Landracing Forum
Tech Information => Technical Discussion => Topic started by: QikNip on October 15, 2016, 11:50:17 AM
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Rule 3.1 states,"All fuel tanks shall be vented to eliminate spillage in the event of a rollover." Does this mean a (Classic Production) car with an unmodified OEM fuel tank system (which has a factory vent that's plumbed into the filler neck) must have a non OEM rollover valve plumbed into that vent line? Related to the vent line question, if the tank's filler pipe does not have the type of rollover ball valve found in modern fuel fill necks, does the (threaded) OEM fuel filler cap allow that tank to meet this rule?
Rick
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If you flipped your car over onto its lid, would fuel come out of any where in its current configuration?
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Rule 3.1 states,"All fuel tanks shall be vented to eliminate spillage in the event of a rollover." Does this mean a (Classic Production) car with an unmodified OEM fuel tank system (which has a factory vent that's plumbed into the filler neck) must have a non OEM rollover valve plumbed into that vent line?
That's how I handled it on the Midget in GT, which is also a production class. At the end of the day, what Nate just described is the goal.
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Thanks. To clarify, you installed a rollover valve in the vent line on your midget (that was itself plumbed into the filler neck? As for leakage per Nate's comment, I guess I'll remove the filler neck, invert it, put the cap on and fill it with liquid to see if the cap actually seals it completly. Assuming it does, then no rollover valve of any kind would be required.
If it doesn't then a vent valve isn't a total fix. In that case what do others with OEM fuel tanks do to positively prevent leakage? As an aside my Spec Miata had a factory ball valve in the neck to seal the tank in the event of a rollover. BTW, I know that works since that car once spent ten minutes on its lid with nary a drop leaking!
Rick
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Update... I removed the filler neck, put on the cap, inverted the assembly and filled it with gasoline. It did not allow any fluid to escape. I even blocked the vent line connection and applied a bit of air pressure to make certain and confirmed a complete seal. Given this test, I'm confident that with the car upside down the tank system will not allow gasoline to escape. But I'm now questiuoning how the tank system is venting to allow air to replace the fuel as it's consumed. Therfore I'll install a vent line rollover valve and block off the fill tube's vent connection to assure that the tank is venting ... and to make tech totally comfortable. Case closed. :-D
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I vent in one corner--run vent line diag. across to the tank and secure the line below the bottom pointing down fuel can not run out no dips or loops to cause a P trap effect---you want it to vent--do not skimp on the diameter