That bolt, no kidding!
My brother bought the "Car of the Decade" in 1972, the Mach I Mustang with the Cleveland 4-bbl engine. He later added the ram-air package because Ford wasn't allowed to sell the ram-air with the 4-bbl at the time, only with the 2bbl carbs. After sorting out the difference in carburetion the ram-air caused (lean when open and above 70 MPH) we dominated his local [rural] Saturday Night stoplight challenges. Some of the earlier champions of that title got a little jealous/zealous about it and one night slipped a couple of nuts inside the carb's secondary plates (the hoods didn't lock with an inside cable pull like most do today) and waited until the next Saturday, then called him out. He drove all that week without opening the secondaries: that Saturday night he got 1 block during a challenge before the engine started banging loudly and he shut it down. While the 2nd nut was never found, the first nut looked much like the bolt in your picture above! He replaced the piston and rod bearing and drove on to almost 180k miles before rebuilding the entire car about 5 years ago, looks brand new again.
