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 Post Posted: Thu May 03, 2012 8:27 pm 
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Ken that's how it was with the.078 mab but the screws were out over 2 turns. I will wait for jmark to see what my next move should be.


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 Post Posted: Fri May 04, 2012 9:26 am 
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OK guys, sorry but I had a major poo bar this morning and had to restore the database from an older copy, therefore there will be some recent posts missing. [-(

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 Post Posted: Fri May 04, 2012 9:52 am 
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driftbuster wrote:
Yes i moved the .040 ij down. I put in the .067 iab and on a cold start it idled low but on its own till it warmed up and the idle came up. Seemed most responsive at 1 3/4 out on the screws. I pulled the carb to check the tslot and the throttle blade is even with the t slot but not exposing any. The timing is locked at 38, i pulled a plug and it was black after idleing. I also blocked the iab at 2000 rpm and got a slight drop in idle.


If you plugs were black prior to getting the calibration close you need to clean them or put fresh ones in. It is near impossible for the engine to clean them once they are black and the engine will not run well until you have clean ones in (white porcelain) as black on the porcelain changes the heat dissipation of the plug, makes them act colder. You will have a tough time making it run well until you do.


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 Post Posted: Fri May 04, 2012 1:14 pm 
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I will put some new plugs in .


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 Post Posted: Fri May 04, 2012 11:25 pm 
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The initial timing has a lot to do with idle quality and idle speed. If you lock your timing at total advance you are usually increasing your idle speed RPM quite a bit. Try lowering your initial timing to around 20 degrees and see if that doesn't bring your idle back into line ( you can do this temporarily by locking the timing at 20 degrees and adjusting the carb to see how it acts). There's a reason OEM cars have a timing curve. Also you can usually get away with a lot less t-slot exposure on the secondaries (close to .000 t-slot showing) to get the primaries where they need to be, which is close to square. It's all a balancing act that takes time and tinkering. I wouldn't extend your t-slots until you have tried everything else.

As a starting point I would set the timing to 20 degrees, close the secondaries till the t-slot was just showing, (a couple of thousands, to keep the circuit wet), open the primaries till the t-slot was showing about .020. Fire it up and see where it idles, if it's too high back the timing down or close the primaries a little. If it idles too low open the secondaries a little or give it a little more timing, fine tune it with the idle jet and idle air bleed.

Good luck,
Keep us posted,

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 Post Posted: Sun May 06, 2012 9:57 am 
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I really appreciate the help guys, im used to motorcycle, and snowmobile carbs with only a couple of available tuning options and i have alot more adjustments to balance with the dominator. It will take me some trial and error to get this thing right but i'm ready to learn. Unfortunately i can't work on it this weekend but i will update shortly.
Thanks for all the help.


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 Post Posted: Thu May 10, 2012 5:59 pm 
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Ok guys the update is not good yet, i did back the timing down to 20 and the results were that i was able to get it to idle around 1200 with .020 primary t slot and the rear right oon the edge of the slot. Other than gaining some t slot everything was the same. I installed new plugs, ngk ur 4 and the porcelain started to turn black after a five minutes ideling and this really has me scratching my head. I have the carb set to specs, could it be someting else? The plugs and eye burning tells me it's rich but if i lean it out the responce suffers and richening the iab helped bring the screws in some which is confusing. On cold start i need to keep it running till it warms up a bit, covering the iab cold didn't change much and covering them warm results in a slight rpm drop @ 2000 rpm.

The car runs good, but whats up with the plugs and eye burning from the exhaust?


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 Post Posted: Thu May 10, 2012 7:26 pm 
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How much Tslot with the blade 100% shut?


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 Post Posted: Thu May 10, 2012 7:33 pm 
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You said if you screw the mixture screws in just a little it wants to die, have you tried giving it more fuel to see how it acts, if you are trying to run it too lean it will really stink bad and make your eyes water. Without being there it's hard to know what's really going on.

If it's not running lean, I would try to get it to idle without blackening the plugs first. So idle it down without regard to the t-slots, I would try to keep the primaries and secondaries even. So start at around 2 turns open on both, then open or close both the same amount to control the idle. I don't know how much duration you're running, but you should be able to idle at 800 to 1000 easily. Adjust the idle mixture screws, IJ and IAB until it will idle without running so rich. If you can get it to idle right, then you can work on the height of the t-slots.

You may also have fuel leaking into the manifold from the PVC area or the accelerator pump circuit, or you could have a vacuum leak. Lot's of different things could cause the symptoms you're having.

If you could get an O2 sensor it would help you to see what's going on.

Just my thoughts, you'll get a handle on it,

Good Luck!

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 Post Posted: Thu May 10, 2012 8:01 pm 
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Scott Smith wrote:
How much Tslot with the blade 100% shut?

If i back the idle screws off to close the blades no slot is exposed.


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 Post Posted: Thu May 10, 2012 8:15 pm 
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Good,,,,,,,,,,Now what I did was turn the speed screws till you get the slot almost square and then mark the speed screw to the part that it threads into. Now do the same thing to the secondary's . Now when you need to turn the speed screws you can turn them the same amount and keep the slot the same on the primary's and secondary's. If you need to turn them to increase the idle remember or write down how much you turned them...1/4 or 1/2 turn...Remember you need to turn them both the same amount..
As you get closer to the right mixture you should be able to close the blades some to get them back to a square slot...

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 Post Posted: Thu May 10, 2012 8:27 pm 
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Duration is 252 intake, 260 ex. I can get it idle under 1000, drops 200 when i put it in gear.

I did richen the iab bye going down to .067 suggested bye jmark and it helped bring in the corner screws some. I then tried a .035 ij and it was lean, also tried a .081iab that also seemed lean as both really burned eyes. Could being lean also cause the black plugs at idle? If so i think it needs more fuel.
Thanks


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 Post Posted: Thu May 10, 2012 11:40 pm 
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I don't think the plugs will turn black at an idle if it's running lean, at least I haven't seen or heard of it happening.

We need to find out where your t-slot is in relation to the throttle blades when they are totally closed. With the carb off close the blades completely, scribe a mark from the manifold side of the blades in the t-slot area, then open the blades and measure from the scribe mark to the bottom of the t-slots and let us know what the measurements are. The t-slots should come down to the scribe mark.

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 Post Posted: Fri May 11, 2012 8:07 am 
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And hold the carb up in front of a light and make sure the blades are seated correctly in the bore.
Sometimes you have to loosen them up from the throttle shaft and let them fall or lightly tap them in the correct position and re tighten the screws.


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 Post Posted: Fri May 11, 2012 8:08 am 
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BTW,
It sounds to me like it's getting too much air and your limiting the RPM with fuel. Does the RPM go up when you turn the screws in?


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