BuickNut Posted April 8, 2002 Share Posted April 8, 2002 I have a '73 Century GS Stage 1 with a 455 engine and 4 bbl (curently has a Holly 850 double pumper with mechanical secondaries, that was "built down" as it was too much for the stock engine to handle), and bought an 850 cfm Rochester QuadraJet 4 bbl carb from a non-GS Stage 1 vehicle (probably a 455 engine equiped full size cruiser is where it came from ).....what reubild kit would it take to bring it up to being what the stock engine needs ? Or would there even be any difference between the carbs between a stock GS Stage 1 QuadraJet and one from a 455 luxo-cruiser ? Thanks. Link to comment Share on other sites More sharing options...
rocketraider Posted April 8, 2002 Share Posted April 8, 2002 Can't help on the carb without knowing some of what's in it, but you'd have surely melted in the Charlotte car corral this weekend. One of the 8 1973 Stage 1 4-speed cars was for sale, with original car order and window sticker. Dark met blue, white gs decals, black canopy vinyl roof. A striking car. Striking price too, but it was a beautiful restoration. Link to comment Share on other sites More sharing options...
Guest Posted April 8, 2002 Share Posted April 8, 2002 Give us the # on the carb, That will shed some light on weather it is a 750 or 800 CFM carb. Buick 455 carbs from 71 and up were 800's. The 800's have visibly larger primary venturis and are jetted richer. The Buick 455 can easily take an 850 Holley. If you have a stock setup, the mechanical secondaries will be too much. The Q-jets air valve secondaries effectively size the carb to the engines air requirement. Link to comment Share on other sites More sharing options...
BuickNut Posted April 9, 2002 Author Share Posted April 9, 2002 I'll check out the part numbers when I get home tonight and get back to you...... Link to comment Share on other sites More sharing options...
NTX5467 Posted April 10, 2002 Share Posted April 10, 2002 A carb rebuild kit will not affect the existing calibration of the carb, just the gaskets, needle and seats, accel pump, and such that you need to put it back together when you take it apart.<P>The 800cfm Q-Jets have a 1.50" primary throttle bore instead of the 1.375" throttle bore of the regular ones--a visible difference. All Q-Jets have 2.25" secondaries, but the air valves on the newer versions will not open all of the way so the air flow total is restricted to more like 650cfm.<P>Enjoy!<BR>NTX5467 Link to comment Share on other sites More sharing options...
BuickNut Posted April 10, 2002 Author Share Posted April 10, 2002 The part number that I found on the carb (which I hope is the correct one...) is as "7043240 LA 3292" if that makes any sense. I found it on the middle section of the carb, vertically stamped. <P>I'll also check out the size of the bores as well...... Link to comment Share on other sites More sharing options...
Guest Posted April 10, 2002 Share Posted April 10, 2002 7043240 is a '73 QJet for a regular 455 w/AT. That is what is on my 225. Originally came with L hanger and CT secondary rods. You'll want to change the secondary rods as the CTs are on the low side of performance and maybe the hanger depending on what you are looking for. Link to comment Share on other sites More sharing options...
Guest Posted April 11, 2002 Share Posted April 11, 2002 Yes,that is a 73-455 carb, an 800 CFM unit. The throttle bore on the primary side is 1 3/8" for all Q-jets. The difference is in the largest of the 3 venturis, 1 3/32 for the 750's, 1 7/32" for the 800's. That carb should have .073 main jets with .049" primary rods, and CT secondary rods (.0774 power tip-change these). Look for CV rods, GM part#7045984, .0527 power tip- these came on stage1 carbs. Stage1 primary jets were .075 with .051 rods. Hope that helps. Link to comment Share on other sites More sharing options...
BuickNut Posted April 11, 2002 Author Share Posted April 11, 2002 Thanks alot folks for your help. While the Holley does work well (before the car was put in storage that is...), I am seriously thinking about changing back to the old Q-Jet. I know (think ??) that due to the smaller primaries, I will get better gas milage, and with the "beer can" secondaries, won't sacrafice performance and still get that "kick in the butt" when I throw her down a gear and put my foot to the floor. I'm going to rebuilt the carb per the recommendations brought up here.......can't thank you enough Link to comment Share on other sites More sharing options...
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