need help picking carb,getting a mighty demon for sure.......bg support says 650 cfm what do you guys think????
350 60 over,10.2:1 cr,pro actions 200/64cc,perf rpm(soon torker 2),280h
th400,4:11's.i see people using 750's on 350 sb's
why?is there any benefit??will i be fine with the 650 mighty demon???please help we all know you cant return once you fill the bowls.....
shane

A 650 mighty demon would be perfect! 750 would leave room to grow 383,406.

700 dp holley

getting a mighty demon for sure.......

A 650 double pumper would be a perfect fit for your combo IMO, but you could get away with a bigger vacuum secondary carb if you're planning on doing some upgrading later on. You won't get the throttle response from a bigger vacuum secondary carb that you'd have from a 650 DP either. Most folks get tempted to go bigger, but the smaller carb usually works better every time. I didn't know you couldn't return a carb after trying it, and all the Holley carbs I bought came with gas residue in the bowls from the factory. :confused:

Originally posted by ovelle:
need help picking carb,getting a mighty demon for sure.......Sounds to me like your mind is already made up? I would personally rather see you use a Holley. Having owned and tuned several of each, I can tell you that in my experience without fail the Holley is a better carburetor. Every demon I've owned (750 road demon and later a speed demon) was nearly impossible to tune. Both demon carbs idled pig rich! Perhaps the mighty demon is different than the ones that I've tried. I can tell you that at the tracks I frequent the anti-demon sentiment runs very high, and that has nothing to do with my being in the bible-belt either :D

I would spend that hard earned on money on a comparable Holley. The Holley Street Avenger 670 would be a nice street/strip carb for your application, IMO. If you're looking for something to grow into look no further than the Holley HP series carbs. Best money you will EVER spend, guaranteed.

my $0.02

Here is my 0.02 cents!

Your combo is probably a making more power than my combo because of the heads but my combo
is also a 350 60 over with a 274XE cam, ported heads, 700r4 w/2400 stall lock-up, 3.73 gears
RPM Air_Gap manifold, and Speed Demon Carburetor 650 Mechanical Secondary. The Engine was chassis
Dyno at 410 Hp flywheel and 448 lbs of torque and if your engine is more or close to this
horsepower range than the Speed Demon 750 are recommended but as mentioned before the 650 will
do also may be better for street, I however have to change my rear jets from stock #78 to #80
because the engine was cutting out at the track when running quarter miles times, regardles I ran
a 13.6 on street tires. I really don't know the difference between the Mighty series and
the Speed series demon carburetor, but as far as the 650, 750 the ventri sizes are 1.28(650)
and 1.40(750) and the primary and secondary jets are #76(p) and #83(S) compared to #70(p)
and #78(S) in the 650.

Now as far as carburetor opinion Demon versus, Holley, versus whoever! Regardless if
someone had trouble tunning them and they swear by the name both Holley and Demons are great
and I have experienced both and very successful. I do however favor Demon because I made
more power with the Demon compared to the Holley and I guarantee if you go Demon your
car will perform closer to its potential. Have you thought about the Speed Demon series?

Originally posted by Spawn22:
I however have to change my rear jets...
because the engine was cutting out at the track when running quarter miles times...I think that proves my point :D I've never had a Holley that was so far out of calibration that it performed like you're describing your Demon carb did right out of the box! I have on the other hand had two Demon carbs that did EXACTLY as you decribe.

Seriously though, I'm sure the Demons are good carbs and can be tuned to perform well. However in my experience the Holley carbs perform better out of the box.

As to your comments about your car making more power with the Demon vs. the Holley, care to share ALL the test data that you used to arrive at this conclusion?

Go for the Demon for sure, Holleys are way hard to tune. Ignore the naysayers, sometimes the old dogs are reluctant to let go of something theyve used in the past regardless if there is something far superior such as the Demon. Guys at the track I frequent have almost all switched due to the holleys not performing. Demons seem to be way more consistant in the 1/4

I have used holleys and demons and even the old BG claw series...they all have their good and bad points.

The best thing about Demons is that you can pick them up cheap because people get frustrated and just put holleys on.

But my 66 ran the best with a BG silver claw.

