Someone please give me some good advice

RAbarrett · Mar 23, 2006

The nproblem here is that the "precision" required to properly position the rods in the jets is lost when you bend your own. My concern is whether the hangers are still "unmolested." Bending your own is asking for trouble, however, I agree about the "excitement" over a hanger. Ray

TORQUED455 · Mar 23, 2006

Having witnessed how the carbs were set up from the factory, it is all but impossible to duplicate the precise settings the factory had. I hear of people drilling jets, sanding rods, etc. Unless you have a wet-flow bench and some highly-specialized tooling, who knows what your results will be. That's why it takes alot of tinkering to get them to perform where you think its best, which may be in direct contradiction of what's suppose to be coming from the tailpipe!

carbking · Mar 24, 2006

TORQUED455 said:

There is no such thing as a carb rebuilt by GM, as GM never rebuilt carbs. If you are referring to a technician at a GM dealer rebuilding a carburetor, then that's something different altogether.

Rochester Products Div of GM used to make "service" runs of new carburetors. If I recall correctly (I was an engineering student at RPD back in the early to mid 80's), there were 3 or 4 Quadrajet assembly lines. One of them, at times, was dedicated to making new, service replacement carburetors. There was even a marine line too.

You will sometimes run across a "funny" Q-Jet number, and that's the reason why. They were low production runs, and if you recall, it took quite some time to get a new carburetor from a Delco distributor after placing an order. Once enough demand was there, a run was made. I believe that a service replacement carburetor would fit more than one application.

Carburetor remanufacturing companies have been butchering carbs for years. Pot luck with them!

I too have noticed the quality of QJ jets, rods, hangers, etc have gone down since RPD sold off the carburetor business. The secondary metering rod plating (a nickel-based plating if memory serves) caused a lot of rods to be rejected because the plating would crack during the hanger-end bending process. I was able prove that plating could be done after the bending process and still be able to maintain the very tight tolerance requirements that the calibration process required. I was never able to implement the process because the writing was on the wall for production carbs to RIP.

Another little tid-bit about the secondary metering rods hangers that not too many people know about - the reason for the different hangers (denoted by letters) was for different placements of the rod holes. This was not done to richen or lean the secondaries, as every seems to think!! It was done to get the secondary tip in a precise position in the secondary jet. Due to manufacturing tolerances, each carb was a little different. In one of the last stations on the assembly line, a worker would insert a gauge into the secondary jets and take a measurement from the jets to a point somewhere on the airhorn (I forget where), and depending what that measurement was dictated what hanger that particuliar carb got. 15 Q-Jets of the same number can have 15 different hangers. It is reasons like this that a carb can never be put back to the way the factory designed it, but we can still make them work.
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Bob - I never had the priviledge of working for GM, so I envy you in that respect. However, I would like to ask questions about a couple of statements in this quote.

First - GM never rebuilt carburetors. As I said, I wasn't there, so don't know; but GM did sell rebuilt carburetors (we used to buy them, and still have the cataloguing). GM had lines of both rebuilt and new service carburetors; and the rebuilt ones were much better than the average commercial rebuilder, in fact, we found the rebuilts to be as good as the new, and less expensive. Might you know to whom GM sublet these rebuilts?

Second - concerning the hangers. I personally have no knowledge (and no desire to learn) the newer (I define newer as 1975 - up) stuff; but have several assembly sheets from the 1960's and 1970's which specified a specific hanger. Several engineers and quality control people from Rochester have told me the assembly line could vary plus or minus one hanger size (as you mentioned) but if more than that was required, the unit was rejected. Did you really mean 15 different carbs of the same number could have 15 different hangers, or was that a figure of speech? Do you have any of the early assembly sheets showing which hangers were used? I would love to add to my database.

Thanks in advance.

Jon.

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Someone please give me some good advice

RAbarrett Well-Known Member

TORQUED455 Well-Known Member

carbking carburetion specialist

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