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Boat Nut
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Discussion Starter #1
I have twin dominators, with a Victor Ram on my 540

I find it like lots of fuel to lite off, throttle is snappy and all, but little difficulty in starting, and black smoke out the right header, on the hit. I have soft progresive cams in for the secondaries. I'm thinking I may need to switch to progressive cams?? This will get fuel to the left cylinder banks on start-up, and reduce the smoke on the right side. Am I sorting this out right?
 

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I would look at fuel leaks in the carb. Could be boiling over after shut down or just leak fuel from a float level problem. If it is flooding like that keep a eye on the oil. I don't know. :)sphss
 

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You can use the spring tension on the accelerator pump arm to make some adjustment. On my doms, I increased the "lash" to reduce the amount of pump shot off Idle. It cleaned it up.This was on a blower set up.
 

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These are exactly the reasons why I despise sideways mounting. Even on a Blower. Besides what you are experiencing, how's the plugs read, bank to bank?

Ray
 

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These are exactly the reasons why I despise sideways mounting. Even on a Blower. Besides what you are experiencing, how's the plugs read, bank to bank?

Ray
Really! Amazing the number of people running Doms on a blower and don't experience any problems. So when running 4150s on a tunnel ram inline, at part throttle, using you theory, shouldn't the cylinders 1, 2, 5 and 6 run differently than 3, 4, 7, and 8?



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I have thought about this too and have come to the following conclusion...

Orientation of the carburetors doesn't matter because the only way for the air and fuel to get into the plenum is through the opened butterfly... no matter where it is.
 

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I have twin dominators, with a Victor Ram on my 540

I find it like lots of fuel to lite off, throttle is snappy and all, but little difficulty in starting, and black smoke out the right header, on the hit. I have soft progresive cams in for the secondaries. I'm thinking I may need to switch to progressive cams?? This will get fuel to the left cylinder banks on start-up, and reduce the smoke on the right side. Am I sorting this out right?
you say "on the hit"? is that full throttle or part throttle? if it's part throttle, what does it do with a full throttle hit from idle? do you have the same size squirter nozzles all the way around? are the accel pumps exactly the same size all the way around, and are they set exactly the same way???
 

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Boat Nut
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Discussion Starter #8
you say "on the hit"? is that full throttle or part throttle? if it's part throttle, what does it do with a full throttle hit from idle? do you have the same size squirter nozzles all the way around? are the accel pumps exactly the same size all the way around, and are they set exactly the same way???
Still in the early stages of dialing these in. No hesitation on the hit, partial or full throttle. The squirters are the same on all sides. Partial throttle yields black smoke, on the right side as does full throttle on the full hit. Im getting too much fuel on the right side, not enough on the left side. On start up it fires right up with a shot of fuel from all the pumps, but hard starts with just the primary shot of fuel. The left side exhaust is totally clean.
 

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Power Valves? Double check you float levels!!!
About the only way to have one side run that much richer is if you have fuel puddling in the manifold.
You say it starts OK with a full shot, but not with a partial shot. But are you leaving the throttle wide open when starting with the full shot, or closing it back to the same place as when you only give it a partial.
Why do you think you not getting enough fuel on the left side. I understand saying too much on the right. But why do you say not enough on the left. Plug readings?

Which side of the engine are the primaries on?

Does it blow black smoke all the time your running it, or only when you start it or hammer it?
What plugs and ignition are you running?



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Still in the early stages of dialing these in. No hesitation on the hit, partial or full throttle. The squirters are the same on all sides. Partial throttle yields black smoke, on the right side as does full throttle on the full hit. Im getting too much fuel on the right side, not enough on the left side. On start up it fires right up with a shot of fuel from all the pumps, but hard starts with just the primary shot of fuel. The left side exhaust is totally clean.
hesitation is usually a leaning condition, so if you're seeing black smoke, wouldn't expect it. do these things have power valves, or are they blocked with the carbs squared? how far open are the mixture screws? have you made any changes to bleeds or ifr's? has this thing always behaved this way or did it just start?
do you have a vacuum leak somewhere? are there vacuum ports on these carbs that have rubber caps? and if there are, are all of them still on? any of them old and cracked, or not tight? is there any kind of port off the carb bases or intake manifold that is leaking at all? any cracks/checks in hoses off the carb/intake?
 

