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Speed or Mighty Demon 850?

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69-CHVL

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Discussion starter · #1 ·
Continuing my quest to try every carb know to man :D, figured I've give one of these a shot. Which is better for a ~550HP BBC, manual trans?
 
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#2 ·
Hi Vince, I've been using the 850 mighty Demon for 3 years now. It has worked well for me, but I do have an automatic. I have also notice that a lot of the bbc builds in the magazines they using the mighty demon. I would like to barrow a 950 or 1000 hp and try one on the 1/4 mile sometime to see if it makes any differance.
 
#3 ·
Vince,
I ran a mighty demon and although it was crisp off idle it did not work well on the strip.
I put on a 4150 hp and it picked up almost 4 tenths right out of the box with NO tuning whatsoever.

I'd not waste my money!
 
Discussion starter · #4 ·
chevguy65 said:
Vince,
I ran a mighty demon and although it was crisp off idle it did not work well on the strip.
I put on a 4150 hp and it picked up almost 4 tenths right out of the box with NO tuning whatsoever.

I'd not waste my money!
Click to expand...
:eek:


Wow. Guess I'm reading too many magazines!

Guy here at the local chassis dyno says the demons make more power, as does my hero Joe Sherman.

What happened at the strip with the carb? Erratic metering?
 
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#5 ·
It all depends on if they are tuned up right or not, regardless of the manufacturer of the carb.

I've used speed demons and Mighty demons. for a non cold weather car, I'd just go up to the mighty without the choke horn. I think that the 850 may even be too big for you. The Demons are supposedly flowed differently thanholleys, so they flow more for the same rating. Demons are wet flowed, and holleys are dry flowed. A 750 Demon supposedly flows somewhere around 850 or 900 "dry" cfm.

If you try the demons, just take them apart before you put it on the car, and give it a good cleaning. BG is notorious for leaving small chips/shavings in the bowls etc.

Great carbs other than needing to clean them.
 
#7 ·
yea if you can "SEE" where the shaving are, why risk it when the holleys dont have those issues and are proven performers.

Way back i purchased a brand new Silver Claw that came with the fuel bowl inserts not machined on the top side ( meaning only there lower side had threads ). Ended up sending it back and getting a 1000HP and that was the best carb i ever owned.

ON this engine i purchased a King Demon and after months of working with Barry Grant never got it remotely close to right at idle or the strip. The best it could manage was 7.0 in the 1/8 with Open headers. My cousin purchased an old 1050 at the track for his build that looked like it had been dragged behind a truck on the way to the track. I bolted it on and picked up 3 tenths oh and the front wheels for the first time ( through mufflers which stiffled the engine ). Then i purchased my own read deal AED Pro Street Dom and picked up another 2 plus tenths.

One of my friend purchased a blow through one from them that was all messed up as well ( twice ).


BG has a nice design and some good ideas however their quality control is unacceptable. I loved the king demon from the thick billet base to the large sight glasses and the overall feeling of stronger components but the one i had sucked.

Why risk it grab a 1000hp and youll have that carb for years and it will be healthy enough for you next build as well.
 
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Discussion starter · #8 ·
I called BG for the heck of it. They recommend the 850 Mighy annular, as the regular downleggers will flow close to 1000cfm and they are too big for what I'm doing.

I have a 950HP that runs excellent, but again to rich for everyday driving.
 
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#9 ·
what adjustments have you tried on it? do you want to sell it?
 
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#10 ·
My 461 has a little bigger SFT cam than yours at 241, 249 @ 0.050 with lift around 0.600. I tried a 850 speed demon first, and then changed to a 850 mighty demon. The mighty demon has the option to tune the idle air bleeds, and the idle feed restrictors. My problem was idling too rich. With a little tuning, the motor idles (in gear) and runs great. This is the first time running a demon carb and I love it. Whatever brand you run, I suggest using a carb where you can tune the idle and low speed circuits.
 
