source for stock Q-jet calibrations??

k10caddy

k10caddy

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I've looked all around online and haven't yet found a listing for what quadrajets came with what jets/rods/spings. I haven't yet picked up Doug Roe's book. suffer from PBS. I do have a '76 GM caddy service manual that helped with basic settings and diagrams. but it doesn't specify whyat jets/rods/springs were used.
I'd like to find a list of exactly what all these various quadrajets came with (or were supposed to) so that I know. can someone offer a source? or any other help? does Doug Roe's book have this info?   ???

also I'd like to add that so far I've got to say that the rebuilt quadrajet has performed better than the edelbrock 750 that I used last year.
I've noticed some people give me the hairy-eyball when I say I actually like a q-jet better than an edelbrock. lol
 
Inernal componets can vary geographically, especially from CA and in states at high elevations like CO, this one is from an NC yard.

17056230 From ’76 500 RWD, Jets 70; primary rods 40 L; hanger P; secondary rods DH

Q-Jet is the best gas mileage/performance combination carb extant.
 
Cadillac factory shop manuals will have this information. They're the only place I know of to find it. But even then they don't mean much. The specs vary from year to year, even across years where the engine was identical right down to the cam. And the carburetors I've seen that I know had never been modified didn't match what was specified in the factory shop manuals anyway. If you've made any modifications to the engine, even as simple as a dual exhaust, the factory specs wouldn't be any good even if they were right to begin with, which they weren't. I wouldn't spend too much time wondering what was "supposed" to be in your carburetor. You'll do best to tune the carb to your own application.
 
maybe the earlier ones had it but the GM cadillac shop manual I have now doesn't specify what's supposed to be there., if it did I wouldn't be asking. I've spent 3-days reading the thing. I really want to know for certain what's supposed to be there to help determine what I need and if someone else has already done anything to this one.
the manual gives the other specs on damn near everything else 'cept the rods/hanger/jets. :banghead:  I've got an 'R' hanger and, I think, 'CE' secondary rods. don't know what it's got on the primary side, though. never looked and don't want to tear it apart now that it's on the truck and working. 
1%, thanks, that's a partial start. I've got the same carb #, which btw, is for federal emmisions cars....iirc, cali and commercial chassis w/145 amp gen. had a 17056530. altitude option was 17056232 
 
Did you read my post far enough to see the part where I said, "the carburetors I've seen that I know had never been modified didn't match what was specified in the factory shop manuals anyway", or was my post too lengthy for you to digest all at once and you skipped out? Even if you found factory specs for your carburetor, that still wouldn't tell you whether anything had been done to yours already. Factory specs given for carburetors are unreliable.
 
K10,
My 2 cents, fwiw;

Even if the data you find is correct, I doubt that stock metering parts will be ideal. Assuming that the stock parts would be optimum for a stock caddy [which I doubt they would be], change anything and the metering parts needs will probably change too. Cam timing, intake and exhaust tract changes, etc, etc will effect the way the carb reacts.

Bottom line is, give the engine the amount of fuel it wants at all rpm and throttle openings. Easier said that done, I admit.  A wide band 02 meter is most helpful, but you can tune w/o one.

What are you trying to do, exactly, and why does it matter to you what metering parts the carb came with?
Dave
 
pageboy, yes I did read your entire post.  and to clarify further, can you explain further why you say that the factory specs unreliable?
sorry, I just wanted to know. I prefer to know what I'm talking about instead of sounding like an idiot.
 
FWIW -- The factory specs are a good place to start with near-stock motors, this based on using an O2 senosr & EGT for years.
 
I'll quote myself again. "...carburetors I've seen that I know had never been modified didn't match what was specified in the factory shop manuals".

I have two '68 Cadillacs myself, and I know enough history on them both to know that the owners never played with the carburetor tuning. (On one the previous owner is my dad.) One had a .070/.044 jet/rod combination, the other had .070/.042. I have several other Q-jets that either I took from '68 Cadillacs myself, or can be identified as a '68 model from the numbers. By far, most of them had .070/.044, but all told in all the '68 Q-jets I have seen, I have seen .070 and .072 jets, and .039, .042, and .044 rods. A '68 factory shop manual specifies an Eldorado to have a .068/.039 combination, and all other models to have a .069/.043 combination. I have never come across a Q-jet of any year that had .068 or .069 jets, or .043 rods. Only one of them had .039 rods, but it came with .070 jets, not .068. Nothing I have found in a carburetor was even close to what the factory shop manual specified. And I have little reason to think that subsequent years would suddenly show a different pattern.

Why does the Eldorado specify different calibrations than all other models, when the engine was otherwise identical right down to the cam? And then in '69 and '70 the carb calibrations are different again, even though the exact same cam was still used, at least according to the cam specs given in these manuals. Why so many different calibration specifications on an otherwise identical engine? The factory carb specs don't make much sense all by themselves. And when it is realized that what is found in carburetors virtually never matched what the shop manual specified, it makes the carb calibration specifications given in the shop manuals absolutely worthless. At best, they're little more than a rough starting point. Whether you can find the factory specs for carb calibrations or not, you'll do best to start with whatever is in the carb now and tune it from there to your application.

Through a friend of mine, I have access to every year of Cadillac factory shop manual between '56 and '75, and I have copies of the pages with the Q-jet calibration information from those manuals for all the years it was used. However, I can't seem to turn them up at the moment. If the '76 shop manual doesn't have the information, it must be the first year they quit printing it. As far as I know, the factory shop manuals are the only place to find carburetor calibration information for a specific application. I've never seen a book or article on general tuning of the Q-jet that has this kind of information.
 
pageboy, thank you for you explanation and some extra info.
 
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