Bought a Holley HP 750 last year (right about this time).
Car suddenly would not run down low or idle on Sunday. Took both fuel bowls off and noticed that the plating inside the bowls and the metering blocks was cracking and separating from the aluminum. Small pieces had broken off and clogged some of the orfices in the primary metering block.
NICE! $500 carb now junk.
Called Holley this morning. Evidently they had some problems with their silver plating about a year ago. They are replacing the whole carb for me.
If you bought a Holley with the silver plating within the last year, ya might want to take the bowls off and take a look.