Rochester Carburetor

[Erik412]

Good Afternoon,

I just received a Rochester Quadrajet carb and am having trouble finding info on it. The casting number is 17085004 3278 JMB. How can I find the specs about the carb and also locate a rebuild kit?

Thanks,
Erik

[MagicRat]

Any auto parts place would sell you a rebuild kit. But they need the vehile make, model and year to get you the right kit.

Just to make things hugely complicated, there were hunderds of variations on the basic Q-jet design, since these carbs were used on everything from the small Buick 3.8 (231 cid) v6 up to a 500 cid Cadillac engine.
While all these carbs have the same basic design, variations in the choke design, vaccuum sources, airflow, jetting, idle and main jet operation were made to suit a wide variety of functions.

When I have wanted to use a Q-jet of unknown origion, I go to a dealership to have them look up the numbers and identify the vehicle it came from. With that info, I can order the correct kit.

I have many service manuals with some carb info. My best guess is that your carb is from the 1982 model year, but I am not sure of the application.

(If there is a website to trace carb numbers, I would love to know about it. )

If that vehicle year and model info is not available, you might get lucky with a kit since one kit can service a wide variety of Q-jet carbs.
However, be careful if you want to put this on a car that was not intended for this particular carb. Sometimes differences in choke design, throttle linkage and vaccuum routing can take some work or fabricating to make it work.

Finally, over the years, I have accumulated several boxes of Q-jet carbs and parts. Sometimes I can mix and match parts to assemble a suitable carb for a particular purpose.
More often though, I throw another brand of carb (usually Holley) thats easier to work on, onto a car. Thats why I have boxes of Holley carbs as well.

[curtis73]

Rochesters that start with "70" are pre-1976. Since yours starts with "170" it means 76 and later. The "85" indicates the year. The next digit "0" is the carb ID and "0" usually indicates 49-state monojet. (more on that later) The next digit "0" indicates that it was designated for a Chevy

The last "4" indicates that its for an automatic tranny. The last four digits are the Julian date code, indicating that it was made on the 327th day of a year ending in "8" Probably 1988.

The reason for the messed up numbers is because many rochesters didn't follow this coding scheme. My dad had a 1978 truck that he bought new, and it had a Qjet that was numbered for a 1979 Buick. The numbering system was instated to make sense of the Qjets, but during the emissions era they were all so closely calibrated that often they were interchanged. I've even seen two of the same stampings on a carb with a front fuel inlet, and a side fuel inlet.

They also produced Qjets for replacement and often times they carried somewhat random numbers. Since yours was produced on the 327th day of 1988 but carries a 1985 date code makes me think that this was just that case.

At any rate, most likely the Qjet kit you get will be pretty universal. There are only about four different gasket formats possible, so if you buy a Qjet rebuild kit for a 1985 Qjet its probably the same kit across the board for all post 1976 Qjets.

My guess is you should get a kit for a 1985 Chevy Caprice, or maybe a Pickup with a 350, and you should be set.