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I need a little help. I have the speed demon 750 on my 350. I have vortec heads, the 292 comp. cam in it, and the super victor. But anyways here's the problem. When I give the car gas it just seems to have a bog in it. I guess the car just hesitates and tries dying.
I don't really know how to explain it. I've experimented with the jets a lot. I have went both up and down. Right now the jets are at 76/83. Are any of you having problems with the demon? if so what did you do to help the problem?
 

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I personally don't have any experience with the Demon carbs, but I can tell you how two of my buddies solved the problems with thiers. They sold them and bought Holley DP carbs.

I know this isn't exactly the advice you are looking for, and I am not trying to be a smart A**, but they tried everything to alleviate idle, drive and WOT issues with no success.
 

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I've found they are very sensitive to idle mixture screw adjustments.
If they're not perfect, you get a lean "tip in" hesitation. Did you get the video with yours?
A baseline is all 4 screws out 1 1/2 turns.
I was very surprised how touchy they are about that, as Holleys are not that bad.

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Don~ ZZ430DropTop
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67 RS/SS Convertible, 70 RS/Z28
 

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Crossram said it all. Do a search for Demon, you will find a lot of negative discussion. I finally got mine to run right, but it was still at least .1 slower than my Holley. I sold it.

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67 Camaro 410sb 11.63 @117.6
67 Camaro 388 12.10 @110.6
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I have a speed demon 650 with mechanical secondaries on a fast burn 385 crate motor. I took the jetting down from 70/78 to 66/74 and set the idle screws at 3/4 turn. This was after about two weeks of playing around and adjusting. The main problem was the idle (around 1100 rpm) and the jetting was too rich. At one point I did encounter a hesitation while adjusting the idle mixture screws(I learned that they all need to be set at the same amount of turns). To solve the idle problem I ended up having the secondary butterflies almost closed the whole way. Now my plugs look good and there is no hesitation and it actually idles. I called their tech line and they helped me out but it still took some playing around. Two weeks ago I was ready to buy another carb, This week I'm happy with it.
Mike
 

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i guess that is the problem with a precisely machined and built carb such as the demon- it is more touchy.there is a lot less of a fudge factor- you need to play with it to get it right.but isn't that part of the fun of this hobby- tweaking our cars to make them run better?

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1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16" IROC wheels
 
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