Originally posted by ovfi
Mike, thanks for your precise answer,I think you have a lot of knowledge about these cars....
Now, as you have informed that this design is owned by A.J.Watson, I suppose that Rodger Ward's 1959 dirty car was a Watson too... but I think Watson made similar cars before 1959. Do you know the year when Watson begin to make dirty cars with this design?
  Sorry for the slow response, ovfi. I'm afraid that I do not have a great knowledge of these cars. I just have access to good sources, like Dick Wallen's
Fabulous Fifties book.
  AJ Watson was building upright championship cars in the early 1950s. He built a very good car for John Zink c.1955. It was driven to victory by Bob Sweikert and, later, Jud Larson. I suppose there is a generic resemblance between those early cars and the Watson dirt car in Vince's picture and the Blum copy in your picture - in the sense that all dirt cars look somewhat alike. But if you compare photos of the Leader Card Watson or the Blum to other cars of the same era, you will see some obvious differences - particularly with regard to the suspension design. When Watson hooked up with Jim Wilke's Leader Card team after the 1958 season, he was given the money to build two roadsters and a dirt car. That dirt car is the car in Vince's photo. It was not the same as Watson's pre-1959 dirt cars. Watson may not have invented that front suspension design (the prominent cross tube, etc.), but his 1959 design made it successful. You will need someone else to tell you how it worked and why it worked so well. Rodger Ward and Wilke's other driver, Don Branson, won a lot of races with it. The car that Watson built for Ward in 1959 was still competitive in 1973. George Snider used that very chassis to will the USAC Silver Crown championship. It is also, BTW, the chassis that Jimmy Bryan was killed in at Langhorne in 1960. Quite the history for one car, isn't it? Little wonder that Weinberger wanted one. The Weinberger is certainly a copy of the Leader Card machine. How it came to be, I do not know. It must have been assembled by Blum - hence its designation as a Blum, rather than a Watson. Watson may have sold the plans to Blum, or he may have sold him a kit. The bodywork is identical, which suggests that it was purchased from Watson, but I'm really just guessing. Rather a long winded way of answering your original question, eh? Bottom line: the car in your photo is a Blum copy of a Watson dirt car, of a type that first appeared in 1959.