I have built a ’69½ Road Runner 440-6 clone. I’ve been fighting a fuel leak problem on my fuel tank for the last 2 years now and I just can’t understand what actually causes it. Here’s the problem: Every time I fill up the tank (hardly up to ¾ full) the short vent tube clone. I’ve been fighting a fuel leak problem on my fuel tank for the last 2 years now and I just can’t understand what actually causes it. Here’s the problem: Every time I fill up the tank (hardly up to ¾ full) the short vent tube (the one that just has a U-turn up and back down again) on the tank overflows like crazy. After a certain amount of time, of course, it will stop when the fuel level goes down to a certain point. It stops when I take off the fuel cap. By the way, is the original cap ventilated? Last year I took the long vent tube (the one that goes up in to the trunk compartment) out because after tying to blow com- pressed air through it I realized that it was clogged. I thought: OK, this is the problem. I fixed it and put it back only to realize, after the next fill-up, that the problem is still the same. I can’t understand why the fuel gets up until overflow level. The tank is new. Can the vent lines (short and long) be attached to either of the vent line connections on the tank or do they need to go on in a specific way? At what level do the vent line connections end inside of the tank? Is it possible that the connection tube on the tank from the long vent tube is clogged inside the tank?
It appears that the tank you used was made for California emissions for the 1970s (with charcoal canister). Assuming you don’t have that, the second (short) vent hose and tube should be removed, and the nipple capped off. There should only be ONE vent— the long one. The cap is not vented. If you have erroneously used 1970-’71 carbs, the vent nipples on the float bowls should be left uncapped (open).