The gunk forms a thick layer at the bottom of the tank. It is unlikely any will get sucked up. Also, very little fuel actually gets pumped, so there is more than enough time for any dirt to drop back to the tank long before it gets to the pump or carbs. With FI there is a huge volume of fuel circulated constantly, requiring a high quality filter, but with carbs the amount of fuel pumped = the amount of fuel used. So unless your car is extremely heavy on fuel... This is exactly why you do not need a fuel filter at all. Mine is there because it has always been since the first or second service. I got the car only recently off my father, and will remove the filter soon when I replace the cracked fuel line. No need for it to go back on. When I rebuilt my carbs recently, there was gunk in the reservoir although I did have a filter! I think it this case it also had to do with when fuel stands for a long time. My father had the car at home in storage, and for 5 to 10 years just started the engine once a month. Then there is also the dissolving and cracking (very slow, but after 30 years...) of the fuel lines. Where do you put the filter for that? That's part of the reason why there are small permanent filters inside the carburettors.