got a 650 demon, got questions..
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Joined: Nov 2007
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From: Manama
got a 650 demon, got questions..
Hi, I've done a search before I came to ask this question about the demon..
in the BG manual, it is written that the carb's should run the best at 1 to 2.5 turns out, but mine seems to give the best vacuum at 3/4, but there is no way to get the idle below 900RPM, I read from Lars that the 650 idles the best at 3/4 turn but then why did they write that it should run the best from a full turn to arround 2.5?
when I keep it at 3/4, I get a lot of detonation (which I didn't get with my previous holley 650) when I floor it. the timing was set to 10 degrees as the mechanic told me, I even tried to turn the destributor clockwise a bit but nothing changed.
I think I have to close the throttle plate slightly to lower the RPM, but which screw is the one I have to adjust from? any picture available that shows it?
thanks.
in the BG manual, it is written that the carb's should run the best at 1 to 2.5 turns out, but mine seems to give the best vacuum at 3/4, but there is no way to get the idle below 900RPM, I read from Lars that the 650 idles the best at 3/4 turn but then why did they write that it should run the best from a full turn to arround 2.5?
when I keep it at 3/4, I get a lot of detonation (which I didn't get with my previous holley 650) when I floor it. the timing was set to 10 degrees as the mechanic told me, I even tried to turn the destributor clockwise a bit but nothing changed.
I think I have to close the throttle plate slightly to lower the RPM, but which screw is the one I have to adjust from? any picture available that shows it?
thanks.
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Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Your idle mixture screws could make your motor run fine anywhere for 1/2 to 2 1/2 turns there is no magic number, if you don't have a O2 wideband then you hook up a vacuum gauge and disconnect the vacuum advance and turn all screws 1 1/2 turns out and then move them the same amount in or out until you get the highest vacuum.
Next you need to buy or borrow a dial back timing gun to see how far off your timing is. If you say it won't idle below 900RPM this suggests to me that your vacuum is retarded and you are compensating by setting the curb idle higher
Can't say how the idle mixture screws are making your engine detonate but what you need to do is start from the beginning. Take the carb off and look at the the transition slots they should be square or about 40 thou on all four. Next buy the book " How to tune a Holley" or you can go to this link and get a PDF file for tuning your specific carb
http://www.barrygrant.com/pages/manuals.aspx
Next you need to buy or borrow a dial back timing gun to see how far off your timing is. If you say it won't idle below 900RPM this suggests to me that your vacuum is retarded and you are compensating by setting the curb idle higher
Can't say how the idle mixture screws are making your engine detonate but what you need to do is start from the beginning. Take the carb off and look at the the transition slots they should be square or about 40 thou on all four. Next buy the book " How to tune a Holley" or you can go to this link and get a PDF file for tuning your specific carb
http://www.barrygrant.com/pages/manuals.aspx
Le Mans Master
Joined: Jun 2008
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From: Rockledge FL
Does this model have the idle eze feature? Also did you set the rear throttle blades? 10 degrees isn't much. Mine idles at 20 with the advance plugged in and stops at 36 once it hits 3000rpms. Make sure your timing is on before you try to set the carb.
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From: Manama
I wil check the timing, even when the mechanic said that he checked it with a timing gun, I'm now also having an issue with the headlights/wiper door opening and closing like crazy, maybe be due to low vacuum, or simply I was cursed by putting on this demon! what is happening to my vette is really insane.
and I read about people complaining about the electric choke and removing them eventually, is it that bad? mine works but shoots up to 2000 RMP @ startup which is stupid much isn't it???
and I read about people complaining about the electric choke and removing them eventually, is it that bad? mine works but shoots up to 2000 RMP @ startup which is stupid much isn't it???
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i wonder if you have a vaccum leak look at the gasket under the carb, maybe try doubling them up.
I removed my electric choke, those carbs run so rich anyway its hard to imagine that you need it. just feather it for the first 30- 45 seconds when its really cold and after that it should be fine, unless its really cold where you are
I removed my electric choke, those carbs run so rich anyway its hard to imagine that you need it. just feather it for the first 30- 45 seconds when its really cold and after that it should be fine, unless its really cold where you are
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From: Manama
yeah, cold.. well minimum of last 3 days was 29 degrees celcius, today it is 40C! 
I need an off day to have all the time to do this check, coz it is redicilous with this vacuum, but the good thing is that the wiper moved yesterday after the door opening, while it never worked before
I need an off day to have all the time to do this check, coz it is redicilous with this vacuum, but the good thing is that the wiper moved yesterday after the door opening, while it never worked before
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From: Manama
ok here is the deal, the vacuum part has nothing to do with the carburetor, after some troubleshooting last night I found out tha the relay switch of the wiper door was having a broken tube, which caused a leak, so when I open the wiper door the vacuum is restored since it sucks air from the other tube which is not broken.
I guess that is a reason that causes my car idle higher after putting everything back togeather.
will check again...
I guess that is a reason that causes my car idle higher after putting everything back togeather.
will check again...
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