Does anyone have an opinion on speed Demon Carbs.
I have a mildly built 340 that made 400HP on the dyno.
My old Holley has finally had it and I just purchased a 750 CFM Speed demon.
I keep hearing horror stories about problems with these carbs. The 1st one I got leaked fuel from every where out of the box. I sent it back, and they sent me a new one. Does anyone have experience with them? Do you have any recommendations on a decent street/strip carb that is reasonably priced with good performance.

I'm running one ( mechanical sec. annular booster 750 ) on my 408. Verdict is still out, as I only have about 10 passes on it. The 4 corner idle circuit seems extremely touchy. I'm only out about 1/2 turn on the mixture screws. More than that and it goes rich. Center air bleed is wide open. Other than that, it seem to work ok. I made multiple changes when I changed carbs ( reads stupid ), so I don't have a good carb comparison.

Mike,

""Do you have any recommendations on a decent street/strip carb that is reasonably priced with good performance.""

I had a 650 DP Speed Demon on my 340 and once I got the chips cleaned out, it ran pretty good. My 4 corners were always around 1/2 turn out and the only reason that I modified it (Proform main body) is because I stripped out a squirter thread. I have learned since that I like a carb with as much adjustability as I can get because I love to tweak. If you can get yours cleaned out, I would suggest that you keep tuning it unless your cam specs are outside of the range for the Speed Demon.

As far as reasonably priced with good performance, you will get what you pay for when it comes to carbs. Everyone has their faithfull brand so what I will suggest is to figure out if you want a mechanical or a vacuum secondary unit, and then shop around for the "bells and whistles" that you like. The more adjustability the more that you will pay. If you stick with the Demon brand, you might want to look at the Mighty Demons since they have replaceable bleeds and the Speed Demons do not. If you like DP's, I would suggest that you look at the Quick Fuel Street Series carbs. Their DP's have adjustable mechanical secondary linkage kits that allow for 1:1, 40% delay, and a 60% delay (Most DP carbs just have the factory secondary linkage with no adjustments). They also have electric chokes, reaplaceable IFR's, IAB's, and HSAB's for the common tuner.
Their are allot of different Demon/Holley style carbs out there so pick your options and then go shopping in your price range.

Sorry, mine is a Mighty Demon 750 - not a speed Demon. Re: the 1/2 turn out on the mixture screws. When I talked to the tech guy at BG, he said to go 3 sizes smaller on the idle feed restrictors - from .036 to .033". When I opened mine up, I found the idle feed restrictors were already at .033. ( new carb out of the box - per their literature - is .036??? ) After the factory "quality control" bells & whistles quit ringing in my head, I checked to see if all else ( jets, air bleeds, PV, etc ) was per the carb literature and all else was as stated. Although my cam duration falls well with in what is suggested for this carb, I have to run it with the "idle-Eze" air bleed wide open and the butterflys open a goodly amount ( boarder line in to the transition slots )to get enough air @ idle.

I would go smaller, the 650 is a beter match and I've found Demons are very touchy to being too large. Like was said, pull the bowls, clean out the chips they left in it, visually inspect the metering plates for machining bits hanging in the passsages, and then you can proceed with tuning it. I typically dont buy Demons any more because of the time spent doing basic cleaning/debugging on them even when new.

I hate to highjack, but what jets do you use if you want/need to change them?

i am running a 750 speed demon on my 408. I love it know but when i first got it out of the box all hell broke lose. Dumping gas in the motor.

I took of one of the bowls as there where metal chips behind the power valve one screw for the float half-way back out.

I sent it back to demon they sent me repaired it for me. " i did pick-up the carb about 3 months before i put it on the motor."

motor runs great i played with the vac. sec. springs runs just as hard as a DP carb IMO.

The choke setting i found to be very sensative.

If i would do it again i would of went with the mighty demon but you do lose the choke which would not too be fun in cold weather.

Demon carbs can be very finicky and a pain to adjust...save your money and get yourself a quick fuel,best carb. i ever bought 850 quick fuel out of the box adjusted idle and has worked flawlessly for 3+ seasons now...