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Old 12-09-2003, 09:59 PM
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625 Road Demon Jr. Problems!!!!

Hi im new here and would like to know if you guys could try and help me out....Ok i got a chevy 350 its pretty stock except for a few parts like a Edelbrock Torker II intake manifold, Hooker Competion Header and a 625 Road Demon Jr. carb....When i first fired my motor it was running good....then a month later it starts acting up idleing real weird and running real rich with black smoke and a stong scent of gas out the exhaust....i tried adjusting the carb by playing with the idle mixture screws and float levels but it would still run rough and rich....now the other day i checked the oil and its diluted with gas....i have ran out of gas a few times and it takes a little cranking of the engine to get the gas to the carb....could cranking the engine over like that fill the oil with gas because i have ran out of gas a few times.....or do i have a bad fuel pump....or maybe is the carb too big for a stock motor like the one i have? if the carb is too big would putting a bigger cam help because i have a crane energizer cam and lifter set....454" lift and the duration @ .050 is 216 on intake and exhaust....if anyone could help it would be much appreciated.....THANK YOU

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Old 12-09-2003, 10:04 PM
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I think you would be better off with a dual plane manifold. The single plane doesn't have as good of metering at lower RPMs. The new cam you are talking about is small. The carb size you have right now is okay and is not the cause of your problem.

Do you use a vacuum guage to tune your carb?
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Old 12-09-2003, 10:56 PM
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no i dont have a vacuum gauge....i have just been tuning my carb on what the instrustion on the road demon jr say to do if im running rich....

also does anyone know anything about the energizer cam part # 100052 454" lift, 216 duration @.050....i got the cam and lifter set from a neighbor for 50 bucks and its brand new....so does anyone know anything about that cam like what does it sound like what kind of performance does if have for chevy 350....i know it am no big cam....if u can help me it would be appreciated....THANK YOU

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Old 12-09-2003, 11:05 PM
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That cam will give you a little more midrange and top end power. It is pretty mild and should idle well.

You should tune with a vacuum guage. Tune for highest manifold vacuum. That is the best way. What did the Road Demon instructions say?
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Old 12-09-2003, 11:49 PM
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they pretty much said adjust idle mixture screws by screwing them in, lower float bowl levels, reset butterflies and increase intitial engine timing....i did pretty much all that i set the float blow levels to the middle of the glass like they say....i adjusted the idle mixture screws by turning them in i even turned them in all the way and it still runs rich and rough....i have tried setting the timing at 8 through 14 degees btdc....i took the carb off the motor and the butterflies seem to be set right....i really dont know what else to do....thanks
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Old 12-10-2003, 12:04 AM
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Buy a vacuum guage. They are about $20. They allow you to precisely set your idle mixture. If what you said is what the techs told you then they have never worked on a carb.

Your float levels could be high also. Go to Holley's website. It will tell you how to set the floats. It would be a good idea to learn more about tuning Holleys. They are just like BGs.
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Old 12-10-2003, 12:10 AM
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i will try that thanks alot for the replys
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Old 12-10-2003, 06:32 AM
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Re: 625 Road Demon Jr. Problems!!!!

Quote:
Originally posted by Grant209
....When i first fired my motor it was running good....then a month later it starts acting up idleing real weird and running real rich with black smoke and a stong scent of gas out the exhaust....i tried adjusting the carb by playing with the idle mixture screws and float levels but it would still run rough and rich....now the other day i checked the oil and its diluted with gas....
If your engine was running fine, then suddenly it started running bad, and you haven't touched it, it doesn't sound like a carb tuning problem to me.

Do you have a fuel filter? Running out of gas means you sucked all the gas from the bottom of the tank where sediment and other crud collects. If you have a fuel filter it may be gunked up. If you don't have a fuel filter, you may have sucked some dirt and such into the carb.

AND, you have gas in your oil. That shouldn't be.
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Old 12-10-2003, 10:03 AM
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Having just gone through the eye burning rich idle, black sooty exhaust, fouled spark plugs and diluted oil myself...I have a ROAD DEMON 625cfm on my ZZ4 motor. I got great tech support from the BARRY GRANT/DEMON, online and by phone. I used the wrong carburetor for my application, but it now is tuned correctly and runs great. I suggest you try that to see if your JR. can be tuned for your application.
I advanced my timing in my application as you've tried to do. I tuned my DEMON with a vacuum gauge as suggested. Two other places that they will suggest you look at if everything else is adjusted correctly.
First, your secondary transition slot may be open to the .020 that they set it at from the factory. That will lead to the symptoms that you describe. I closed mine off entirely. The very small allen screw that closes off the secondary butterfly transition slot is accessible on the passenger side of the carburetor, under the vacuum pod. It's a black set screw on the secondary throttle shaft.
Second, the air bleeds MAY have to be enlarged from stock. (.059 or .063?) Do that ONLY after all other remedies have not improved the condition.
I had my DEMON off so many times I was ready to toss it. Now, I love it...like any other carburetor it needs to be fine tuned.
The suggestion about checking for a fuel filter obstruction is excellent since this is a recent problem after it was running ok for you. That crud could have made its way into the needle and seat, which is holding your float(s) open and causing the rich idle.
All adjustments should be done with the motor warmed up per every carburetor manufacturers instructions.
Also, you shouldn't be running more than 5.5-6# of fuel pressure through your carburetor or the floats will not be controlled by the needle and seat. A pressure regulator and gauge will aid in maintaining pressure.
Here's the DEMON site http://www.barrygrant.com/
If you click on "products", then "carburetors", then look in the list on the right side, click on "tuning tips"... you'll find their step by step instructions on what to do next if you experiance certain symptoms. It is very detailed.

