Need suggestions Quick fuel Carb

[pjc360]

I have a quick fuel super street series 680cfm vaccum secondary carburetor on my 300hp crate 360 magnum. I live 4000 feet above sea level and I don't have a wideband, so tuning this carburetor has been a task, all I have is plus to look at. The other night was the first time I noticed my hedders glowing red in the dark. The rpm range was 2000 to 2500 rpm. I leaned down my idle feed restrictors and that didn't do anything, the hedders were still glowing red at night at 2000 to 2500 rpm. So I started looking at other things being the cause, I sat there under the hood and held the carb open at 2000 to 2500 rpm and I noticed the boosters were dripping quite a bit of fuel.
I also noticed this is when the hedders would start glowing and the engine would sound like crap, sounded like it was loading up.
So I looked at the high speed air bleeds, they were .028's, which I am told is a very rich high speed air bleed, I drilled them out to .039 and it still did it. So I took out all 4 high speed air bleeds and started it and held the throttle at 2000 rpm and I noticed the last 2 hedder pipes by cylinder 6 and 8 were slightly showing red but nothing like it was and it sounded a lot cleaner. This indicates to me that my idle feed restrictors are a bit rich, since it did this with the high speed air bleeds completely removed. my idle feed restrictors are .030 right now and I ordred 4 .028 idle feed restrictors, they will be here tomorrow.
So tomorrow I am going to install all 4 .028 idle feed restrictors, now I need to know what I should do about my jets and high speed air bleeds. Since it was still way too rich at 2000 rpm with the .039 high speed air bleeds and 65 main jets I was thinking about dropping the main jets 2 sizes and trying some .045 high speed air bleeds. Am I on the right track here?

[shiftbyear]

I would call quick fuel and ask them what a good starting point for your altitude. They should know their carbs better than anyone. Timing and spark plug heat range can change things also. Vacuum leaks can also drive you nuts. Good luck.

[My427stang]

Have you checked your timing curve?

[1972ho]

You should put the carb back to the way it was when you first got it ,And then make sure your fuel level is normal (1/2) way in the sight glass,check and set fuel pressure to 6.5 to 7.0 check for vacuum leaks and all the small ports on the carb plugged,turn out idle mixture screws at least 11/8 open and then start the engine and check the timing.Because man QF makes a pretty good carb. you should not have be making the changes that you are making I have a SSR 780 VS carb and have not had to do anything to it tweak on it.And normally when the exhaust header gets red hot there are vacuum leaks pulling extra unmetered air to the engine causing you have to ad more idle fuel to keep it running.

[jmarkaudio]

Glowing headers is usually insufficient initial timing, what is your timing specs?

[pjc360]

Fuel pressure is at 6 pounds, timing is 15 degrees initial 33 degrees total. Verified balancer with a piston stop.
Spark plug is ngk zfr5f11's. Plug wires are good. No vaccum leaks. I have checked for vaccum leaks. Intake is brand new and so are the gaskets.
Not trying to sound arrogant but I wouldn't have posted the question if I hadn't already checked all of this stuff.
And this carb is a pretty advanced carb with all the changeable air bleeds and restrictors and my engine is fairly mild and I am at 4000 feet above sea level so that changes things quite a bit.
Float level is set correctly on both bowls. I will call quick fuel and ask them what they think a good starting point would be, in my experience they don't really know because every engine is different. I am on the lookout for a wideband right now and that would help tremendously in dialing this carburetor inn. But for now all I have is plugs to look at and hedders at night lol.

[pjc360]

Another thing that indicates to me that the hedders glowing is fuel related and not timing related is because when I remove the high speed air bleeds and fire it up and hold the throttle at 2000 to 2500 rpm the glowing hedders stop.

