Beware of the one-way venting valves. They Let air in as gas is consumed, and prevent vapors from going out. The problem that can arise is if you park the car with rather little gas in the tank for a long time and the ambient gets cold, So air goes in as that gas volume contracts. Then the ambient warms up, and the air/vapor in the tank wants to expand but can't, so pressure builds. It can be enough to overcome the float valves and then the float chamber overflows with gas and the gas goes down the throats, and in to the cylinders whose intake valves are open. Said gas can then go past the rings and if you're really lucky, fills the crankcase with gas on top of your oil. If you happen not to notice this, and then fire it up, the result will not be good. The gas/oil mixture will go out every available seam as the blow-by will apply some considerable pressure, plus the basic mechanicals of pistons going up and down, with lots of unapproved splashing. Great quantities of smoke may be evident. Ask me how I know.
I took my one-way valve out. I also store the car over winter with a full tank, so as to minimize the air-vapor volume. I route the vent hose up in a loop over the filler and just deal with a little gas smell now and then. Bug whup, its a Speedster ...