Mankind has been trying to stop the SU carburetor from overflowing since the dawn of time, with limited results. We love SU carbs, (and we have 100 of them in our building on any given day), but their needles and seats occasionally get clogged and then fuel flows out the overflow all over the ground. Perhaps back in the day when fuel was less than a buck a gallon people didn’t really mind, but nowadays, since nothing leaks anymore, it causes a lot of commotion to have a somewhat flammable puddle forming under the front of your hot car. So how do you make this ancient technology work so you too can drive your 948 powered Bugeye 4001 miles, like the Larricks just did in their Bugeye “Ducky?”
The first step is to make sure you have a great fuel source. Most Spridget fuel tanks are full of old rust particles. We’ve even had a few cars come with wooden sticks previously dropped down the filler neck. If you look down in your tank through the neck and see a bunch of Sea Monkeys waving back at you, a new tank is in order. And if you have a pile of sediment in your float bowls, that will get stirred up and clog things too. So make sure to run a fuel filter and clean out the float bowls too.
Once you have a first pressed virgin gasoline flowing through the system, the next area of concern is the needle and seat in the float bowl. The grose jet was supposed to be the best solution here, but we have not had good field results from this product and have instead found that the Viton-tipped needle works best. This is the needle and seat we used on Ducky for the cross country trip, without a single overflow.
Check out the video below, and if you are having overflow issues, hopefully this post will help you get back on the road dribble-free.