times more. At auctions since late 2006, well preserved or restored Crocker V-twins have been sold for a quater million dollars! I guess most of us won't ever own one. As a side note I was in the shop of a noted Indian Moto-Cycle restorer and noticed a basket case Crocker laying on the floor. He said they were over rated...I guess you can say that if it's not yours !