The smaller cap has a spring as well that holds it closed.
For 1950s–1960s GM Car & truck transparent bowl fuel filter 41-9360
Vintage 1950s Ford 27751 Heat Climate Control Chrome Auto Defrost Switch C-6439
1/2" Rear Aluminum Coil Spring Spacer Lift Kit Set Pair 1960s GM RWD Made in USA
1.5" Rear Aluminum Coil Spring Spacer Lift Kit Set Pair 1960s GM RWD Made in USA
1950s–60s GM Car truck transparent bowl fuel filter For 1 or 2-barrel carburetor