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 Post subject: Demon tuning
 Post Posted: Sun Jul 15, 2012 4:25 pm 
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Hi Guys;
Seems there’s some carb tuners here, maybe someone would give me some advice on my tuning efforts.
540 BBC, 6-71 Blower, 10 Lbs boost, 8.4 CR, 254 /264 @050, .715, .715, 114deg. Burning AVGas
2 x 850 Mighty Demons
Factory calibration: Currently:
IAB: .070 .070
HSAB: .031 .028
E-holes:.031 .031
Plug plug
.031 .031
Plug plug
.031 .031
PVCR: .059 .076
Tsr open .063
IFR .038 (top) .033 (bottom)
MJet 85 89
SJet 93 97
PV 4.5
Tuning with an Innovate LM-2, @ 1700 ft. elevation , AFR’s low ~ mid 12’s, all thru the 1/4mile running great, plugs are a nice tan colour, quite happy with it other than: I’d like to try it a bit richer, maybe mid ~ high elevens, low 12’s. Next race for me is @ sea level. Not sure if I should go up more on jetting (already up 4 sizes from factory) or down on HSAB.
Any / all comments welcome and Thanks in advance. =;
Howard


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 Post subject: Re: Demon tuning
 Post Posted: Sun Jul 15, 2012 4:31 pm 
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Oh, I see the formatting changed when I posted, tried to edit but still ran them together.
The second set of numbers are what's in them currently.
Sorry bout that.


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 Post subject: Re: Demon tuning
 Post Posted: Sun Jul 15, 2012 5:45 pm 
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Well, that turned into a mess, it re-formats and runs together when I post, try this;
Hi Guys;
Seems there’s some carb tuners here, maybe someone would give me some advice on my tuning efforts.
540 BBC, 6-71 Blower, 10 Lbs boost, 8.4 CR, 254 /264 @050, .715, .715, 114deg. Burning AVGas
2 x 850 Mighty Demons
Factory calibration: ---------- Currently:
IAB: .070 --------------------- .070
HSAB: .031 ------------------- .028
E-holes:
.031---------------------------.031
plug ---------------------------plug
.031---------------------------.031
Plug---------------------------plug
.031---------------------------.031
PVCR: .059 ------------------.076
Tsr open ---------------------.063
IFR .038 (top) ---------------.033 (bottom)
MJet 85 -----------------------89
SJet 93 -----------------------97
PV 4.5
Tuning with an Innovate LM-2, @ 1700 ft. elevation , AFR’s low ~ mid 12’s, all thru the 1/4mile running great, plugs are a nice tan colour, quite happy with it other than: I’d like to try it a bit richer, maybe mid ~ high elevens, low 12’s. Next race for me is @ sea level. Not sure if I should go up more on jetting (already up 4 sizes from factory) or down on HSAB.
Any / all comments welcome and Thanks in advance.
Howard


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 Post subject: Re: Demon tuning
 Post Posted: Sun Jul 15, 2012 7:36 pm 
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Joined: Tue Apr 18, 2006 3:20 pm
Posts: 1457
Location: Missouri
Howard,
You might try using the "code" function when posting data that you want to format a certain way. It helps to layout the data. I also use the preview before submitting.

It is right next to the "quote" button when you are writing a reply or new post.

Rick
Code:
Here is data inside the "code" function

 A               B                C
100             200              300
101             201              301


And here is the same exact data w/o the code function
A B C
100 200 300
101 201 301


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 Post subject: Re: Demon tuning
 Post Posted: Sun Jul 15, 2012 7:51 pm 
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Wow, thanks Rick cuz you just showed me something I didn't know. That will come in handy for sure. \:D/


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 Post subject: Re: Demon tuning
 Post Posted: Sun Jul 15, 2012 10:05 pm 
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Posts: 26
Thanks Rick;
I had laid it out in Word, thinking it would retain the formatting but no cigar.
Learn something everyday [-(
Howard


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 Post subject: Re: Demon tuning
 Post Posted: Sun Jul 15, 2012 10:38 pm 
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Howard are these carbs out of the box or were they modified by someone?? :-k

And what are they doing, or not doing that you'd like to change?

jmarkaudio and Nomad have done some stuff with Demon carbs so maybe they can offer some advice. I see you've gotten the nomenclature down so that's a good first step. ;-)

