Login    Forum    Search    FAQ

Board index » Racing Forum » Fuel Systems




Post new topic Reply to topic  [ 44 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 8:17 am 
Offline

Joined: Sun Nov 11, 2007 10:33 am
Posts: 1293
Location: Montgomery, Alabama
Quote:
So if the 3rd circuit is useful at the gear change, and the term "fall back" comes to mind here, then it would likely benefit the stick shift guys more as there's more gear changes per run?


IMO there isn't a bigger "Tug" on an engine then a 1-2 gear change on a glide. I have never ever seen a lean spike in my o2 logs at this point. In fact if you removed RPM from the graph you wouldn't know where the shift was.


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 10:44 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 4:11 pm
Posts: 2749
Location: Shepherdsville, KY
Ken0069 wrote:
So if the 3rd circuit is useful at the gear change, and the term "fall back" comes to mind here, then it would likely benefit the stick shift guys more as there's more gear changes per run? :-k


There's less than 1,400 RPM drop on any of my gear changes so I would think there's less fall back change than with a glide but again I guess that depends on how loose your convertor is. I always felt that one of the advantages to using a stick was you could keep the engine in it's peak power band.

_________________
Chuck Woloch

Chuck's Automotive
Full line Computech dealer
chucksautomotive@yahoo.com
Image


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 12:30 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
My dragster, with a 1:69 planetary only drops 500 RPM at the gear change? O:)

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 12:59 pm 
Offline

Joined: Sun Nov 11, 2007 10:33 am
Posts: 1293
Location: Montgomery, Alabama
Ken0069 wrote:
My dragster, with a 1:69 planetary only drops 500 RPM at the gear change? O:)


Sounds like your shifting 500 to 700 over flash rpm.

I shift at 7800 and fall back to 6900 and the flash is 6750.


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 2:34 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
If you setup and tune a 2 circuit properly you wont get a lean spike. Its why we use them. If you run a 2 circuit with a oversize main jet and use too many emulsion bleeds and an oversize HSAB to lean it back again at the top end your going to have a large problem with fuel flowing into and out of the air well and fluctuating the mixture issuing from the booster. Adapting the design to have a 3rd circuit is not the way to fix a tuning fault with a 2 circuit. Whatever the problem may have been back in the day when the 3 circuit was made could have been fixed with a 2 circuit. But it probably required a more expensive research and retooling process. From what I've seen most of the problem with pulsing air flow comes from the T-slot. The t-slot reacts to pulsing waves at much lower intensity than what will affect the booster. The engine is the thing that needs to be fixed firstly. Not even EFI likes pulsing flow, the systems take too long to respond.


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 3:01 pm 
Offline

Joined: Sun Nov 11, 2007 10:33 am
Posts: 1293
Location: Montgomery, Alabama
Can I get an AMEN!! \:D/ \:D/ \:D/


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 9:29 pm 
Offline

Joined: Thu Jan 29, 2009 10:59 am
Posts: 438
Location: Auburndale, Florida
As the T-slot was mentioned I'd like to note that I typically run my T-slot jets in the high .050s. The my 3 circuit is calibrated that way.

shrinker, thanks for pointing out the simplicity of the intermediate circuit itself. Not much there if one thinks about it. Just a controlled dribble as you said.

I'm running the intermidiate quite lean now. It's probably why it runs so well in the water and doesn't load up like some.


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Fri Dec 30, 2011 11:36 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
And speaking of 3rd circuits? Did you ever see this Bruce? I think I did this before you joined here. Look about half way down the page. ;-)

viewtopic.php?f=6&t=1840&p=18868#p18868

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Sat Dec 31, 2011 12:38 am 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
How did that finish up Ken?


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Sat Dec 31, 2011 10:37 am 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
shrinker wrote:
How did that finish up Ken?


Well, it's documented in one of the threads on here but overall it did make it rich enough that it developed some consistency. Still can't tune it with jet as it's got .210s in it now and the cross wells are .206 and the stake tubes are .213. If memory serves I started out with a .040 bleed in that circuit and wound up with something around .050s. One thing that did change though in the main circuit was that I went from MABs in the upper teens/low 20s to one around .030/.033 if memory serves and pretty much have the AFR flat line. It is a little phat in the water box but it's nothing that I can't live with. But get this, it did phatten up the corners to a point that I had to grind some of the flare off the banjos in that area.

I went through that whole evolution thingie of balancing EGTs with zip ties and at one point I had'em all within 80* or so but I don't remember there being any difference in performance. And along that line, I was talking to Kowalsky back a week or so ago and he had the exact same experience with a comp engine on his dyno earlier this year, ie, balanced EGTs and AFRs on all cylinders but there was no difference in either power or torque when he finished?

Donee has the other pair of plates I made and he's going to put them in a 1050 he has. His 565 might work better than my SBC as it might generate more signal at the boosters. He also got a pair of those methanol metering blocks from Holley like the ones that are in my carb. Hopefully we'll get to see how his does next year.

All this came from discussions that I had with Maley back when we first started talking on the phone and I believe that he did a methanol Dominator that same way out there in Oregon after we found out that mine worked reasonably well.

Ennywho, I'm planning to switch back to a single carb some time this coming summer and I'll have two 1150 methanol carbs to test with, ie, this one and the second one I did with some major mods to the metering blocks and banjos. Have to make a scoop tray for the single Dominator and this time around I “might” just try to setup the linkage to run one sideways. ;-) Won't THAT be a hoot at the track! =;

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Sun Sep 30, 2012 8:30 am 
Offline

Joined: Thu Jan 29, 2009 10:59 am
Posts: 438
Location: Auburndale, Florida
Been a long time since this thread has been visited. Since then I've run my 3 circuit carb for all this time. It's been doing well and it runs the same times consistantly.

I'd like to share the configuration.

Holley HP
1.78 venturi
2.125 throttle
BLP wide body blocks, gas
IJ .040, not lowered yet
IAB .059
IntInletJet .035
IntOutletJet .050
IntAB .073
MJ .120 BLP
MAB .031
4 x .082 make up air holes in blades
Boosters are .500 ID 12 hole BLP billet parts

Last pass was 5.838@119.21 with 310 passes on the engine


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Sun Sep 30, 2012 3:29 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
OK Bruce, I've got to ask. Here you say you're running now and have been running a 3 circuit carb all year?? So why does your signature state that you're running a "junky 2 circuit"?? :-k ;-)


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Sun Sep 30, 2012 4:12 pm 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
Trader :-#

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: 3 Circuit Dominators
 Post Posted: Sun Sep 30, 2012 8:34 pm 
Offline

Joined: Thu Jan 29, 2009 10:59 am
Posts: 438
Location: Auburndale, Florida
Ken0069 wrote:
OK Bruce, I've got to ask. Here you say you're running now and have been running a 3 circuit carb all year?? So why does your signature state that you're running a "junky 2 circuit"?? :-k ;-)


Because I'm still in test mode and I wanted to make sure the test was thorough. =;

I'm still not convinced 3 circuit is the way though. I think I've got the calibration right. However, after it's all said and done the added complexity of an intermediate is probably not worth the effort. Without the BLP wide blocks I would not have even tried.


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 44 posts ]  Go to page Previous  1, 2, 3

Board index » Racing Forum » Fuel Systems


Who is online

Users browsing this forum: No registered users and 3 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: