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Question for Holley Dominator gurus
#928395
02/14/11 12:17 AM
02/14/11 12:17 AM
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Joined: Jun 2004
Posts: 59
Sacramento, Ca
sanger440
OP
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OP
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Joined: Jun 2004
Posts: 59
Sacramento, Ca
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I crew chief for my buddy in his 65 chevelle running superpro a couple of times a month. 3200 pounds , 496 BBC, edelrock heads, 1050 3 circuit holley dominator(done by Promax 1.5 years ago) . We run 10 inch tires (car is not tubbed). We leave on the throttle stop at 4100 rpm, come off the throttle stop after 1.5 seconds and run 10.90 et's. We leave easy on the throttle stop to control tire spin with small tires. Car runs very consisitent and has finished top 5 the last 2 years in super pro.
But the car will cut out first pass of the day almost each race. If we put new plugs (or clean plugs) in it does not cut out. In an effort to figure out [Edited by Moparts - Family Friendly Site - Keep it clean] is going on I put a Wide Band O2 sensor and datalogged the runs today.
A/F ratio averaged 12.7-12.8 after the 60 foot mark when the car was off the throttle stop. So the car runs good when at full throttle off the TS.
But in the water box doing the burnout, the A/F averaged 10.2-10.3, staged on the throttle stop at 4100 rpm, A/F was about 11.2-11.4. The A/F for the first 60 feet or so (still on the TS) stayed about 11.5.
So I figure the car is cutting out first pass of the day because it is too rich and the motor does not have much heat in it. Once the car has one pass and is cleaned out, it no longer cuts out.
So here is the question: What can be changed on the 3 circuit dommy to lean it out for the burn out, staging on the throttle stop, and running on the throttle stop for the first 1.5 seconds.?
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Re: Question for Holley Dominator gurus
[Re: sanger440]
#928398
02/14/11 02:56 AM
02/14/11 02:56 AM
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Joined: Jan 2003
Posts: 19,361
Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,361
Las Vegas
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If it is only having an issue when cold, first pass then is fine the rest of the day why do you think it is a carb issue? Maybe the car needs ot be warmed up more beofre the first run of the day? Having said that I would do as suggested and play with the idle and intermediate bleeds. It is pretty common knowledge that dominators are pig fat at idle and most are on the intrermediates as well. Being on the stop is not gonna help any. I would look hard at go up on the bleeds a bit on both. If you are going to leave on the stop you need to make it happier down low, IMO. We played with mine a bit to get it happy on the stop. I am on it for a good amount of time and took some tweaking to get it happy there. Then again if it is only happeneing on the first "cold" pass maybe it just is not getting warmed up enough. Just my  Having said all that Warren does pretty good as a racer so it cant be that bad 
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Question for Holley Dominator gurus
[Re: sanger440]
#928401
02/14/11 01:49 PM
02/14/11 01:49 PM
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Joined: Apr 2006
Posts: 3,675
Akron, Ohio U.S.A.
roadhazard
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master
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Akron, Ohio U.S.A.
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I'm no expert by any means but you have a wide band so warm it up and see what the A/F is at idle. That will let you know if that needs adjustment. I'd set this first. Then adjust the intermediate circuit until the A/F is in line and or the motor runs like it should. JMO 
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Re: Question for Holley Dominator gurus
[Re: roadhazard]
#928402
02/14/11 02:58 PM
02/14/11 02:58 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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If the car won't run when it's cool, you need to fix the carb. Your numbers show that it is rich at low speed, so work on this.............but......180 degrees is NOT cool, so I would check a couple other things. If it stumbles, unless you put fresh plugs in, thats an ignition issue. You might try a range hotter plug, to help clean the plug better. I never saw ignition system posted, but you may need to close the gap up on the plugs, to make it easier to light the charge........but you still need to clean the carb up at low speed.
Monte
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Re: Question for Holley Dominator gurus
[Re: Monte_Smith]
#928405
02/14/11 11:46 PM
02/14/11 11:46 PM
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Joined: Jan 2003
Posts: 19,361
Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,361
Las Vegas
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Agree with what has been posted already. What plugs do you run now? As stated Dominators are notoriously fat on the idle circuit. Easy to fix with a bleed change. Gonna assume the throttle blades are not open to far allowing for to much transgfer slot to be exposed, cuase that will make it pig fat.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Question for Holley Dominator gurus
[Re: Al_Alguire]
#928406
02/15/11 01:46 AM
02/15/11 01:46 AM
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Joined: Jun 2004
Posts: 59
Sacramento, Ca
sanger440
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Joined: Jun 2004
Posts: 59
Sacramento, Ca
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I will have to check exacty what plugs we run, autolite brand but not not sure what heat range. Something off the shelf at Kragen probably.
The ignintion is a MSD6a, we have tried the back up box and a switched to a new coil last season, car still cuts out first pass. I have ohmed the MSD plug wires, they were within spec, and new cap and rotor have been installed. We run a high output alternator, and have verified the MSD sees 14 volts when the car is running. Distributor is locked out at 35 degrees and still never kicks back. So I am thinking it is not the ignition.