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First question would be how does it run after start and after it cleans out? Second would be how does it run at the ramp when pulling out after the day? Second would be (and most important) do you run the carbs dry before the tow home, When you are towing home and bouncing along the road with full floats and a engine not running ( with feul splashing down the runners and and finding every open valve to load up) . Just a thought. M
 

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For what its worth I set the floats on my TR doms at the bottom of the site plugs then lower them 2 wrench flats below. Any higher than that there will be some drips from the butterfly shafts when it sits after running which means fuel is dripping inside. Consequently it also starts harder when that scenario exists. Good luck!
 

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Boat Nut
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Discussion Starter #13
I'll lower the float levels a bit more.... clearance the booster levers, and go over stuff once more. Once cleared up, it does not smoke from 1/4 to full throttle hits. It for sure needs one full throttle pump from all four pumps to start easy.
 

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Discussion Starter #15
Are you running 1 to 1 on the carbs? If not maybe try that and set it up square.

1 to 1 meaning secondary linkage? I'm using soft progressive at 1/2 throttle secondaries start to open. All jets and squirters are the same on all sides.
 

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I'll lower the float levels a bit more.... clearance the booster levers, and go over stuff once more. Once cleared up, it does not smoke from 1/4 to full throttle hits. It for sure needs one full throttle pump from all four pumps to start easy.
Ive not messed with duel doms much but the single i ran and 2 660's would hot start without touching gas pedal.
If you shut it off..wait 30 seconds does it restart clean with just the key? If you have to use acc. pumps to restart, it shouldn't have been idling in the first place....Acc pump is for accelerate....not part of idle circuit or hot start circuit...

Are you restarting with the throttle open? Cranking with throttle open is clear flood mode and with the amount of fuel a dom squirts it will take some heat in the cylinders to burn all the soot out.

And haven't tried it with doms but my olds with t/r and 2 660's would idle pretty decent on one carb. I disconnected the linkage, closed the throttle with the idle screw....got one carb sorted out...shut it down and did the other one..it was one with the problem and i found it by placing my finger on the center of each booster and the one that didn't cause a change....had a freekin rottweiler hair in it...:)bulb

And someone straighten me out if i was taught wrong but....Accelerator pump 'lash'?

  • Motor needs that squirt the instant the throttle opens at all...if it has 'lash' in the linkage the motor should hesitate...or blow big flame out the carb when it backfires...if it doesn't need it the motor is getting fuel from someplace else....
  • The lash deal? something like 15 thou between the arm and linkage at WOT.
And motor in water always needs more squirt than motor on trailer...
 

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For what its worth I set the floats on my TR doms at the bottom of the site plugs then lower them 2 wrench flats below. Any higher than that there will be some drips from the butterfly shafts when it sits after running which means fuel is dripping inside. Consequently it also starts harder when that scenario exists. Good luck!
If it's dripping just sitting there isn't it dripping when running? If fuel is getting by the needle/seat at normal setting i think just adding more pressure to the sealing surface
is just covering one problem and potentially covering other ones...bad n/s..sunk float, excessive fuel pressure....
just saying/just asking:)hand
 

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If it's dripping just sitting there isn't it dripping when running? If fuel is getting by the needle/seat at normal setting i think just adding more pressure to the sealing surface
is just covering one problem and potentially covering other ones...bad n/s..sunk float, excessive fuel pressure....
just saying/just asking:)hand
Well when it sits for a while there is a heat soak effect that tends to further expand the fuel causing it to drip. Add some rocking from wave action and quite a bit of fuel can spill into the carb. Many factors could be at work in this case including incorrect float level, too much idle transfer slot showing, accelerater pump cam timing and volume, ignition timing and curve, idle screw adjustment etc. My power valves are plugged and the carbs are squared so if he is running power valves there is another thing to look at. I've run several motors with Dominators and in each case a float level set below the sight plug worked best in terms of consistency.

If the n/s are bad lowering the float level will not solve the problem and the same is true with a sunk float. In those cases it will not only run poorly, but so much fuel will be dumping into the carb it would be dangerous.
 

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1 to 1 meaning secondary linkage? I'm using soft progressive at 1/2 throttle secondaries start to open. All jets and squirters are the same on all sides.
Well thier you go. When you pump it your shooting the one side first and probly more than the other side because Im sure your not flat footing the pump action. So your flooding the one side.

Id set it up 1 to 1 and run 30cc pumps front and rear and play with pump cams if needed. Sounds like your jetting is okay from how you say it runs.
Well it sounds good from here anyways.:D
 

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Before you try the other suggestions, try mine. Not much is involved. Make some slop in the primary squirt. One Big pump to the floor and wait 5-7 seconds. It should fire right off. And Tune the Idle as you know how. Watch your plugs and Giver hell. I know you are aware of this already. DEL.
 
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