Mighty Demon or Holley HP??? Which is better? - Chevy Nova Forum
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Old 21st-November-2006, 03:44 AM   #1
Scott C
 
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Mighty Demon or Holley HP??? Which is better?

Which carb should I go with. Heres my engine combo:

SBC 383 9.81 compression
Dart 200 cc Iron eagles
Comp Cam x-treme energy 268
Performer RPM Air gap
MSD dist, and digital 6 plus box.
Sportsman fogger 150 shot
turbo 350 trans with 3000 stall converter
9 inch rear with 3.90 locker
26" tall tire in a 64 nova.

I was thinking a 750 cfm carb should work well but can't decide on a Mighty Demon or Holley HP carb. Or is there a better choice all together? Should i stay with mechanical secondaires or switch to vac.
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Old 21st-November-2006, 05:24 AM   #2
rodent
 
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I bought a couple of MD's recently, they work fantastic and do what they're supposed to but........machine work leaves a lot to be desired
If i had my $1700 to spend over again, i'd wait till i had more and go Holley. I've had lots of Holleys over the years and had no real prob's, buy a couple of BG's for the first time.......disaster

Maybe next year.

cheers and good luck with your choice.
jim
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Old 21st-November-2006, 07:29 AM   #3
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Let me start by saying that this is my opinion and in no way am I a carb expert (you will not find my name on any carb). I have a 750 Mighty Demon on my car now and it does a great job. I will agree with rodents statement about the machine work leaving a lot to be desired. Saying that I also believe when you buy a new carb ( holley or demon) you should disassemble it and check all orfices before installing.

I dont think you can go wrong either way ( holley or demon). I like mech. secondaries myself. One other bit of advice make sure what ever you buy that it is adjustable (screw in airbleed, screw in idle feed restrictors). That way you can set it up for your current motor and any future engine combo's.
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Old 21st-November-2006, 10:34 AM   #4
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Let me tell you my experience with BG/Demon Carbs.

First off my engine combo:

468 w/10:6/1 compression
Brodix BB2 Plus heads 245/ with 119 cc chambers
Brodix HV2000 Single plane intake
Comp Cams solid roller 262@ 50 with .652 lift

Ok that said. When I finished my engine I looked at all the demons and the applications listed for them. I went ahead and bought an 850 speed demon.

Problems:
On startup, the carb flooded like crazy. I'm not talking a little rich, I'm talking about eye watering flooding. I checked my fuel pressure, adjusted idle mixture screws and idle eze plate. It still flooded.

Called demon tech support before I did anything else.
Tech support guy A said that an 850 speed demon was WAY to much for my combo and said it was for engines with 500+ cubes and told me I needed a 750 mighty demon.

Fair enough. I bought a mighty demon 750. Put it on and the car ran fine.
However, when I ran against a buddy of mine with nearly the same setup only he had cast iron heads and a dominator he beat me by a full second. Yep thats right. I ran a 10.0 and he ran a 9.0 and thats 1000' friends. I'm not saying it is all the carbs fault because I have **** headers with 1 3/4 primaries and 2" exhaust which is soon to change. Still yet, with my engine setup in a 71 nova with t-350 3000 converter (which isn't quite enough) and 4.11 gears I should be ripping off the 1000' at a low 9 to high 8 without an issue. But nope. 10.0 @ 104 mph with a 1.6 60'.

OK Problem 2.

Sold the 850 to a buddy of mine from the track.
Flooded his engine too.

Get this.............
He pulled the bowls off and their was metal shavings all inside the bowls.
Not to mention that whoever tapped the main body for the baseplate screws went to deep and drilled a hole into the powervalve orifice.

I call BG and they give me an RA to send it back.

They look at it, clean it up and say there are NO PROBLEMS!? And that the hole will not hurt anything.

They send it back to me and I have to give my friend his money back.

I call support again and get guy B.

Guy B tells me that guy A is crazy and a 750 isn't nearly enough carb for my application.

I decide to try to run the 850 again to see if it is still flooding.

Guess what? It runs perfectly now even though they said no problems found.

Runs alot better than the 750 thats for sure.

So I sell the 750 and now I'm debating putting on a 1000 Race Demon or a Dominator this winter.


Overall, when the demons aren't full of metal shavings and **** they are great.

But like the others said the machine work isn't that great.

