Chevrolet Bel Air Ignition Bulb Size

Additional Notes

• The bulb type 53 is the most frequently specified ignition bulb across the Chevrolet Bel Air lineup, covering model years 1955-1963. It follows the ANSI standard for the US and Canada, operates at 12V with a 2W output, and uses a single-filament design with a BA9s base.
• The BA9s base, shared by both the 53 and 1445 bulb types, is a miniature bayonet cap with a 9mm cap body. It is a common base format in low-wattage automotive instrument and indicator applications.
• The 1445 bulb replaced the 53 for the 1964-1967 model years. Both types share identical electrical ratings of 12V and 2W and use the same BA9s base, which places them in the same general category of miniature single-filament bulbs.
• Despite the shared BA9s base and identical voltage and wattage ratings between the 53 and 1445, they carry distinct ANSI designations, and fitment should be confirmed against the specific model year rather than assumed interchangeable based on electrical ratings alone.
• The 1968 Chevrolet Bel Air uses the 1895 bulb, which represents a departure from the BA9s-based types used in prior years. The 1895 is a T5 miniature wedge bulb operating at 12V and 0.9W, a notably lower wattage than the 2W rating of the 53, 1445, and 51 types.
• The T5 designation of the 1895 bulb refers to a tubular glass envelope with a width of 5/8 of an inch. The wedge base design eliminates a separate metal base, with the glass envelope itself acting as the retention mechanism within the socket.
• The 51 bulb was specified for the 1953-1954 model years and uses a BA15s bayonet base, which is a single-contact bayonet cap with a 15mm cap body. This base format is physically distinct from the BA9s used in later Bel Air ignition bulb applications.
• The BA15s base of the 51 bulb is not compatible with BA9s sockets, meaning the 51 cannot be substituted into sockets designed for the 53 or 1445 types despite sharing the same 12V and 2W electrical ratings.