Speed Demon 650 frustrations!

Ok this might be a long one, depends how pissed i still am by the end of it. :Zip2: I just picked up a speed demon 650 (it was the remanufactured one). I took it apart and cleaned it up cuz i've heard about all the metal flakes floating around (see i've done my homework!) and put it on the car. Talk about a car part looking sexy though! The damn thing looks awesome, i just wish it worked as well as it looked. First of all the idle eze thing doesn't work at all. The tech guys said that my cam would have to be bigger for it to work. I've got a blue racer (.472/.496 214/224 @.50) and its a pretty lumpy cam for the 289. Anyways, the idle sucks, it seems to be running VERY (70's primary 78's secondary) rich and if i back the secondaries AND the primaries all the way out, the car will still run. With a holley it would die in a second. The tech guys at barry grant told me over and over again "This isn't a holley".....well why the hell does it look like one then? :shrug: The thing that concerns me and i guess this is my big question/poll to others who have demons......when i try to shut my secondaries all the way down, i can see light through some of the edges, almost as though they aren't seating properly. To me, this is why the car still runs when they are shut, because they really aren't shut! Has anyone else noticed this? I have a proform billet baseplate that i was using for my holley 650, should i switch the two?? The proform one seems to be of high quality, and i THOUGHT the demon would too! Who knows, maybe 7 years of tuning holleys has brought me all the way to square 1 with demons. I'll look on amazon for a tuning book. Sorry for the length (funny, never had to say that before.....:rolleyes: ) HAAAAAA! Thanks guys!
 
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I tuned it just like the holley. A 70 primary to me seems a little high. I run a 72 primary for the supercharger 650 holley carb. Maybe I'm running lean though. I run a 68 or 67 primary without boost. If you are close to sea level you might be okay with 70s though. I don't have an idle ease base so don't know. My butterflies seat tightly. I just rebuilt the carb and bench tuned it and remember checking for that. I have three Demons, but only opened up two. Both so far had aluminum shavings. I have regularly had to remove shavings from the needle and seat.
 
Idle has nothing to do with the main jets. When you say you Back the mixture screws out, that should make the system run richer not leaner!

Anyways. the carb's are very good, and tuner friendly jsut need to have some patience and understand the basics with it. First of all, make sure your butterflies are set correctly. see if you can lean the thing out, with the mixture screws, enough to get a good clean idle and non power run up to 3000rpms. If the screws are turned nearly all the way in (closed) then you need to do some reading. The idle circuit is too rich and needs some attention, either by the Airbleeds, or Idle feed restrictor.

Yes that cam is small even for a 289. When they talk about big cams they are speakin of ones with 550 lift and 280 plus durations! Good luck. There are some very good articles out there about how to tune carbs. We can guestimate and give advise over forums but you truly need to understand how it works, before just changing jets etc...

I personally own a road demon 625 vac secondary, it is a good carb when tuned properly, out of the box it sucked! took many hours of reading and understand what the problems before I could touch the carb.

My new carb is a QuickFuel unit were everything is swapable, now i paid a premium for it, but I want that tunablity without using wires and epoxy etc. Most entry level carb require the wire/epoxy treatment for precise tunes, EVEN HOLLEY. (other then the Ultra HP series)

the proform main body is great, but won't help you with your problem!

As for your secondary butterfly fit, it is more the position of it rather then the exact fit of it(sure a better fit would be nice, but not the problem at this stage) it is the exposing the idle circuit that has the biggest effect to the idle circuit.
 
Hey thanks for the replies, i'll take all that into consideration. Guess i'll hit up amazon for a good book on demons.....suggest any?? The proform part i was asking about wasn't a main body, it was a throttle baseplate. It has the same 1 11/16 throttle bores (im pretty sure) and it is supposed to fit a holley 650. The only thing it wouldn't have would be the idle eze but that thing isn't working cuz my cam is too small. Lemme know whatcha think! Thanks again!
 
demons are notorious for running rich right ou of the box. tuning it is very similar to tuning a holley but it's not exactly the same. mine is a 625 road demon and it runs rich as well. i haven't taken mine apart yet but it will happen this spring. i'm almost positive that the pv is too big for my app. i have the same cam as you basically but it's a speed pro not a blue racer but the specs you posted are the same as mine, mine has a 114* LSA
 