Don't make my mistake. Pull the bowls off and check for anything unusual prior to startup.
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Last edited by MuscleDreams; 21st-November-2006 at 10:40 AM.
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Old 21st-November-2006, 11:25 AM   #5
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I've also heard that BG's quality control isn't great. I think that may be why Summit no longer sells BG carburetors. But, I've also seen tests with dyno runs and apparently, BG carburetors will put out more HP if tuned properly. I have a 750 Speed Demon on my Mach 1 and it runs fine, but when I tried to adjust the floats, fuel spilled out of the adjusting screws. I'm guessing BG buggered the o-rings on assembly. No big deal. My Nova is getting a Holley HP 1000, only because I got a great deal on it.
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Old 21st-November-2006, 11:32 AM   #6
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Quote:
Originally Posted by The_Dude View Post
I've also heard that BG's quality control isn't great. I think that may be why Summit no longer sells BG carburetors. But, I've also seen tests with dyno runs and apparently, BG carburetors will put out more HP if tuned properly. I have a 750 Speed Demon on my Mach 1 and it runs fine, but when I tried to adjust the floats, fuel spilled out of the adjusting screws. I'm guessing BG buggered the o-rings on assembly. No big deal. My Nova is getting a Holley HP 1000, only because I got a great deal on it.
I have the real scoop why Summit no longer sells BG carbs. Summit would sell you a 1000 King Demon, regardless if your setup really called for a 650 Mighty Demon. Lots of unsatisfied customers, and as a result, the carbs were then sent back to BG, when there was nothing wrong with the carbs in the first place. BG told Summit to kiss off and pulled his carbs out of there.
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Old 21st-November-2006, 11:43 AM   #7
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Another vote for the mighty demon! I run on one my 383 and it performs great. Just make sure you get the 650 mighty demon. I originally started out with a 750 speed demon and it was just too much carb. They guy at demon explained that the 650 flows a bit over 750 and the 750 flows over 850. Why are they rated this way you ask...i have no idea
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Old 21st-November-2006, 11:43 AM   #8
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Old 21st-November-2006, 11:50 AM   #9
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Quote:
Originally Posted by StrokinIt383 View Post
Another vote for the mighty demon! I run on one my 383 and it performs great. Just make sure you get the 650 mighty demon. I originally started out with a 750 speed demon and it was just too much carb. They guy at demon explained that the 650 flows a bit over 750 and the 750 flows over 850. Why are they rated this way you ask...i have no idea

Funny you mention that. BG Tech support told me a 750 mighty wet flows 930 cfm.

Sounds like they pull a number out of their rear. Anyway, if that was the case then why not rate it a 930 mighty demon?
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Old 21st-November-2006, 11:53 AM   #10
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Quote:
Originally Posted by MuscleDreams View Post
Funny you mention that. BG Tech support told me a 750 mighty wet flows 930 cfm.

Sounds like they pull a number out of their rear. Anyway, if that was the case then why not rate it a 930 mighty demon?
Why? It's marketing...."our 750 outflows Holley's 850".
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Old 21st-November-2006, 12:06 PM   #11
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Aye! Didn't think about that.
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Best time 7.14 @ 98 1/8th 9.19 @ 110 1000' 1.58 60' Car Weighs 3320 without driver, 3570 with
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Old 21st-November-2006, 12:09 PM   #12
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I don't have any experience with B/G so I can't comment yea or ney. I have read about similar problems on other boards. I just picked up a Proform 750 DP from racingjunk dot com that is a work of art. Will it run better than a Holley 750 DP set up the same...? Dunno.
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Old 21st-November-2006, 12:32 PM   #13
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I've owned two Demon carbs, one Holley carb, and now my ProSystems carb (based on a Holley). The Demon carbs are a nice looking carb. I got that Speed Demon tuned pretty well, but my new ProSystems carb is in a league of it's own IMO.
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Old 21st-November-2006, 12:44 PM   #14
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Old 21st-November-2006, 01:20 PM   #15
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Well, I have a Race Demon RS(w/sleeves from 775-975cfm) 1050 Dominator, and a 750 Street HP Holley. Of all of these, the Street HP impressed me the most--bolted it to the junk 350 and it works great right out of the box. I feel just the opposite concerning the Demon quality; the machine work on mine is far better than what I see on the average Holley piece, BUT, it took a long time changing sleeves, boosters, air-bleeds, etc., before it would run as fast as an 850 DP Holley. From my experience I tell people you're almost guaranteed to lose 20 H.P. bolting on a Demon over the same cfm Holley. All the magazine guys use Demon stuff these days because B.G. will kick out free stuff by the boatload. The magazines won't do A-B testing against each other so you don't make one look bad. Keep an eye on MaxChevy.com, they are going to do some testing that will show what works and what doesn't without regard to making the other guy look bad. I tried to get Hot Rod or Car Craft or Chevy High to do it, but you can't bite the hand that feeds you!
I was talking to a well known local carb guru the other day and he has a couple Demons sitting on the shelf that he couldn't get to run right no matter how he tried-he gave up and replaced them with Holley's. I told him he could give them to me but............
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