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Post by Gasket on Apr 16, 2005 0:23:46 GMT -5
Just rebuilt the Q-jet on my 77 350. After full tuneup and timing set, it runs MUCH better than it used to, but still have a problem. It floods itself when I have the stock air cleaner (small opening) on it. Kind of solved the problem with an open element, but it still bogs when the engine is cold (and sometimes when warm, but not as bad). When it bogs, it puts out a little black smoke and makes no power. All carb settings are per rebuild kit (and service manual) specs, and this is not my first Q-jet rebuild. Help! Any ideas what might be wrong?
Thanks
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Post by 19_Chevelle_69 on Apr 16, 2005 18:37:47 GMT -5
Is the choke plate opening up fully? It should be straight up and down when at operating temperature.
Also, how did you set the idle mixture screws?
The manual/rebuild kit will likely give you a base setting, but you have to fine tune it from there...
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Post by Gasket on Apr 16, 2005 19:03:49 GMT -5
The choke plate is fully open when the engine's hot. The idle set screws are turned out 1 1/2 turns. The kit "instructions" said to turn them out 3-4 turns. It ran way too rich at that setting.
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Post by 19_Chevelle_69 on Apr 17, 2005 8:16:37 GMT -5
It sounds like your power valve may be sticking on you, or possibly a tube has dropped out of the top carb air horn. They usually need a gentle tap to seat them securely in the top carb cover. (air horn)
I have also seen where the casting at the bottom of the carb leaks fuel into the intake manifold below the throttle plates, Q-Jets are famous for it. When I do a rebuild, I take some 2 part epoxy and coat the casting plugs with enough to cover them all.
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Post by customdeluxe on Nov 17, 2005 20:00:01 GMT -5
I havent seen a Q-Jet that does not bog we used to call them QuadraBog I have seen people get the bog out of them I never realy messed with em to much
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Post by Missgoodwrench on Nov 24, 2005 14:05:27 GMT -5
I have a question about the power valve.
My 72 is acting like it isnt getting enough fuel sometimes. It has the full edlebrock performance kit and we have rebuilt the carb 4 times. This last time the tow truck driver said he though it had a blown power valve, but I was always told that only Holleys have power valves. Any idea what may be causing the loss of power and the bad gas mileage? I also noticed that the air filter has a few burn spot where it has blown through and melted the element.
Help please!!!
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Post by 19_Chevelle_69 on Nov 24, 2005 17:48:08 GMT -5
It sounds like you have more of an ignition problem by the burnt air filter. It's been backfiring.
How old is the cam? Have you checked the timing?
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Post by Missgoodwrench on Nov 25, 2005 13:28:50 GMT -5
The cam is probably 5 years old but has only maybe 20K miles on it. The motor was rebuilt right before we bought the truck in 01. We have shop receipts for everything. The timing light says it is right on, and we have replaced the coil, the dist cap, the ignition module, the regulator, and put a brand new HEI in it. We thought it might have a stuck valve in the driver side head, but after having it towed to the house it seemed to run fine, it just has no power to stay above 35 MPH. It doesnt back fire that I can tell, but there is an exhaust leak at the flange so it is hard to hear any other noise. It is also getting way bad gas mileage. It used to get about 15 MPG now we are at around 5-8.
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Post by highwaystar on Dec 22, 2005 10:47:46 GMT -5
well i had a quadrajet .. til the mechanic broke it... sooo i took itback.... gaveit to a budyy n hes gonna see if its repairible... if not i'ma use the core n grab me a new one
now i got some camaro carb that the mechanic put on nits still not idleing right .....fakin carn artist
where is the screws 4 me to tweek the carb ?
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Post by highwaystar on Dec 22, 2005 10:49:31 GMT -5
Just rebuilt the Q-jet on my 77 350. After full tuneup and timing set, it runs MUCH better than it used to, but still have a problem. It floods itself when I have the stock air cleaner (small opening) on it. Kind of solved the problem with an open element, but it still bogs when the engine is cold (and sometimes when warm, but not as bad). When it bogs, it puts out a little black smoke and makes no power. All carb settings are per rebuild kit (and service manual) specs, and this is not my first Q-jet rebuild. Help! Any ideas what might be wrong? Thanks if u got the small plastic pipe attached ..... rip it off |
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