Opinions on Demon carbs vs Holley

TexasRoadRunner68

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Looking for some input over my carb choice. I know Holley owns Demon now, and that demon started as a company trying to improve Holley carbs. I’m a huge fan of motor trend, and I know the engine masters guys seem to love the Holley HP.

Any one experienced with the 750-850 demon carbs?
 

Dennis H

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850 Demon on the 440 prior to efi. Worked good.
 

Rusty knuckles

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I have no opinion either way except to say the engine masters guys are either getting free parts or money or both to use and mention the stuff they use. It's not because it's the "best."
 

33 IMP

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Bought a prehistoric demon (gold claw, replaceable sleeves) from a buddy, off his 408 Ford. Put it on my 406, never even pulled the bowls off, eventually ran 6.32/ eighth. I thought it was set up with the 850 sleeves, turns out they were 775 cfm. I got two other sets of sleeves with it, never bothered with them.
I like it.
 

Geoff 2

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What I'd be wondering: if Hs are so good, why is every man & his dog making 'better' ones....
 

Moms68

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I had Demon, and couldn't get it dialed in at idle. switched to a Quik fuel and haven't looked back.
 

451Mopar

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I think the Demon had the adjustable idle air bleed under the filter stud?
Never used a Demon, but I don't see much difference (bsides the air bleed, I think the fuel bowls cover the metering blocks?).
They pretty much work the same way, you just need to tune either to your engine combination.
 

4speed68rt

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The Demon is just what it is supposed to be, an improved Holley. Much more tunable. I like my Demon.
 

TexasRoadRunner68

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I have no opinion either way except to say the engine masters guys are either getting free parts or money or both to use and mention the stuff they use. It's not because it's the "best."

After seeing some of Dulcichs work, I would say that guy knows more than most when it comes to vintage mopar. Steve Brule is also great at his craft. Freiburger is good as well, but I’d say not as masterful as those two.

Most of their stuff is from Westech or is paid for by the show I’m sure. They test stuff and will tell you and show you how it compares…I don’t think they’re hiding something.

They have even said brawlers perform as well basically, but they normally go for the Holley’s because they have them around.
 
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GTX JOHN

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Westech is one of the top Dyno Shops in the country.

Demons are more tunable but either one will work great and
I used them both....

The problem is you must be will to work with them on your particular
combination. The is no "Silver Bullet" that you can bolt on anything and
it will be optimal out of the box.
 
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dvw

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All carbs are tunable. To what degree depends on the tuner. There are so many aftermarket Holley based parts that most of the original Hooley stuff isn't even used. If you were buying new this is the way to go. However in a street application? A used Holley with a good rebuild and a little bit of knowledge will go a long way. Race carb? For the price and service you will be hard pressed to find a better builder than Mark Whitener at Lightening Racing Carbs.
Doug
 

451Mopar

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The quality control of the last few Holley carbs I bought was pretty bad. Alot of debris found in the carb and metering block jet well area.
Now I take the carb out of the box, tear it apart, and clean everything.
While apart I check the bleeds and restrictor sizes with a pin gauge set.
If the metering bock don't have the screw in bleeds and restrictors and needs additional tuning, I put an aftermarket billet metering block in for tuning, then when the tuneup is good, I will duplicate the bleeds and restriction sized in the original metering block with pin drills.
I will dial in the idle mixture, throttle blade position, and transition circuit first.
If I want to really get the jetting dialed, I will use power valve block offs and a wideband O2 meter to tune the cruse / light throttle AFR around 14-15, then put in a high vacuum power valve, and check the AFR under load. Adjust the power valve restriction sizes to get a good rich setting around 12.5 to 13.0 under load.
Then put in the correct size power valve, and work on the transition circuits, accelerator pump discharge nozzle siza and cam profiles, and vacuum secondary rate if a vacuum secondary carb. If it has a choke, adjust the choke too.

FWIW, I have only had one carb that worked halfway decent out of the box at this altitude. It was an old Holly HP 1,000 cfm on the 451 stroker engine.
 

PRHeads

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I haven’t run any recently assembled Demon products.
When they first came out, the shop I was running the dyno at was a BG dealer.
And BG had a great dealer program.
You could make money on a carb selling it for the same price as Summit.

I don’t know how many I tested, but I know exactly how many ran at least “pretty good” ootb. One.
Most were way way off ootb. The base calibration just didn’t ever seem to be right..... for anything.

Multiple times, after spending several hours on the dyno trying to sort one out...... a swap to some plain Jane Holley would cure it.

Eventually it got to the point where it wasn’t worth the hassles of selling them, so we went back to selling Holleys for most applications.

I had an 850 Mighty Demon that I took in on trade.
It had been passed around a few times from what I gathered.
The tune up that was in it when it came to me didn’t make any sense.
It’s like someone threw some jets and air bleeds in it to make it “complete”.
By that point I’d worked with them enough to have an idea on a baseline calibration.
I got it sorted out on the dyno and ended up using it for a few years as a dyno mule.
That was probably the Demon carb that I was happiest with overall.
I was pretty “well stocked” with carbs at one point, and as I thinning out the herd....... that one found a new home.
 
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Butch Harley

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don't ask me I like a lot of them

100_2204.jpg
 

furyus

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I have a 750 race Demon on my Sport Fury. It has been excellent.
As for performance, it ran just as good as my buddies' tricked out Holley 750.
 

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