Topic: Purchasing a rochester Q jet
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
Lifetime Member
(Just kidding
)
It's a small difference in the bracket on the side of the carb, but not being an expert myself, I can't offer more than that basic info. The two used Q-Jets I've bought have been for auto trans, so I can't say what the manual version looks like from personal experience.
Eric,
The Q-jet oem numbers go like this:
70YYEDT or 170YYEDT
70: Rochester carbs started with either 70 (before 1976) or 170 (after 1976).
YY: The year code. The years are a little convoluted, but probably the easiest part to remember.
| 1965 | 25 |
| 1966 | 26 (or 36 on A.I.R. engines) |
| 1967 | 27 (or 37 on A.I.R. engines) |
| 1968 | 28 (or 38 on A.I.R. engines) |
| 1969 | 29 (or 39 on A.I.R. engines) |
| 1970 | 40 |
| 1971 | 41 |
| 1972 | 42 |
| 1973 | 43 |
| 1974 | 44 |
| 1975 | 45 |
| 1976 | 56 (the year they started the 170 prefix) |
| 1977 | 57 |
| 1978 | 58 |
| 1979 | 59 |
| 1980 | 80 |
| 1981 | 81 |
| 1982 | 82 |
| 1983 | 83 |
| 1984 | 84 |
| 1985 | 85 |
| 1986 | 86 |
| 1987 | 87 |
| 1988 | 88 |
The code for 1965 would be either 25 or 35, 66 would be 26 or 36, 67 would be either 27 or 37, etc. 1970 is 40, 72 is 42, 75 is 45. You get the idea. The 80s are easier because they're usually straightforward. 81 is 1981, 84 is 1984.
E: The emissions code. 2 is for 49-state emissions, 5 is for California & high altitude.
D: Division. 0, 1 and 2 are Chevy, 3 is Cadillac, 4 is Buick, 5 is Oldsmobile, 6 and 7 are Pontiac. Rochester doesn't always follow this rule.
T: Transmission. Even numbers are automatic trans, odd numbers are manual trans. Rochester also doesn't always follow this rule.
This guide is just that: a guide. It is not set in stone, because it is a documented fact that Rochester didn't follow these rules 100%