Re: Stumble from my 850 Mighty Demon?
[Re: dduster73]
#69348
06/07/08 07:49 PM
06/07/08 07:49 PM
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Joined: Jan 2003
Posts: 5,446 Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,446
Indiana
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I just checked the Demon web sight and found that a stock 850 MD comes with 85/93 jets. Your 72/80 is almost what a 650 Speed Demon comes stock with. Have you checked your plugs to see if you are lean? Have you tried a 035 squirter? Have you checked to see if fuel comes out of the squirter AS SOON as the throttle moves?
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: Stumble from my 850 Mighty Demon?
[Re: dduster73]
#69352
06/07/08 08:16 PM
06/07/08 08:16 PM
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Joined: Apr 2007
Posts: 1,261 ILL
mark7171
pro stock
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pro stock
Joined: Apr 2007
Posts: 1,261
ILL
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Quote:
73 Duster 440/4speed 9.7 compression rebuilt engine 1 3/4 TTI headers. Stock Holley Street Dominator intake.Comp Cams XE 285 HL hydraulic camshaft 285-297 241/247@.050 545/545 @1.5 rockers.850 Demon carb has 72/80 jets,31 squirters and 4.5 powervalve with 8.5" of vaccuum @800 rpm.Had a 6.5 power valve but no change.Car will stumble @ part throttle when pulling away from a light.Seems to do this at anything under 3000 rpm.Any help appreciated. Thanks ,Dave
that is not street car specs. i find this makes me laugh.
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Re: Stumble from my 850 Mighty Demon?
[Re: mark7171]
#69353
06/07/08 08:20 PM
06/07/08 08:20 PM
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Joined: Nov 2007
Posts: 21,909 Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,909
Kirkland, Washington
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Quote:
your gonna get rolled.
whats your timming like? itial+mechanical+vacuum...
let me guess ... no vacuum advance....
you have a race car. the transitition circuit probably wont cover the demand, and it will be a WOT machine. Quote:
Huh????? What part of his specs scream "race car only" to you???? While the cam is a little larger than I prefer on a street car, I have run bigger. And with less vacuum (6.5")
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Re: Stumble from my 850 Mighty Demon?
[Re: dduster73]
#69354
06/07/08 08:24 PM
06/07/08 08:24 PM
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Joined: Jan 2003
Posts: 5,446 Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,446
Indiana
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""The 850 Mighty Demon came out of the box with 80/88 jets"" I just checked again and the 850 "AD" Mighty Demon comes with 80/88 jets and the 850 Mighty Demon comes with the 85/93 jets. Does this carb have annular boosters? Is this carb a blower carb by chance? ------------- I found this to be a #5563020GC 850 Mighty Demon Annular Mechanical Secondary carb. This helps explain the smaller jetting. The annulars pull alot more fuel thru smaller jets. If your plugs look good, then I would try raising the squirter size .
Last edited by YO7_A66; 06/07/08 09:05 PM.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: youre right it could be?
[Re: YO7_A66]
#69355
06/08/08 12:09 AM
06/08/08 12:09 AM
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Joined: Apr 2007
Posts: 1,261 ILL
mark7171
pro stock
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pro stock
Joined: Apr 2007
Posts: 1,261
ILL
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my comments are a little raw. your engine that you built should be streetable, because as they say " it runs on pump gas " .
people do some strange things to there cars.
what package did you try to come close to ... or in between ?
look at holleys systemax I,II. or edelbrocks performer, torquer II, or RPM. OR the mopar performance packages in the back of the jobber MP catalogs. mp's suggestions goes to 8.90's i believe...if you still cant come close look at Trickflo's twisted wedge package offerings.
Last edited by mark7171; 06/08/08 10:08 PM.
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Re: youre right it could be?
[Re: dduster73]
#69358
06/08/08 01:48 PM
06/08/08 01:48 PM
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Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
master
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master
Joined: Dec 2003
Posts: 5,314
Carstairs, Alberta, Canada
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Quote:
Yes it has annular boosters.Will try to add more inital timing its at 15* now. Then i'll try 35&36 squirters.If that makes no difference will go back to the 80/86 jets. The cam was chosen by Comp Cams reccomendation.Thanks to all for the advice. Dave
I think the timing is your main issue.
15 is waaaaaaayyyyyyy not enough for that cam duration, and that compression.
Your inital should be more like 22. If you can set it up for 22-24 initial with 35 total, all in by 2800, I think you will be amazed at the difference
FWIW...I have less cam (242@50) with more comp (10.7:1) and I run 24 intial.
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