Rochester Carburetor Numerical Index
Rochester carburetor numbers are stamped into the float bowl of the carburetor starting in 1968. Before that, they are found on a tag. Most 1967-down Rochester carbs have a triangular aluminum or brass tag retained by a screw attached to the top of the float bowl. 1965 to 1967 Quadrajets had a round 'bottle cap' tag on the front driver's side. Unfortunately, these tags and 'bottle caps' are often missing, requiring visual identification of 1967-down Rochester carbs.
Rochester Number Indexes & Guides
Rochester Carburetor Numbering System
By the mid-1960s Rochester carburetor numbers started to become mostly standardized. Here are a couple of Rochester numbers decoded as examples:
'70': until 1975, all factory production Rochester numbers start with '70'
'2': 1960's carbs generally have a '2' in this place ('3' in this spot means special emissions, eg. California)
'6': means theyear six of the decade (1966).
'203': means Chevy 4 bbl (Quadrajet); '3': means manual transmission. Odd number are usually manual transmissions.
'170': starting in 1975, most Rochester numbers start this way
'8': means 1980's
'212': means Chevy 4 bbl (Quadrajet); since this happens to be a truck carburetor, it could be manual or auto trans