Rob

I think that proves my point I've never had a Holley that was so far out of calibration that it performed like you're describing your Demon carb did right out of the box! I have on the other hand had two Demon carbs that did EXACTLY as you decribe.
Maybe your engine doesn't make power :rolleyes:

Kjet tell me your kidding because if your serious I can't you serious. I don't know what engine your running and I am sure it maybe great but a performance carburetor is made with the calibration and adjustments in mind. Good to hear you got your holley to work with your engine without tunning, but to imply that holley's work right out the box and does not experience similar problems as I do then I think you need to search these archives and educate yourself because the majority of the problems were from people using holley. This is not about Holley versus Demon because they are very similar structured carburetor thus many parts are interchangible, this about tunning your carburetor to your engine needs. I have an opinion and you have an opinion about carburetor but listening to the " I can't get my Demon to idle or run" slogan come on! I don't want a carburetor that bolts on with no adjustment because that mean your not reaching your engine potential. Maybe you don't understand Demon carburetor thus you come to your opinion.

As for my comparison of Demon and Holley, Engine Dyno my engine with Holley 650 Double pumper with stock jets made 10 less HP then Demon 650 with its stock jets #70 primary #78 secondary I will email you the dyno sheets are would you like them to be posted? Once again this is not a Demon versus Holley but more of the " I can't get my Demon to work", or "I never had problems with my Holley and no tunning" or how bout " I didn't need to change my jets" graemlins/sad.gif

well im a demon fan...have a 750 mighty on my 350, BUT a 650 holley and a 650 demon are definately 2 different carbs. Demon wet flows theres, while holley dry flows, so really a 650 demon is way more carb than a 650 holley.

Barry Grant doesnt have a good reputation for customer service, or repairs.

My comments were posted based upon my experience with Demon carbs. I'm not saying Demon carbs are junk, not that I wasn't able to tune them in the end. I only stated that the Holley carbs (again in my experience) are easier to tune and are generally calibrated pretty well right out of the box assuming you didn't order or get sold the wrong carb for your application.

As for me not having to tune my carburetor, where did you read that :confused: I've spent 10s of hours dialing in my Holley HP 950 for max performance, testing different jetting, pump cams, squirters and screws, plugs, PVs, spacers and on and on and on. Having said that I can tell you after having done all this testing I'm not far away from the original carb calibration (slightly more jetting, blocked rear PV and bigger squirters). And even in box stock shape my HP 950 never caused my car to run like do-do. I doubt I've recognized more than .05 in ET with ALL the carb tuning I've done.

Maybe I don't know how to tune a carb as well as you do :rolleyes:

I'm clearly in the minority hear. Ya'll enjoy your Demon carbs and happy motoring.

Kjett its all good man maybe I can tune a carburetor better than you or maybe I can't thats not the issue its bout being reasonable and given valuable information to others. You have given valuable information in your last statement that someone can use rather then "I had several Demon and could not get them to work and if you had a Holley it would happen" If you stay in hot Rod, muscle cars or performance in general you will see some peoples preferences in carburetor, ignition, and other performance parts we just hope they make sense and reason when they argue points.

I am already having fun with my Demon in my little small block! :cool:

Go with the Edelbrock 1407 manual choke 750 CFM......... :D Sorry man, couldn't resist!!! Next up, Quadrajet lovers, no doubt!!!!

go webers they look cool graemlins/beers.gif . look at it this way . if you want a demon we are not going to stop you. but let us know how you make out and how much your selling it for. :D j/k

Originally posted by Steves71:
Holleys are way hard to tune.
:rolleyes:

mighty 650.....will be here friday morning
shane

Originally posted by Spawn22:
Here is my 0.02 cents!

... The Engine was chassis
Dyno at 410 Hp flywheel and 448 lbs of torque ... How do you chassis dyno a car for flywheel power?

Was not on a chassis Dyno but a engine dyno, I will have it chassis dyno next month here in Sacramento at this place. SVS (http://svsrnd.com)

Brian, yeah the tech guys at demon are idiots, ill be the first to agree. They didnt answer 1 question i had. All they kept telling me was "no sir we do not recommend this and that and yada yada yada" but that dosent mean the carbs are no good. I couldnt spend more money on an HP holley and get less quality parts. It may run good out of the box but you know what that tells me, its not a touchy carb and will be very "general" thats all.

Oh and i was going to vote for a "6- stromburg" setup graemlins/clonk.gif