TheNeedForZ Posted January 2, 2005 Share Posted January 2, 2005 The Q-jet on my car is like this : number : 17059206, and then 0869 CBF front vacuum break assembly is missing a duct that goes into choke thermostat housing is cut and not hooked up (I think hot air or whatever is supposed to enter the thermostat housing thru the duct and heat up the coils. The duct should go somewhere but I dunno where and neither 2 of my Q-jet books show how to set it up) The number suggests a 1979 Q-Jet in federal standard, made for an automatic transmission Chevy. Production date is 86th day of 1979. It could be the original carb for this engine since my engine/trans is a Chevy with TH350 3 speed automatic. I would like to know how to complete the setup, and where to get parts. Also if I replace the choke setup with divorced type, i.e. the coil mounted on the intake manifold, would that be better? Thanks in advance Quote Link to comment Share on other sites More sharing options...
Sumo Posted January 2, 2005 Share Posted January 2, 2005 Have you ever thought of just buying a replacement carb? Kinda like these. http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=695&prmenbr=361 or check out their selection. http://www.jegs.com/cgi-bin/ncommerce3/CategoryDisplay?cgmenbr=361&cgrfnbr=641 Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 2, 2005 Share Posted January 2, 2005 The vacuum pulloffs are available at your parts store like napa, kind of pricey, 35 to 45 apiece, maybe more now, it's been awhile since I bought any. The choke linkage or duct is a gm kind of thing. Better yet is to find a later qjet that has an electric choke they work much better than the hot air ones. Also with the hot air you have to have the early manifold that accepts the hot air piping that fits in the heat cross over portion of the manifold. With the electric choke, wire it to the alternator output. This way if the engine dies for some reason the choke doesn't continue to release like it would if it were connected to a switched 12V source. Quote Link to comment Share on other sites More sharing options...
Guest Magnum Rockwilder Posted January 2, 2005 Share Posted January 2, 2005 How to Fix a Quadrajet: 1. Remove Quadrajet. 2. Curse at Quadrajet. 3. Throw Quadrajet in trash. 4. Bolt on Edelbrock or Holley carb. 5. Smile and nod... cheesy thumbs-up is optional. Quote Link to comment Share on other sites More sharing options...
RPMS Posted January 4, 2005 Share Posted January 4, 2005 I got replacement vacuum pulloffs from my local carb rebuilder for about $25 each. They've been very good to work with, selling me all the small parts I need at pretty cheap prices. And Magnum? I haven't personally tried every carburetor out there, but it's my understanding that a properly set-up Q-jet will be smoother and more consistant than most other carbs out there. I hear over and over that Holleys are easier to adjust and tune, but don't have the ultimate driveability of a Quadrajet. It's kinda like learning to adjust the dual carbs on the 240 - it's work, but ultimately worth it. Quote Link to comment Share on other sites More sharing options...
Guest Magnum Rockwilder Posted January 4, 2005 Share Posted January 4, 2005 You're right. A well adjusted Quadrajet is a great street carb, but the phrase "well adjusted Quadrajet" is an oxymoron. I've never had any luck with them, and have never met anyone who has. I have a mechanic buddy who can set them up perfectly in a half hour, but he runs Holleys on all his cars. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 5, 2005 Share Posted January 5, 2005 Well, if you lived in the same state, i'd come over and show you all I know about qjets and when you get it right, they work awesome. People just need to know how they work, they are infinately adjustable from jetting to air valve setting without buying secondary springs. I have a pile of qjets and parts, so if your looking for primary or secondary hangars, rods, or other pieces, let me know. When setting the primary metering rod depth, lower the adjustment about 3/16" of an inch, leans out the primarys at cruise part throttle only, sure to see a mpg increase over the stock setting, there are several ways to do this depending on year of carb. 3/4 turn from just touching on the air valve for sbc's. Change hangars, rods and cams for tuning secondary fuel rate. Read the plugs. GM has a list of rods and their relevance to rich or lean for both primary and secondary rods. As well, they have cam sizes, rates, etc., Read the directions that come with the kit, if you have questions, ask. Sometimes, somebody already screwed up the carb your working on and it is hard to figure out what is wrong and how to fix it. David Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted January 8, 2005 Author Share Posted January 8, 2005 Thanks for your inputs. dr_hunt, PM sent Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 16, 2005 Share Posted January 16, 2005 Ok, Z, finally got off my lazy butt (been one hell of a bad week) and looked through my qjet piles. All I have is later model electric choke versions that are complete. I do have heat choke parts, but not in a complete form to send you one. What else can I help you with? Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted January 18, 2005 Share Posted January 18, 2005 Spread bore Q-jet 4bbl. Had one on my cadillac, it took me months to figure it out, but when I did, it was at least 25% better from adjustment alone. It did have one curious feature, when I reved it under the hood with the air cleaner off, it shot two streams of gasoline over the carb and two arching streams fell cleanly into the secondaries... only problem was the secondaries were mechanical and did not open unless you reved past the half way on the pedal, so you could see a little pool of gas that quickly got sucked into the secondaries. I didn't seem to have any problems because of this, so I left it alone. the car was amazingly responsive, better than any car I've owned since, even better than some fuel injected cars I had. Dang thing always smelled like gas. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 19, 2005 Share Posted January 19, 2005 Back in the 1970s I had a Q-Jet on the 1972 455 SD engine in my 1966 Pontiac GTO. Mailed the carb to a guy with a small shop back east named John Lingenfelter. When he sent the carb back he called me and said, "Don't ever replace this with a Holley. A well tuned Quadrajet is better then a well tuned Holley on any street driven car." After working his magic on the Q-jet, the GTO went from sporadic 14.5s to consistent 13.2s and I won more then my share of purses at OCIR during the Wednesday night brackets. Also won a number of street races because all the "experts" thought the Q-jet was bad carb and couldn't match a Holley equipped car. Quote Link to comment Share on other sites More sharing options...
Len Posted January 19, 2005 Share Posted January 19, 2005 back in the 70's had a Qjet on my 68 olds 442 ran good for a few years then it seemed like I had to rebuild that thing nearly every month...when I eventually rebuilt my 455 engine I switched to a holley...ran better but really seemed not as good as original Q jet... I found out just a few years ago from a guy that had the same experiences he said... allot of times the problem is that the carb body including around the linkage etc. just wears out. No amount of rebuilding could change it. Made sense to me. I got to wear I bought the rebuild kit for $5 right after school...rebuilt the carb in two hours and was cruising mainstreet that night. Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted January 19, 2005 Share Posted January 19, 2005 These guys are Q-jet experts, give them a call: The Carburetor Shop 1457 Philadelphia, Unit 24 Ontario, CA 91761 909/947-7744 http://www.hotrod.com/techarticles/42590/ Quote Link to comment Share on other sites More sharing options...
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