If I have a summit plastic fuel cell, do I have to use the charcoal cannister or a vent tube?

 

You need to use a vent tube for sure. If you suck fuel out of the cell then air has to get in somehow to replace the fuel you just sucked out. The charcoal canister is purely for emissions and since this is a racecar you can chuck it.

Make sure you have a check valve on the vent tube, it should only allow air in, not fuel out...

 

So I can take the charcoal cannister system off, leaving only the main carb feed and the return line right?

 

the cannister is not needed, but a vent with roll over protection is needed. the supply and return for the carb is correct but a third will need to let air into the cell. so when the fuel is removed the air will enter and cell will not collapse. This is best accomplished with a rollover check valve available from most cell manufacturers. Last item is that I don't recommned rotary molded fuel cells(hard plastic cell) for any application. they tend to break and crack with hard impacts. I know they are less expensive but use the OEM tank or a proper ballitic bladder type cell. last I checked the rotary molded cells were not allowed in NASA competition. check the rules with the sanctioning body you plan to race with. be careful and good luck

 

So I need a fuel cell tip over valve, do I need to vent that with a hose at all?

Theoretically, if I didn't roll the car, would the tip over valve and an open vent in the tank be the same?

 

I just checked and the fuel cell I have has a one way flapper valve in the cap to let air in when gas is sucked out. So all I should need to do is cap the top with the 6AN and run my main feed and return in the sump.
Is it ok to run the return back to the sump or does it go to the topof the cell?

 

usually the top of the cell but either will work.