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 Post subject: Re: Demon tuning
 Post Posted: Mon Jul 16, 2012 10:30 am 
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I bought these carbs used. I don't think they've been modified in any way by anyone other than myself. One was a "blower carb" from BG, the other N/A. On the "N/A carb" I knocked out the P/V blowout protection, plugged it and "boost referenced" the P/V the same way the other one was.
I read a few threads on "Demon tuning" on the old Innovate site and made a few changes that were suggested in there. These are my "current" calibration. I'm quite happy with the way it runs, idles great, I can launch it from a 1000 rpm idle, mash the throttle and it just leaps off the line with no stumble. AFR's are roughly low ~ mid 12's all thru a run, no "lean out" on the top end.
I'd just like to try getting them a bit richer but I'm already up 4 jet sizes from "factory calibration" and my question is: should I go up more on jetting or down on HSAB or something else ?
From the factory jetting, I went up 2 jet sizes, then 2 more, MPH picked up both times.
Timing is locked @ 30. Burning AVGas 100 LL (Low lead).

Code:
                       Factory Calibration                            Current calibration
IAB                                     .070                                                  .070
HSAB                                   .031                                                  .028
E-Holes                                .031                                                  .031
                                         plug                                                  plug
                                         .031                                                  .031
                                          plug                                                  plug
                                          .031                                                  .031
PVCR                                   .059                                                  .076
TSR                                     open                                                  .063
IFR                                     .038  Top                                           .033 Bottom
Mjet                                      85                                                     89
SJet                                      93                                                     97
PV 4.5


I've made 8 "Test & Tune" runs at a "Desert" track ~ 1700 ft elevation, next race is at sea level (Mission BC ~ normally really good air).
I'd like to try a bit more ign advance but kinda wanted it a bit richer before I go there.
more Jet ?
Less HSAB?


Last edited by cuslog on Mon Jul 16, 2012 10:38 am, edited 1 time in total.

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 Post subject: Re: Demon tuning
 Post Posted: Mon Jul 16, 2012 10:34 am 
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Posts: 26
Hmmmmmmm, even using the "code function" it's still a bit funky (looked good in the preview too).
Hope you can make sense of it.
Thanks,
Howard


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 Post subject: Re: Demon tuning
 Post Posted: Mon Jul 16, 2012 11:14 am 
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Plug the bottom .031 e-bleeds and replace the top two .031's with .026's, and .026 in the main air bleeds.


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 Post subject: Re: Demon tuning
 Post Posted: Mon Jul 16, 2012 11:47 am 
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Thanks Mark;
I thought there may be a bit more to it than just throwing more jet at it, just didn't know what it would be.

Howard


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 Post subject: Re: Demon tuning
 Post Posted: Wed Jul 18, 2012 9:56 am 
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Joined: Wed Jul 11, 2012 11:06 am
Posts: 26
Soooooo;
these e-holes are at the bottom of a "counterbore".
I'm wondering; is it OK to just tap the counterbore and "stack" a brass set screw in there on top of the original .031 ? OR should the counterbore be drilled deeper so the new set screw W/ smaller hole is at roughly the same depth in the counterbore as the original ?
Thanks,
Howard


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 Post subject: Re: Demon tuning
 Post Posted: Wed Jul 18, 2012 10:52 am 
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I use fishing line lead split shot and a piece of coat hanger to tamp it down in the holes you are NOT going to use. it's also relatively easy to remove if you want to open it back up. ;-)

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

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 Post subject: Re: Demon tuning
 Post Posted: Wed Jul 18, 2012 2:14 pm 
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I open them up to around .070 to leave a step for the set screw to seat against, not go all the way thru. Tap it for 6-32 and hit up McMaster Carr for set screws.


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 Post subject: Re: Demon tuning
 Post Posted: Wed Jul 18, 2012 3:13 pm 
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Posts: 26
Ken;
The ones I indicated as "plugged", simply aren't drilled, I hadn't looked at them in awhile.
Thanks anyway.

Mark;
Thanks, good idea, that'll let my tap go a bit deeper, the 6-32 x 3/16 that I have were a bit above "flush" with the channel.
McMaster-Carr refused to ship to Canada, wouldn't even ship to my broker in Washington State :-
I got them another way.


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