Carb Choice

[Taylorman]

Im researching the best carb for a BBC in the 500 hp range. Im looking hard at Demons. Im looking at the Mighty Demon 850 cfm.
Whats the difference between downleg and annular boosters.
Any thoughts on carbs are welcome.

[1978 Rogers]

Why not just a typical Marine Holley? Just curious.

[Taylorman]

I see they make a Dominator in a 750. Whats the advantage of using a 750 dominator vs a 750 4150 carb?

[flat broke]

for the price of that 750 Dominator you can run a mighty demon which also has the screw in bleeds, smooth entry top, etc, and come out $$ ahead. I like the Demons I have on my boat, buuuuut they are a bit of a pain in the arse to get the idle set correctly on. The newer ones have that "idle ease" dealio which basically allows air to enter the plenum through the breather stud hole and an adjustable needle/seat type arrangement, and I would think this would allow you to close the trottle blades to where they should be and still get enough air in the carb, but I'm not utilizing the option on my carbs.
As far as the annular booster vs the downleg, the annulars "should" provide better throttle response. When we dyno'd my motor we noticed some very "interesting" things about changing the angle of entry for air above the booster and its result in signal etc. The annular booster was very sensitive to what was above the air horn on the carb and you could see the mixture change with something on the horn vs. nothing on the air horn.
Bottom line, IMHO the mighty demon carbs are a good bang for the buck in terms of available tunability right out of the box without additional machining, at a lower price than the Holley HP series carbs.
Chris

[Taylorman]

The mighty demon is the carb i will most likely buy, probably an 850 for the 454 i will be building. Looks like a pretty good carb for $500. Thanks for the info on boosters.
What does IMHO mean?

[HalletDave]

.What does IMHO mean?
IMHO = In my honest opinion. I think. :D

[oldbuck40]

Hey Remember Who I Told You To Call And What Your Looking For Is The ,,,speed Demon #dem 1563010 850 Double Pump @$439.99 The Jet Sizes Are Front 85 Rear 93 And Its Plenty For My 496 Bbc,,and They Will Bolt On And Crank With Minimal Adjustment,,,i Have The Spec Sheet On This Carb If You Want It,,,just Say The Word

[Jake W]

I would not use ant thing other than mecanical secondaries on the Dps.I bought a Carb from Bigs Preformance.It is very responsive and never missed a beat.I just sent it back in to have it set up for the changes I made to the motor and to have it recolored and crome bowls put on.These guys make a very nice Holley DP 750 850 dominator what ever you want.They can help you out.
Bigs Preformance# 715 835 3726
Jake

[Hotcrusader76]

If you're going to buy Demon than look no less than the 825 Mighty Demon. The Speed Demons are junk and far from being 'easily' adjustable. You want to buy the Annular boostered version considering your CID and predicted HP. If you go with vacuum secondary than get the 850 version otherwise the mech.secondary 825 (Annular booster) is the way to go.
For some reason Demon went to shit on the Speed Demons and less. When comparing quality to quality....the HP Holley and Mighty Demon are neck in neck, not to mention that the Mighty Demon 750 has a much larger venturi than the 750s, despite the CFM rating. Very misleading if you ask me.
Four corner idle will keep any motor's temp better balanced and provide a killer off-idle response over the two-corner version. I add this modification to all of our carburetors because most motors today, including the crate versions really need this in order to idle smoothely. The mighty Demons comes with this, some Speed Demons don't. Beware~
~Ty