I run a road demon jr 625, and more than happy with it`s performance. I delt with edelbrock carbs a few times and I honestly don`t like them. But they get the job done when needed, if someone wants one for day to day driving by all means I tell them go for it. Of all carbs I perfer a Quadrajet, as Nairb said, one of these set up correctly is hard to beat, the small primary`s make for outstanding throttle responce, almost as sensitive as fuel injection. And when max performance is needed the massive secondary`s flow lots of air, the only reason why I`m not running a Q-jet is because almost everyone I get my hands on now someone has let it sit in the weather and it`s ruined. I was going to go back to a Q-jet on my next project, but decided I`ll just retain the Demon. Demon`s can be a pain to tune, I`ve said that many times, but it`s not that difficult honestly if the instructions are followed to the T, I learned you can`t skip anything on tuning a demon or it won`t be right. I had tuned many a carb for many a years, and it`s been the only one I had to read the instructions to tune it. As for BG tech support, talked to them twice, when I lost my instruction booklet, they sent me another along with a video, and many stickers all for free, can`t beat that. I liked the Demon over Holley`s since most Holley`s I`ve delt with, I don`t like there poor quality control.

Can an Edelbrock 750 cfm keep up with BG or Holley 600 cfm??? in the same combo. I`m not trying to be funny, but Edelbrock has a bad rep for carbs.

( I have a similar combo, my hi-performance machinist told me to DUMP the Edelbrock but I did see a huge difference going from a 600 Edelbrock to the 750 Edelbrock. I went with Edelbrock because my 750 cfm was less than $200 from Jegs , yes rebuiltand yes trying to skin the cat as cheap as possible)

http://www.edelbrock.com/automotive...s/1412graph.gif

Edelbrock 800 (#1412) vs. Holley 750 vac. secondary (#3310), sorry, I just had to add fuel to the fire!!!

Repeating what I posted on the original thread........excellent post, you've gained alot of respect with the original honesty and alot more with the dyno results.

Keep up the good work.

Tell B. Grant thank you (from all of us)

?I wasn't a slammer I hope.

Lots of interesting info in this thread. BG@Tech brought up a very good pooint in selecting the right carb for the application and it this probably one of the most overlooked bit of info in our community. How many of us have been guilty of going to our favorite salvage yard and picking up a good looking carb from that 455 Buick and ploping it down on our 327 powered Camaro and wondering why it ran like a dog? A Q Jet comes in many different sizes and configurations, just like Hollys, Carters, Edelbrocks, Demons etc. I was looking to replace the QJet on my 327 and looked at Edelbrock. I almost got a nose bleed studying the many different numbers to try to make a logical selection. I gave up and rebuilt my Carter QJet!! Next time, I'm going to EFI the sucker!!!

Trees

from... Is there any advantage in running a BG speed demon over an edelbrock performer carb? thread...

quote:
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Originally posted by red65mustang
it is "not smart" to say a Demon flows more CFM than a Edelbrock.
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quote:
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Originally posted by red65mustang
we could have tried to guess how much more the Demon was going to produce!
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from another thread...

quote:
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Originally posted by red65mustang
swapping a 600 for a 750 doesn't drastically change anything on a given street motor.
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So what exactly do you believe red. You seem to flip-flop more than Kerry in the presidential elections. You seem to agree with BG's results that different brand carbs can produce different power results on the same engine (after calling him "not smart") yet you say that changing from a 600cfm to a 750cfm carb will make no real difference on a street engine (which is basically what BG's test engine was "basic 350 test engine with a .220 @ .050” cam, Dart Iron Eagle heads, and dual plane intake manifold"). So you're then implying that we should put 750cfm double pumpers on all our 305 Chevys and 600cfm carbs on our 454 big blocks since it makes no real difference and won't really change anything. Just curious.

i am a proud supporter of demon carbuteration. i believe it to be a superior product, now i know it is with management like this.

thanks for the time you spent, backing up your great product

Hey BG Tech what does a Vortec Six Shooter go for?

Rick458,

Actual retail pricing is set by our distributors, but you'll normally find them around at $2400 for the complete system. That includes the intake, carburetors, linkage, fuel rails, gaskets, air cleaner, and hardware.

The guys at Scott Shafiroff racing engines just did a conventional unit on a 434" SBC and made about 525HP, and 575 Ft/Lbs Torque. With only minor adjustments to the setup. We've had great results with the way these systems have performed.




