Biff, I don't know exactly what the stock specs for a 250 cam are, and they're very difficult to find. However, whatever the specs for the factory cam are, they aren't impressive in terms of performance. Chevrolet used such restrictive intake and exhaust manifolds that a cam with very much lift or duration wouldn't make much, if any, difference in the engine's performance. So the stock cam specs for most of the GM inline sixes (the Pontiac SOHC six and the original Corvette six being the 2 exceptions) were pretty anemic. I used an RV cam (256 degrees duration, .480" lift) in the first six cylinder Chevy motor I built, and when I put the stock cam and the aftermarket cam side by side, the lobes on the stock cam looked pathetically small. However, when I got the new cam installed and the engine in the car and running with the factory manifolds, I couldn't tell any difference in performance between my hopped up motor and a stock one. Until I put a Clifford intake and headers on that engine, that is. Once the breathing was opened up some, the cam came alive, and really made a difference in the performance. Letting your engine breathe will make the biggest difference in performance. In general, most of what are termed "RV" cams are great street cams........lots of low end and midrange performance with headers and a good intake. Hope this helps some.
