dominator tuning
07-13-2015, 05:05 PM
#11
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Did you buy these new or used ? If used, what application where they for ?
07-13-2015, 05:45 PM
#13
i did buy them new this yr at 2.5 turns yes it does still stall seems like after 2 turns no real effect i can say this though it need 2 turns to stay running long enough so that i can catch it with the throttle lever and keep it going once in gear i can idle it down to 600rpm no problem it seems like its the initial load of putting it in gear i can also hear the engines loaded up when i go to get on plane like there loaded up i go to 25-2800 to get the boat on plane then u can hear em clean out and they rev to like 32-3500 it not blow out there got to be a way to make these things work
07-13-2015, 06:18 PM
#14
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I'd talk to them and see why they think it needs 3 circuits. Some people like 3 circuits and many don't.
Seems the smaller motors are better with the intermediate circuit because their airflow isn't great enough at low to mid rpm to pull enough fuel from the boosters.
Big cids, like yours, don't really have this problem.
I'm no carb guru, thus why I would talk to AED. They have built many succesful carburetors.
Seems the smaller motors are better with the intermediate circuit because their airflow isn't great enough at low to mid rpm to pull enough fuel from the boosters.
Big cids, like yours, don't really have this problem.
I'm no carb guru, thus why I would talk to AED. They have built many succesful carburetors.
07-13-2015, 06:32 PM
#15
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Nothing wrong with a 3 circuit on a big motor. They work great. AED does a lot of Marine carbs. There are a ton of them running around down here. If you don't feel comfortable diving into these carbs I would send them back. But b4 you do that what is the compression, fuel being used and it would be really nice to know what plugs are in the motors. It doesn't take much to foul a plug and once fouled good luck trying to make it idle.
07-13-2015, 10:00 PM
#20
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This is a scenerio where an o2 sensor can be an invaluable tool.
Is it really rich on the idle circuit, or is it the intermediate circuit thats rich, or is it really lean at idle, and rich in the intermediate circuit, etc.
My guess, is its too lean on the idle circuit. Backing the mixture screws out, and you just cant get enough fuel. Putting in a smaller idle air bleed, will reduce the amount of air added to the idle "mixture", helping it have a richer mixture so to speak, but may not add enough raw fuel. The only way to add more fuel, is by enlarging the idle jet (Idle feed restrictor). I think alot of guys look at air bleeds as a mixture tuning device, but they are more for tuning the timing of the carb's circuits, rather than adjust the mixture of the carb. The amount of fuel added to the mix, has to pass thru the idle jet before air is introduced from the air bleed. Then the air/fuel mix, is regulated by the mixture screw setting. To get more fuel, idle jet needs to go bigger. .
Being a 3 circuit, that throws a whole nother circuit into the mix, to be tuned. Without an 02 sensor, you're gonna have to do lots of experimenting. Where I would go, is setting the throttle blades back to the proper transition slot exposure, and then slightly larger on the Idle jet, and get some more fuel flowing at idle to the engine. That is, if they are screw in style, not sure what AED uses. Get it to stop stalling while shifting around the dock, then play with air bleeds, tuning of the intermediate circuit, main circuit, etc.
I've rarely seen bigger power marine engines stall when shifting, from being to rich. Almost every time it was from too lean. I've even seen carbs dripping raw fuel from the boosters that were messed up, still run when shifted. Now, if its idling in gear and starts stalling while idling out of the channel from flooding, thats different. I've also seen 3 circuit dominators get so rich off idle that they flood the engine with gas, making it a blubbering pos getting on plane.
Full Force Tim bolted on a pair of 1050 quickfuels on his engines, and they idle, shift, and do everything just fine out of the box. Tuning main circuit is easy on boats. Trying to fix what you have going on, can be a time consuming pain in the azz, and it really shouldnt be. Its not like you have some wild, high compression, monster cammed , 8500RPM engine setup. I watched my friend CONSTANTLY tuning on his 3 circuit dominators that were custom built for him, on some 700HP 540's. I've seen 1200+HP engines that were less finicky than his setup. Irregardless, you prob paid good money for these carbs. I'd be calling AED and see what they suggest.
Is it really rich on the idle circuit, or is it the intermediate circuit thats rich, or is it really lean at idle, and rich in the intermediate circuit, etc.
My guess, is its too lean on the idle circuit. Backing the mixture screws out, and you just cant get enough fuel. Putting in a smaller idle air bleed, will reduce the amount of air added to the idle "mixture", helping it have a richer mixture so to speak, but may not add enough raw fuel. The only way to add more fuel, is by enlarging the idle jet (Idle feed restrictor). I think alot of guys look at air bleeds as a mixture tuning device, but they are more for tuning the timing of the carb's circuits, rather than adjust the mixture of the carb. The amount of fuel added to the mix, has to pass thru the idle jet before air is introduced from the air bleed. Then the air/fuel mix, is regulated by the mixture screw setting. To get more fuel, idle jet needs to go bigger. .
Being a 3 circuit, that throws a whole nother circuit into the mix, to be tuned. Without an 02 sensor, you're gonna have to do lots of experimenting. Where I would go, is setting the throttle blades back to the proper transition slot exposure, and then slightly larger on the Idle jet, and get some more fuel flowing at idle to the engine. That is, if they are screw in style, not sure what AED uses. Get it to stop stalling while shifting around the dock, then play with air bleeds, tuning of the intermediate circuit, main circuit, etc.
I've rarely seen bigger power marine engines stall when shifting, from being to rich. Almost every time it was from too lean. I've even seen carbs dripping raw fuel from the boosters that were messed up, still run when shifted. Now, if its idling in gear and starts stalling while idling out of the channel from flooding, thats different. I've also seen 3 circuit dominators get so rich off idle that they flood the engine with gas, making it a blubbering pos getting on plane.
Full Force Tim bolted on a pair of 1050 quickfuels on his engines, and they idle, shift, and do everything just fine out of the box. Tuning main circuit is easy on boats. Trying to fix what you have going on, can be a time consuming pain in the azz, and it really shouldnt be. Its not like you have some wild, high compression, monster cammed , 8500RPM engine setup. I watched my friend CONSTANTLY tuning on his 3 circuit dominators that were custom built for him, on some 700HP 540's. I've seen 1200+HP engines that were less finicky than his setup. Irregardless, you prob paid good money for these carbs. I'd be calling AED and see what they suggest.
