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#1
10-02-2005, 03:35 PM
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how can i tell what size q-jet i have?
how can i tell what size carb i have on my engine. what size q-jets were/are available. my engine is a '73 model 400 but i can't be certain the carb is the original. where can i go to get this info.
__________________
 "Second place is the first loser""That's no oil leak....that's just sweat from all that horsepower." |
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#2
10-03-2005, 10:36 AM
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Give us the numbers off the carb.
__________________
Badder than old King Kong And meaner than a junkyard dog -Jim Croce |
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#3
10-03-2005, 11:27 AM
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Here is pictures of both 750cfm and a 800cfm...You can see the ring in the primary of the 750 which is not on the 800 version
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#4
10-03-2005, 08:55 PM
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where are the numbers located?
is that some kind of restrictor ring?
__________________
"Second place is the first loser""That's no oil leak....that's just sweat from all that horsepower." |
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#5
10-04-2005, 12:35 AM
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There are two basic Q-jet castings, the "750 cfm" and the "800 cfm". The only real difference is in the size of the primary venturi. The primaries were opened up a bit on the 800s to get the extra flow. Without two carbs to compare side-by-side it can be difficult to tell whether you're looking at the smaller or larger venturis, but there is one surefire way - pull the carb, turn it upside down and open the primary butterflies. The 750 has smooth venturi walls all around the booster rings. The 800 has a "bump" in the wall of the venturi adjacent to the booster rings.
The numbers are on the driver's side of the carb on a flat between the primary and secondary side of the carb. Remove the aircleaner and get in there with a flashlight and you'll find them.
__________________
---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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#6
10-06-2005, 07:00 PM
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the numbers that i found were stamped on two lines, the first line reads:17056259
the second is: 0866 ASC
__________________
"Second place is the first loser""That's no oil leak....that's just sweat from all that horsepower." |
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#7
10-07-2005, 08:13 PM
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76 olds 350 w/AC--800cfm.
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#8
10-08-2005, 04:54 AM
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Very few, if any, of the "M", as in Modified, Q-jet models, 1975 and later is flowing the full 800cfm as the casting allows.
For full 800 cfm flow, the secondary airvalves opening needs to be adjusted to open 1.38" , measured from the rear ridge of the open valve to the back of the choke housing. Also check that the sec. throttle plates are open 90 degrees +- 5 degrees. |
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#9
10-08-2005, 10:32 AM
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If you ever want to look up a Q-jet number, just type it into Google search. Never fails for me.
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