I have a 650 speed demon, runs awesome, but slightly rich at idle. First thing, if you lower the float level so it is even with the lower edge of the sight glass, it'll reduce some of that rich at idle condition. Also some Demon experts have suggested initial timing as high as 18-20 degrees to also help this condition. I run mine at 18 degrees initial, 36 total.
 
yeah i've backed the screw out all the way on the secondaries (so they are shut all the way) and still a tiny bit of the transfer slot is showing on the bottom. That was why i was wondering if i could use my billet proform baseplate that i had on my holley in place of the demon one. It just doesn't look like the butterflies are seated perfectly in the throttle bores....who knows maybe they don't have to be perfect. Does anyone know if you could use a holley baseplate on a demon? I'll try the float level thing, mine sits right in the middle of the sight glass. I have a 67 primary and a 73 secondary in my old holley, does this sound about right? Should i switch out the 70 and 78's that are in there now for the 67 and 73's?? Thanks again for the time you guys have put into this!
 
Again, you aren't gonna fix the rich idle by changing jets.

The float levels will though. That being said, demons have larger Dominator style bowls. They need to be in the mid of the site glass, unlike the holley which get set to the bottom of the hole. But lowering them does help for many People.

This again is a stop gap fix, and your idle circuit NEEDS attention.

As for the plate thing, are you saying your plates are off centered? or they are undersided completely?

Using the Proform on the demon works, but the demon base is the same darn thing, I'd say before swapping out the entire base, see if you can just change the butterfly plates.

Good luck, let us know.
 
Oh yeah i totally understand what you mean about the idle, what i meant by the jet size is that when giving it some gas (up to 3500 rpm to check my total timing) the engine bogs down and shuts off after i let off of the gas. Im thinking that its loading up with too much gas and getting bogged down. I took the carb off and there was gas pooling on the intake. Thats why im thinking it was too rich. I'll have to play with the idle circuit also. I had gotten the idle just to where if i leaned any of the circuits (4 corner idle) out any further, the rpm would start dropping. Also i already have the proform base, its not like i would be buying it and then trying it out. It looks as though the butterflies just aren't seated right, i can see light around some of the edges when it is fully shut. You'd think for a $400 + carb they'd have these things worked out. For $400 they better include a guy in the box to install and tune it. Thanks again for the suggestions!
 
ok well i tried a few more things and then took the car for a spin. I went back to the jets that were in my original holley 4150 (650 double pumper) which were 67's primary and 73's secondary. The power difference is noticeable. I think the main body of the demon is a great design and looks awsome, im questioning the baseplate and possibly the metering blocks. I also have that bog problem. Its hard trying to figure out what is a lean bog, and what is a rich bog! Right now i have #31 squirters on there and i have that little bog right off of idle. A guy at a speed shop who knows lots about carbs told me to try to mess around with the position of the secondary and primary throttle blade positions. If one is showing too much of the transfer slot and the other not enough, that can make a bog at idle. I think im going to try the proform baseplate off of my holley. Did you guys notice a number stamped on the bottom of the butterflies? My demon says 169 and my proforms say 172......is this a size of some sort? I think with some tuning and possibly getting creative with making a frankenstein carburetor (mixture of demon, proform, and holley parts) i could come up with something pretty powerful. I'll try again tomorrow.....thanks for all the input! Wootdog, im not quite sure what you said there, i still have the demon baseplate on there, but i was thinking of switching to the proform one. They are the same design but it looks as though the proform one is better.
 
Turn the idle screws all the way. Do not over tighten. Back 'em out a turn to start. The backs being open a little bit doesn't matter. It can cause a lean spot, but the idle screws can fix that. I wouldn't mess with the carb. I'm sure it's fine.
A lean bog just falls on it's face. A rich bog usually leaps forward for a sec, then bogs.
 
the holley was looking tired! Plus, i like to wonder, but i'd rather know.....everyone says their carb is better or that one is worse and i think the demon looks great too. I picked it up from a guy on ebay who bought it then realized it was too big for his car. $290 for a $450 carb. I'm going to play around with it some more today and i'll let you guys know how the proform base works on it. I'll get this car running right if i have to sit there and pour the gas into the intake myself.....self carburetion!
 
Did you follow the directions to pre-set the butterflys?

Did you follow the mixture and air bleed pre-sets?

I did and when I bolted it on, it fired right up. Set the idle and some minor mixture adjustments and it ran like a top.