To make it a little easier we've got a selection guide that we use. Here is a link to it. http://www.barrygrant.com/demon/default.aspx?page=5

There is an excellent link/article to help you understand the basics of CFM versus TQ on this board (somewhere).

They started with a 350CFM carb and progressively tested thru 850CFM on the same 350 cube street motor with TQ and HP results for each carb.

Hope that info helps you.

(somebody help please....where the heck did I read the Chevy info/link...which thread)

Here is an article similar to what you describe, but they start out with a 390 cfm and go up to a 1000 cfm. It is more for showing how any size carb will work, but there are consequences for going overboard on size in either direction affecting throttle response, horsepower, etc.

HERE you go.

It is a real good article, and it shows that you must know what your intentions are for your vehicle. It gives two answers as to the"What size carb should I use for a 383 SBC making 440 hp/tq". A 750 for a daily driver, and the 830 if the car is dedicated more towards a racer are the answers. It also shows that "For those readers who like to crunch numbers, there is a commonly used formula for determining carburetor size, but it provides only a rough starting point as all the engine's variables are not taken into consideration." Something that has been hotly debated in a few threads lately. That formula is a safety net, but it takes dyno time/testing to determine what is best for each application and it's intended purpose.

Yes I remember that link from way back and it basically showed just what wildman926 so eloquently put. Depending on what your intentions are it definitely makes a difference what size carb you should use. If I remember correctly without even re-checking the link it also should progressive increases in power as carb sizes were increased but after a certain point you started to lose drive-ability. Now how does that agree with your statement...



As far as I see it power is power and most guys that I know would rather have 375hp than 345hp by using the right carb. That test was also done to show how different carbs would react on one engine. Your statement implies that carbs make no difference on any engine on the street. Like I said I guess you would put a 750 double pumper on a stock 305 Chevy and a 600cfm carb on a 428 Cobra Jet Mustang. I'll tell you what really amazes me is how every answer you have for everything is based on what someone else said or wrote (this book said..., Max Keith said..., that link said...). Pretty sad.

thanks wildman, that's the article I was looking for

dmorris,

600cfm=458ft/lbs. 438HP
650cfm=461ft/lbs. 444HP
750cfm=461ft/lbs. 444HP

You gained .0065% TQ and .0135% HP

Sorry you don't understand how this does apply "to any street motor". That one is pretty darn tight (3 ft/lbs). Not what I would call typical.
Is it the BEST CFM choice for any cubic size motor, obviously not from the article. Or from the basic carb selection guide on the Holley site.

Your last comment, I'm wrong (?) for backing up my posts with facts, sorry, no reply.

Guys this is an excellent article, but there are things it does not take into consideration. Since the testing was done on a water brake dyno, you can over carb an engine without it showing up as bad. The computer will sense that the engine is not accelerating, and it will decrease the amount of load going to the brake, allowing the engine to accelerate. This does not show you how these would work in terms of actual drivability.

Depending on what vehicle this engine is installed in, and the rest of the drive line, (transmission, converter, gear ratio, tire diameter, etc.) and of course usage it may vary what carburetor would perform best on this engine in the real world. Put the engine they testing in a 5000 lb lead sled with an overdrive transmission, or a 2000 lb kit car with a 6 spd you’ll wind up with a different carburetor to get the best overall performance.

Some of you guys are funny, LOL.

It really isn't that difficult. A Carb. is part of the overall "COMBINATION" a good matched combo will run the best. Pick a carb for what you will use the engine/vehicle for.

BG and Holley style carbs just make more power than the Carter AFB/Edelbrock carbs. This is not a knock on Edelbrock/Carter. They didn't build their carbs to "out perform" brand H or B. Their carbs work just fine too and are perfect for some applications. Examples would be mild street rods and or people that don't know how to tune a carb. You can be pretty far off with one of the Edelbrocks and the car will still run "ok". The same is not true for a Holley or BG but, when either of them are tuned properly the Edelbrock/Carter just can't hang when it comes to performance.

Of course there is always the Q-jet die hards. You can have them all to yourself. I wouldn't take one for free. It's not because they are bad carbs (besides being ugly). I have just never had success tuning them (user error I am sure).

Bottom line is you have to match the carb to the combo and you have to know how to tune whichever carb you choose, if you want the most out of it.

Royce