Very common/chronic C1 issue. For safety's sake, first check the fuel pump and the plumbing from there to the carb for any leaks; if you have any and the rubber seal on the back of the hood is missing, engine compartment fumes will exit the rear of the hood and go straight into your open cowl vent.
The more common causes are related to the fuel tank. Remove the tank cover panel and look for any leaks around the tank or at the sending unit. Check the fuel fill hose for dry-rot, cracks, etc. There's a vent hose from the passenger side of the top of the tank that runs across the tank, through a grommet, into the gas door cavity - check it for cracks/leaks.
There's a nipple and drain hose at the bottom of the fuel filler door cavity; there should be a drain hose from there through a grommet directly below it in a 1" hole in the underbody so any spillage in the cavity drains out onto the road. This hose and grommet are almost ALWAYS missing, so the spillage just dribbles down into the underbody cavity below the fuel filler hose and pools there, causing a major fuel odor in the cockpit.
Finally, make sure you have a non-vented gas cap that seals properly to the filler pipe; when you turn right with more than a half-tank of fuel, gas runs up the filler hose and will leak into the filler cavity if the cap doesn't seal well.
