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Old 06-30-2009, 08:00 PM
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What are some causes of fuel burning rich?

I have a 84 Cutlass with a 383 stroker, don't have all the internal info but it has a demon 650 carb, performer rpm intake, mild comp cam, dart heads, 350 trans, 8.5 10 bolt with 3:73 gears. Haven't been able to road test yet because the body is not completely together. But starting it up in the garage, has my eyes burning to the point where I can't stand it.

I was told that my jets were too large. I removed the float bowl to see what size jets and they are 70's in the front. I was told to replace with size 66 jets. Could this be the problem? Or are there other factors that could cause this?

Also, I reinstalled the distributor yesterday, got the #1 piston to tdc and the rotor pointed to the #1 wire. The front float bowl was full and the rear was half full. I'm assuming I was flooding the engine. It wouldn't start unless I held the throttle wide open while turning the key. Thanx in advance for any and all suggestions

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Old 06-30-2009, 08:13 PM
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I wouldnt drop to 66s i would go to 68s and try that dont want to drop to much at one time it really should be able to handel the 70s but pretty easy swap. sounds like you need to get the floats set right also what do you mean when you say full and half full. They both need to be at the bottom of the site glass. Someone else on here may have better info on the jet sizes. Cole
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Old 06-30-2009, 08:32 PM
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The floats were full due to me pressing the accelerator while trying to get the engine to fire. The timing was off. I got that straight. Now the engine seems to be flooded and will only fire with the throttle held wide open. I looked in the sight glass and the front bowl was to the top of the glass while the rear was at the middle of the glass. After I crank it and it doesn't fire, I can hear the gas dripping in the carb, sounding like a small fountain.
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Old 06-30-2009, 08:40 PM
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I would look at float levels first. If ok, look at your inlet seat it may be hanging open.
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Old 06-30-2009, 08:43 PM
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I would get the floats set proper first should be at the bottom of the site glass, and i would pull the plugs also your going to need to replace them more than likely. Cole
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Old 06-30-2009, 09:12 PM
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And if its dumping that much gas you better change the oil to. More than likely you got gas in your oil from all the flooding. JMO. Cole
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Old 06-30-2009, 09:40 PM
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Fuel pressure too high. Regulate it to 5 psi....5psi....5psi....5psi....5psi....5psi. More pressure will not make more horsepower, it will only cause you tuning problems......5 psi....5psi....5psi
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Old 06-30-2009, 10:33 PM
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I just put new plugs in before I re-installed the distributor. I planned on changing the oil soon, guess I'll do it 2maro. How do I set/adjust the floats? I believe the carb was installed as is out of the box. There is no regulator on there now, just an inline filter. I've been wondering lately if I needed a regulator or not on a mechanical pump.
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Old 07-01-2009, 08:43 AM
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Make sure your throttle blades are not open to far at idle, this will cause the main metering system to start and cause a rich mixture .Usually .040 of the idle slot should be exposed no more.
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Old 07-01-2009, 10:53 AM
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Quote:
Originally Posted by labreejr
The floats were full due to me pressing the accelerator while trying to get the engine to fire. The timing was off. I got that straight. Now the engine seems to be flooded and will only fire with the throttle held wide open. I looked in the sight glass and the front bowl was to the top of the glass while the rear was at the middle of the glass. After I crank it and it doesn't fire, I can hear the gas dripping in the carb, sounding like a small fountain.

Accelerator position will not effect fuel level. You level is to high and you probably have raw fuel dripping into the carburetor. Fix the fuel level first and go from there. The only things that effect fuel level are the float level or a bad needle and seat
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Old 07-01-2009, 02:53 PM
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Quote:
Originally Posted by T-bucket23
The only things that effect fuel level are the float level or a bad needle and seat
Chet, with all due respect to you, a brand new needle and seat and a properly adjusted float level will not prevent excessive pressure from blowing fuel past the needle and seat and flooding the motor. 5psi....5psi....5psi....5psi....5psi
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Old 07-01-2009, 03:14 PM
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Quote:
Originally Posted by techinspector1
Chet, with all due respect to you, a brand new needle and seat and a properly adjusted float level will not prevent excessive pressure from blowing fuel past the needle and seat and flooding the motor. 5psi....5psi....5psi....5psi....5psi
Yup I agree, I was talking about the carb itself. The fuel pressure does also need to be under control as well
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Old 07-01-2009, 04:22 PM
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too rich

sounds silly but it could have junk in the needle valve,most mechanical pumps don`t over pressure the needle and seat,but check every thing the other fellows have suggested. I`ve had other kinds of valves have machine chips in them right out of the box . Good luck
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Old 07-01-2009, 10:36 PM
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needle and seat problems?

I had some troubles with my Road Demon Jr. - and it seemed to be a simple float adjustment - but it wouldn't stay stable. Since it was a new one I figured I'd strip it and find some leftover gunk in there from manufacture - looked clean. Put in a set of new set of needle and seat assemblies. Still no stability. After lots of swearing and adjusting I was convinced by a (racer) friend to get rid of the Viton (rubber) needle and seat assemblies and use larger orfice STEEL needle and seat assemblies. Instant solution - don't seem to cause any problems of their own.

The current "flavor " of gas we are getting - doesn't seem to mix well with the old Viton needle and seat set-up - that always worked before.
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Old 07-03-2009, 02:39 PM
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Quote:
Originally Posted by GREENBIRD56
I had some troubles with my Road Demon Jr. - and it seemed to be a simple float adjustment - but it wouldn't stay stable. Since it was a new one I figured I'd strip it and find some leftover gunk in there from manufacture - looked clean. Put in a set of new set of needle and seat assemblies. Still no stability. After lots of swearing and adjusting I was convinced by a (racer) friend to get rid of the Viton (rubber) needle and seat assemblies and use larger orfice STEEL needle and seat assemblies. Instant solution - don't seem to cause any problems of their own.

The current "flavor " of gas we are getting - doesn't seem to mix well with the old Viton needle and seat set-up - that always worked before.
Excellent post. Thank you.
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