The car starts excellent hot or cold, it idles good, never stumbles or surges when staging or idling around the pits. Never kicks back when starting, never seems to flood or act like it is too loaded up. But it will cut out in the water box first burnout of the day.
So I should try a bigger mid speed air bleed? (I always get this backwards)
It was suggested to remove the air bleed all together? (I don't think he meant to plug it)?
Thanks again for all the suggestions.
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Re: Question for Holley Dominator gurus
[Re: sanger440]
#928407
02/15/11 02:19 AM
02/15/11 02:19 AM
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Joined: Jan 2003
Posts: 19,361
Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,361
Las Vegas
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The higher the bleed size/number the leaner the given circuit will be.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Question for Holley Dominator gurus
[Re: cudadon]
#928409
02/15/11 02:38 PM
02/15/11 02:38 PM
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Joined: Jun 2004
Posts: 59
Sacramento, Ca
sanger440
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Sacramento, Ca
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Quote:
My 02 is always richer in burnout. I believe its from the acc. pump when I hit it to get em spinning, or if you feather it while spinning, the nozzles are squirting right?
Possibly smaller squirters and hotter plugs.
Don
Excellent point Don. I have the data logger set to start logging at 3500 rpm, so it starts when the car is in the burnout. The A/F is in the 10.1-10.3 range while the car is the water box. So the Carb is at part throttle (squirters do work) and is being feathered to keep the rpm about 6000 rpm or so. Once the car is staged, on the trans brake, throttle blades are wide open (so accel pumps are done), and the throttle stop (plate type under the carb) is holding the rpm at about 4100 on the T-brake. The A/F is a little leaner here, but still very rich. So I am hoping the mid speed bleed with help here and down track until TS opens up.
What is your A/F ratio when you are doing your burnout Don?
Charlie.
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Re: Question for Holley Dominator gurus
[Re: sanger440]
#928411
02/16/11 12:16 PM
02/16/11 12:16 PM
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Joined: Nov 2003
Posts: 2,131
New Lenox IL
cudadon
top fuel
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top fuel
Joined: Nov 2003
Posts: 2,131
New Lenox IL
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Quote:
Quote:
My 02 is always richer in burnout. I believe its from the acc. pump when I hit it to get em spinning, or if you feather it while spinning, the nozzles are squirting right?
Possibly smaller squirters and hotter plugs.
Don
Excellent point Don. I have the data logger set to start logging at 3500 rpm, so it starts when the car is in the burnout. The A/F is in the 10.1-10.3 range while the car is the water box. So the Carb is at part throttle (squirters do work) and is being feathered to keep the rpm about 6000 rpm or so. Once the car is staged, on the trans brake, throttle blades are wide open (so accel pumps are done), and the throttle stop (plate type under the carb) is holding the rpm at about 4100 on the T-brake. The A/F is a little leaner here, but still very rich. So I am hoping the mid speed bleed with help here and down track until TS opens up.
What is your A/F ratio when you are doing your burnout Don?
Charlie.
Charlie
My AFR with LM2 in the burnout is 10.3 avg.
It's about the same as yours.
I have seen in the past when I needed to richen the down track run, the burnout was plenty rich!
This why I think it's the acc. pump richening the burnout, I know I use the pedal to keep rpm where I want it.
I use a 2 step so I don't pay attention to AFR on the tbrake, the miss will lie to me.
I don't have a miss or anything when I let go of the button. Don
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Re: Question for Holley Dominator gurus
[Re: sanger440]
#928412
02/16/11 04:03 PM
02/16/11 04:03 PM
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Joined: Aug 2003
Posts: 43,127
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,127
Bend,OR USA
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turn the idle mixture screws in on all four corners to 1/4 to 1/2 turn out from all the way in and look at your AFR  I have had to do that on several Dominators and other carbs. to get them to idle clean and drive clean at low RPM  As already said a hotter plug and bigger idle and intermediate bleeds will help also, change one thing at at time until the motor is happy sometimes you have to change the main jest also
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Question for Holley Dominator gurus
[Re: Cab_Burge]
#928413
09/09/11 09:34 PM
09/09/11 09:34 PM
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Joined: Jun 2004
Posts: 59
Sacramento, Ca
sanger440
OP
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OP
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Posts: 59
Sacramento, Ca
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Well I thought I would reply back now that I know the car is definitely cured of it's morning cut out ritual. What we did was put a power valve in the thing and went down 10 jet sizes. Car never cut out again. We used the same plugs the rest of the year. 02 meter shows about 11.5 AFR in the burnout and when on the TS. Then the rest of the run AFR holds about 12.5 AFR. My buddy ended up winning a Wally in super street at the NHRA Pacific Open in May at Sac raceway. Finally got his car in National Dragster LOL!. He ran back to back 10.900 in the semi and final. It is nice to finally have the car run good all the time. Charlie 
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Engine temp affects A/f ratio More than you might think , i had a mid range that was 11.5 @180 deg , put in a 195 temp t-stat .