[BigBro74]

"I sat there under the hood and held the carb open at 2000 to 2500 rpm and I noticed the boosters were dripping quite a bit of fuel."

this to me sounds like your most likely issue.
I had one the other day that the o-ring on a needle and seat would leak after it sat for the winter and did this, but other float/ needle seat issues can do this as well as power valve issues...........
I would say you have a simple mechanical issue with the carb function more than a calibration issue. go back to original calibration and make absolutely sure all the mechanicals in the float and power valve(s) are working right, its not too difficult. JMO Jason

[BigBlocksOnTop2]

Another thing that indicates to me that the hedders glowing is fuel related and not timing related is because when I remove the high speed air bleeds and fire it up and hold the throttle at 2000 to 2500 rpm the glowing hedders stop.

Rework the timing curve to get around 26° at idle and the rest in at 2500rpm's. Alot of fuel is burning in the headers. Light the fire sooner (26°) at idle and watch the rpm's go up. Then adjust the idle speed screws along with the idle fuel screws....it will be a happier engine.

[pjc360]

well technically I do have additional timing because I have my vaccum advance plugged into the manifold vaccum port.
I have it set at 15 degrees initial and 33 degrees total and my vaccum advance adds another 15 degrees of timing at idle. So at idle I have 30 degrees of timing with the initial and vaccum advance timing.
This carburetor is brand new, it doesn't even have 5 hours of run time on it yet. The power valve is brand new so is the gasket and I know it's tight, I double checked it.
Could the needle and seat be too large? On the card that came with this carburetor that tells you what size everything is it says the needle and seat is 110.
I don't have much experience with needle and seat sizes, what does a smaller and larger size do? And could this contribute to the boosters dropping fuel too soon?

[BigBlocksOnTop2]

Float level way too high makes it easier for the main circuit to come in. Put the float level at the bottom of the bowl screws(with the engine running)on the primary and secondary. You probably need to rock the car to get excess fuel out of the bowls. Adjust the levels low,then adjust until fuel just starts to spill from the bowl screws. At idle you need more than you think for ignition timing on a performance engine. The extra fuel will make the headers glow. This extra fuel is completing its burn in the headers. Float level, a non ruptured power valve, the correct power vlv. rating, a good not crushed power vlv. gasket are all part of the equation to making it all work.

[JoePorting]

I'd replace the power valve again. Whenever I had issues like you're having, it turned out to be the power valves. When a power valve leaks or is blown, extra fuel dumps into the main wells causing a rich condition and fuel also leaks down the power valve vacuum port. Both of these situations cause an ultra rich condition like what you have. Buy a few more power valves. Every time your motor back fires, figure that the power valves are going to have to be replaced.

I'd also put the air bleeds back to where they were when you got it out of the box. Drilling a carb is a bad idea unless you really know what you are doing.

[rp930]

I live at 6400' and only moved 2 jet sizes on my AED carb. I agree with the others this is not a calibration issue.

[pjc360]

It was an overly rich condition causing the issue. I finally gave up and called quick fuel and told him what my settings were and he said it all sounded about right except the high speed air bleeds, he said to go back to .028 hsab's. I told him engine loads up around 2000 to 2500 rpm while sitting and holding the throttle and I told him I first discovered the issue with the fast idle on at night, his answer was I hear this all the time when people are breaking in cams wile running our carbs and from people who have there fast idle turned up to high. He said back off your fast idle screw a little until it stops, he said your pulling on the mains at fast idle and are loading the engine up. He said when your running down the road your putting a load on the engine and that won't happen, but when your just sitting there in park there is no load on the motor and that's going to happen.
Not too sure how I feel about this answer, but I did turn the fast idle down and my hedders don't glow red anymore while the fast idle is on, do you still recommend I re-work the distributer to get more initial timing, say like 18 to 20 degrees? Or am I ok running 16 degrees initial and 34 total like I am right now, I also run vacuum advance off of the manifold vacuum port which gives me another 14 degrees of timing at idle. I went back down to .033 hsab's and that's seems to be working alright, I will know for sure soon when I get my wide and o2.