Last edited by hotwheels55; 12-10-2003 at 12:21 PM.
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Old 12-10-2003, 01:12 PM
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Which carb to use?

I think I'll stick with my Edelbrock carbs. When BG says that carb is made for a 350hp engine thats exactly what they mean. Might want to consider the BG 2brl carb. The stock sbc 350 will run nicely on it. I don't know that even after all your planned mods you will have enough HP for that carb?? I have a stroked 350 with as 400 crank, roller cam and roller rockers, flattop pistons and 2.05" ported and polished heads , electric water pump and 3" headers and I don't know which BG carb to run???


Todd


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Old 12-10-2003, 02:07 PM
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The nice thing about EDELBROCK carburetors is their relative simplicity. You take them out of the box and with little or no tuning they work just fine for almost every application.
I've said before on carburetor topics that EDELBROCK has always been my choice for just that reason. I was not and am still not in comparison to other knowledgeable members here, a carburetor expert. Tuning a HOLLEY or a DEMON takes practice and great patience. I certainly have the experiance.
The DEMON carburetor offers alot, not only in appearance but performance. Someone mentioned this in another thread about DEMON carburetors...forget everything you know about tuning a HOLLEY and read the DEMON instructions. That is so true.
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Old 12-10-2003, 06:59 PM
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Re: Re: 625 Road Demon Jr. Problems!!!!

Quote:
Originally posted by mstngjoe
If your engine was running fine, then suddenly it started running bad, and you haven't touched it, it doesn't sound like a carb tuning problem to me.

Do you have a fuel filter? Running out of gas means you sucked all the gas from the bottom of the tank where sediment and other crud collects. If you have a fuel filter it may be gunked up. If you don't have a fuel filter, you may have sucked some dirt and such into the carb.

AND, you have gas in your oil. That shouldn't be.
i emailed barry grants tech people and they said something to that effect too....they said if it was running great at first something must be clogging the carb....they told me pull it apart and clean the carb with carb cleaner and then go from there....and yes i am running a fuel filter....thanks for the advice i think i will buy a new filter and clean out the carb then go from there....

Quote:
Originally posted by hotwheels55
Having just gone through the eye burning rich idle, black sooty exhaust, fouled spark plugs and diluted oil myself...I have a ROAD DEMON 625cfm on my ZZ4 motor. I got great tech support from the BARRY GRANT/DEMON, online and by phone. I used the wrong carburetor for my application, but it now is tuned correctly and runs great. I suggest you try that to see if your JR. can be tuned for your application.
I advanced my timing in my application as you've tried to do. I tuned my DEMON with a vacuum gauge as suggested. Two other places that they will suggest you look at if everything else is adjusted correctly.
First, your secondary transition slot may be open to the .020 that they set it at from the factory. That will lead to the symptoms that you describe. I closed mine off entirely. The very small allen screw that closes off the secondary butterfly transition slot is accessible on the passenger side of the carburetor, under the vacuum pod. It's a black set screw on the secondary throttle shaft.
Second, the air bleeds MAY have to be enlarged from stock. (.059 or .063?) Do that ONLY after all other remedies have not improved the condition.
I had my DEMON off so many times I was ready to toss it. Now, I love it...like any other carburetor it needs to be fine tuned.
The suggestion about checking for a fuel filter obstruction is excellent since this is a recent problem after it was running ok for you. That crud could have made its way into the needle and seat, which is holding your float(s) open and causing the rich idle.
All adjustments should be done with the motor warmed up per every carburetor manufacturers instructions.
Also, you shouldn't be running more than 5.5-6# of fuel pressure through your carburetor or the floats will not be controlled by the needle and seat. A pressure regulator and gauge will aid in maintaining pressure.
Here's the DEMON site http://www.barrygrant.com/
If you click on "products", then "carburetors", then look in the list on the right side, click on "tuning tips"... you'll find their step by step instructions on what to do next if you experiance certain symptoms. It is very detailed.
thanks for the advice it sounds like you went through just what im going through....i have not tried to adjust the secondary butterflies yet so think im going to try that one that might be one of my problems....thanks

Quote:
Originally posted by tm454
I think I'll stick with my Edelbrock carbs. When BG says that carb is made for a 350hp engine thats exactly what they mean. Might want to consider the BG 2brl carb. The stock sbc 350 will run nicely on it. I don't know that even after all your planned mods you will have enough HP for that carb?? I have a stroked 350 with as 400 crank, roller cam and roller rockers, flattop pistons and 2.05" ported and polished heads , electric water pump and 3" headers and I don't know which BG carb to run???


Todd


Rat Rods Rule!
i have had few people tell that carb was too big for my engine also....i email barrry grants tech people and gave them my engine info and they said carb is not too big for my application....so i dont know....but thank you

Last edited by Grant209; 12-10-2003 at 06:59 PM.
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Old 12-10-2003, 07:01 PM
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It isn't too big. It just isn't adjusted properly.
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Old 12-10-2003, 07:05 PM
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I can't believe the information one can get on this forum. You people ROCK with intellegence. I love this site. Hope you figure your problem out. Let us know.
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Old 12-10-2003, 07:14 PM
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yeah i been coming to this site for a day now and im loving it....people just responding one after another to help some guy they dont even know out....you can tell you guys really love cars....i appreciate all the advice....THANK YOU
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