Float levels
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Float levels
I know that float levels can be adjusted but what is the advantage of changing the level in bowl. My Demon was suppose to be set at the factory for middle of the window but it was actually all the way to the top. I adjusted it to the middle.
Lars says to start with them at the bottom of the window. I know when you hit the throttle the level drops. In my case to the bottom of the window. Then recovers when you let off. I'm just trying ot understand what changing the level gives you. It seems that too low of level would choke off the fuel supply but I'm just guess from my observations.
Can anyone dumb this down for me? Thanks,
Steve
Lars says to start with them at the bottom of the window. I know when you hit the throttle the level drops. In my case to the bottom of the window. Then recovers when you let off. I'm just trying ot understand what changing the level gives you. It seems that too low of level would choke off the fuel supply but I'm just guess from my observations.
Can anyone dumb this down for me? Thanks,
Steve
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,443
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
In actuality if the float is opening and closing the needle and seat, the fuel level should never change unless the demand is so great that the seat valve can't keep up. Then you might look at minor fuel pressure increases or larger needle valve diameter. I used to run the great big .110 titanium needle valves with 5 or less PSI
the big deal about bowl level is:
Consistency! To get a constant A/F ratio you have to have a constant flow rate out of your jets and metering circuits. A slightly higher fuel level will have just an hair more pressure than a lower level bowl. So without changing anything you have a richer mixture.
I have a Demon and I run mine at mid sight glass. Then I have road racer friends that run it lower to prevent slosh out of the bowl vents.
the big deal about bowl level is:
Consistency! To get a constant A/F ratio you have to have a constant flow rate out of your jets and metering circuits. A slightly higher fuel level will have just an hair more pressure than a lower level bowl. So without changing anything you have a richer mixture.
I have a Demon and I run mine at mid sight glass. Then I have road racer friends that run it lower to prevent slosh out of the bowl vents.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Well when I say it drops when I hit the throttle I mean HARD throttle. Like 3500-4000 RPM punch.
Under normal, steady throttle increase it stays pretty level.
I also had to lean it out a bit because I couldn't stand the damn fumes in he garage but now it want to idle higher. I have to make it richer to decrease the idle. The idle screw isn't even touching the throttle.
Under normal, steady throttle increase it stays pretty level.
I also had to lean it out a bit because I couldn't stand the damn fumes in he garage but now it want to idle higher. I have to make it richer to decrease the idle. The idle screw isn't even touching the throttle.
Last edited by SargeZ06; Sep 20, 2007 at 06:24 PM.
Pro
Joined: Jun 2002
Posts: 538
Likes: 7
From: Johnsonville Wi
El Samo
Can Am, my son has exactly the same problem with the idle (Demon 650 on a ZZ3). The lowest idle he can get is 1,000 rpm and to get there he has to set his idle mixture screws way out of whack.
He's in contact with Demon about it and I'll let you know if he gets it resolved.
Daffy
He's in contact with Demon about it and I'll let you know if he gets it resolved.
Daffy
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
I have a ZZ383 with a Speed Demon 750.
Let me know what they say. I have adjust the Ez-Idle and see if can set the idle screws back to a little rich for the idle and use the Ez-Idle to lean it up a bit with some more air. It like drilling a hole in the blade to allow more air.
Steve
Let me know what they say. I have adjust the Ez-Idle and see if can set the idle screws back to a little rich for the idle and use the Ez-Idle to lean it up a bit with some more air. It like drilling a hole in the blade to allow more air.
Steve
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You have to set your throttle blades at .020. If your idle speed is way to high you are bleeding too much air through the idle EZ.
You have to install a fine wire in the idle fuel port to restrict the fuel flow. Look up some posts on how to do it.
You have to install a fine wire in the idle fuel port to restrict the fuel flow. Look up some posts on how to do it.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
Unless you have a huge cam, close the IdleEZ completely - you don't need it. Set initial idle speed by setting both primary and secondary idle speed screws so that .020" of the transition slot is exposed below the throttle blades. Then, fine-tune idle speed by equally adjusting primary and secondary idle speed screws. If you cannot kill the engine by backing out both idle speed screws you have a vacuum leak somewhere. You do not adjust idle speed with the idle mixture screws or using mixture as a tool to regulate idle speed.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
Well I think found the issue. I noticed sometime after punching the throttle I would get a good low idle and sometimes I would get a high. So I diconnected the throttle cable and it returns to a low idle everytime. Looks like my throttle cable is sticking at the very end of the travel. I'll adjust another 1/32 of slack to the cable end where it connects to the throttle.
Oh backing out the screws definately kills the engine.
LARS on another note what do you think of 21 degree of initial timing and 36 all in?
Thanks.
Steve
Oh backing out the screws definately kills the engine.
LARS on another note what do you think of 21 degree of initial timing and 36 all in?
Thanks.
Steve
Last edited by SargeZ06; Sep 21, 2007 at 11:30 AM.
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Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
I found a thread that says that 12-24 initial is good to go.
http://forums.corvetteforum.com/show...iming+how+high
I didn't adjust the EzIdle so it is still all the way in. Once I removed the throttle cable I set Idle speed screws at 1 1/2 out and then set idle with idle screws. Then fine tuned idle speed screws from there on the 4 corners equally. I need to road test but it seems pretty smooth.
http://forums.corvetteforum.com/show...iming+how+high
I didn't adjust the EzIdle so it is still all the way in. Once I removed the throttle cable I set Idle speed screws at 1 1/2 out and then set idle with idle screws. Then fine tuned idle speed screws from there on the 4 corners equally. I need to road test but it seems pretty smooth.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,443
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,095
Likes: 5
From: Oldham County Louisville, KY
I backed it down to 15 initial and 28 all in and it stumbles off idle pretty bad. If I bump it back up to 34-36 it responds wells and doesn't stumble. At the higher timing it also idles higher. Transition slot is set to .020 and mixtures screws are out 1 1/2 turns.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
.020" is a starting point and a maximum. If you have to set the idle to show more than .020", your idle circuit will not respond correctly. Reduce idle speed as needed from the .020 intial starting point by reducing both primary and secondary idle speeds evenly.
Lars
Lars