How did this happen?

[trans am greg]

 So last week i had to replace intake gaskets do to a blowout of the crossover block offs.
 I held the carb up to look at the bottom and saw my pri. throttle plate screws backed out.
 This carb was rebuilt by Cliff about 6 years ago. I screwed them back in, but how can it be prevented
 from doing it again?

[Ethan1]

So last week i had to replace intake gaskets do to a blowout of the crossover block offs.
 I held the carb up to look at the bottom and saw my pri. throttle plate screws backed out.
 This carb was rebuilt by Cliff about 6 years ago. I screwed them back in, but how can it be prevented
 from doing it again?

 It is as simple as staking the ends of the screws. A steel punch and hammer will "mushroom" it enough so they will not back out.