Most people have no clue what a "3/4 grind" really means. Back in the dark ages (1930s and 40s) virtually nobody used duration and lift specifications to identify non-stock camshafts. They were called "1/4 race", 1/2 race, 3/4 race, or "full race" cams. The 1/4 and 1/2 designations went away, as they didn't offer a noticeable power gain over original equipment cams. "3/4" race cams stayed in production for people who wanted a lumpy idle and the ability to brag "I've got a 3/4 cam"! I always asked what the one fourth of the cylinders that didn't have a camshaft were there for? 264 degrees should be OK, as long as the lift isn't extremely radical. There will be a slight idle lope and low intake manifold vacuum, and a little loss of low end torque. Gear the rear end and pick a tire size to give highway cruise speed at around 2,000-2,500 RPM.
The only way to evaluate what you've got is with a dial indicator and a degree wheel- - - - -"3/4 cam" means exactly nothing to anyone with even a rudimentary understanding of engine building. I consider any cam with a duration of over 270 degrees to be unsuitable for street use, but "Opinions are like - - - -uh- - - -noses. Everybody's got one and they can be pretty smelly!" All of the major cam grinders publish detailed instructions about how to degree a cam. My first exposure to understanding cam degreeing came from a little soft cover booklet published by Ed Iskenderian in the early 1950s called "Top Tuners' Tips". If a copy still exists somewhere it's a good read- - - - -I highly recommend it!
Jerry