#11 ·
The shavings issue has already been addressed many times on here and there was numerous steps taken to correct it. In regards to cars making less hp or running slower it has been our finding in most cases unless something is terribly wrong with the particular carburetor that they are the wrong size and/or series for the motor. Many guys will either put too big of a carburetor on a motor or try to put the entry level carburetor on the wrong application. Properly matched up the Demon will make more hp and use less fuel.
 
Discussion starter · #12 ·
Shawn Gilbert said:
what adjustments have you tried on it? do you want to sell it?
Click to expand...
Everything. Jets, IFR's, bleeds, you name it. I can get it leaned out, but it destroy's the killer performance of the carb. I think it has to do with the "special" high flow metering blocks.

My quest in life is to find a carb that give 950HP performance, with the 3310's ability to cruise leaner.

Figure I'll keep it for race only.
 
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#13 ·
I have been useing a 800 annular booster Mighty Demon for the last few years.This was reccommended by Tech @ BG,and it has proven to be an excellent carb.There were no QC issues with it,all it needed was re-jetting.Its nice & responsive,and works good at the track.
Guy
 
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#14 ·
69-CHVL said:
:eek:


Wow. Guess I'm reading too many magazines!

Guy here at the local chassis dyno says the demons make more power, as does my hero Joe Sherman.

What happened at the strip with the carb? Erratic metering?
Click to expand...
Carb was professionally tuned.
And for a street carb the mighty demon was fine.
It was a turd however at the track.
That was made evident in the 4 tenths I picked up by swapping them out.

imho the holley is much better and after reading an article on another site from BG himself, I would never run anything BG on my car EVER again.
 
#15 ·
chevguy65 said:
Carb was professionally tuned.
And for a street carb the mighty demon was fine.
It was a turd however at the track.
That was made evident in the 4 tenths I picked up by swapping them out.

imho the holley is much better and after reading an article on another site from BG himself, I would never run anything BG on my car EVER again.
Click to expand...
What does "professionally tuned" mean though. If you aren't doing it with an a/f meter you never really know what the tune is. Pro-Systems and all of the other "mail order" companies make their best guess, but if the carb isn't on the car, being loaded exactly like each particular application needs, the carb will simply be a best guess.

I'm not trying to be a nay-sayer, but I have learned a TON since I have started tuning with an air/fuel meter and bought some billet fully adjustable metering blocks from BLP to put on my mighty demon. If you know what your car is doing, what it feels like, and where it goes lean and fat, you can adjust it much more easily than guessing just based on seat of the pants.
 
#18 ·
Heckeng said:
What does "professionally tuned" mean though. If you aren't doing it with an a/f meter you never really know what the tune is. Pro-Systems and all of the other "mail order" companies make their best guess, but if the carb isn't on the car, being loaded exactly like each particular application needs, the carb will simply be a best guess.

I'm not trying to be a nay-sayer, but I have learned a TON since I have started tuning with an air/fuel meter and bought some billet fully adjustable metering blocks from BLP to put on my mighty demon. If you know what your car is doing, what it feels like, and where it goes lean and fat, you can adjust it much more easily than guessing just based on seat of the pants.
Click to expand...
Call and talk to Matt Compton owner of Performance Solutions in Boise Idaho.
Ask him what professional tune means, he is the one that tuned the carb and engine.
I am sure he used all the tools and tricks, but still you need to talk to him.
 
#19 ·
If he tuned the carb on the car, then that is definitely a step in the right direction! You hear so many people who mail their carb to somebody who claims that if you tell them the cam grind, they can tune the carb to exactly what they need. I call BS. Sure, sometimes they may get it to run well, sometimes not, but without seeing the whole system it is just a guess on their part.

I'm not trying to cast doubt on your particular carb guy, just trying to find out how there can be a .4 second difference in performance if the carbs are basically the same! Given, your boosters could have been different styles etc, but the fuel passages and air passages are basically the same on all modular carbs.

For the original post, I say don't buy the Mighty Demon, but get some BLP metering blocks and have the carb REALLY tuned by someone who knows how to tune the bleeds and various restrictors, not just jetting.
 
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