[DanEC]

Yeah - once followed by a loud boom. FE's are pretty tough. I'm sure I've bored plenty of people with my story of my High School buddy whose parents bought him a new, off the showroom floor, 1969 390 auto Mach 1 Mustang. He was running it through the gears the same day he picked it up, going as high as it would go - and nobody thought a 390/315 HP was supposed to go very high. He was a believer that if you wanted a fast car, break it in hard and fast. Apparently not satisfied with the factory tach he bought a nice Stewart Warner tach and mounted in on the column. The only thing he did to the car was pull off the muffler, leave the resonators and run straight pipes out the rear. A few weeks later we took it out on a new stretch of recently opened Interstate to see what it would do with 3 people in the car. I was in the back seat and watched him hit 6000 rpm in all three gears with the speedo reading around 130 mph in 3rd. If I hadn't watched it with my own eyes I would not believe it and would not blame anyone else for doubting it - but that's what I saw. Of course a year later he was hitting valve float at a little over 5000 rpm.

I kept track of him and this Mach 1 for several years and even after countless high rpm runs and shifts he never managed to blow the thing up. The valve springs were probably his saving grace.