Holley/Demon Carb stumble
- Thread starter Cudafever
- Start date
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What if i just raised the float bowl on the secondarys..........Would make the fuel start to pull thru the venuri quicker....?
I know this is not right and will affect the hole calibration of the Seconday side
Better ideas to try first!.......But that has been rattaling in the back on my brain this morning......
I know this is not right and will affect the hole calibration of the Seconday side
Better ideas to try first!.......But that has been rattaling in the back on my brain this morning......
Somethng like this
Three to keep in mind.
As the air flow past the booster begins to increase,
1. Fuel in the air well or tube goes somewhere. It goes toward the booster.
2. Air coming through the upper bleeds is blowing at high velocity which pushes fluid toward the booster.
3. The air bled in reduces the density in the main well, so the fluid moves quicker.
Three to keep in mind.
As the air flow past the booster begins to increase,
1. Fuel in the air well or tube goes somewhere. It goes toward the booster.
2. Air coming through the upper bleeds is blowing at high velocity which pushes fluid toward the booster.
3. The air bled in reduces the density in the main well, so the fluid moves quicker.
It might. And I have not experimented enough with fuel level to make any gneralization about what it effects more or whether its across the board.
yellow rose
Overnight Sensation
My bad...the thread got long and I thought this was a street/strip car. So yeah, look at vacuum while foot braking.
I was doing some research on line and so guy named Lars
had a article on basic set up on a Speed Demon Carb
He said that the Demon had 3 lines on the sight glass and that for street you should set it to the lower line............
Does that mean the upper line is is for Race?????????
He didn't say that but I *** um ING
And got me thinking about a higher fuel level.
Wanted to send the link for the article, but can't find it now.
had a article on basic set up on a Speed Demon Carb
He said that the Demon had 3 lines on the sight glass and that for street you should set it to the lower line............
Does that mean the upper line is is for Race?????????
He didn't say that but I *** um ING
And got me thinking about a higher fuel level.
Wanted to send the link for the article, but can't find it now.
K about to go do some experimenting.
First of let get up to date.
This is my Mighty Demon Carburetor. All the part i put on this one to fix the problem i ended up with another carb. and was able to put this one back together.
Tell me what you think of the video. i was able to get closer and a better, Clearer video of the carb/fuel flow
after the slow mo,(EDIT: the slo mo is in high gear) all the rest are with it in high gear, foot on the brake.
2nd video is only me raising RPM up to what i'm at staged and ready to good and what vac the eng has at that point.
With all that, look at it and tell me what you think
Woop!
I uploaded the UN edited version.
O well here you go.
This is my Mighty Demon Carburetor. All the part i put on this one to fix the problem i ended up with another carb. and was able to put this one back together.
Tell me what you think of the video. i was able to get closer and a better, Clearer video of the carb/fuel flow
after the slow mo,(EDIT: the slo mo is in high gear) all the rest are with it in high gear, foot on the brake.
2nd video is only me raising RPM up to what i'm at staged and ready to good and what vac the eng has at that point.
With all that, look at it and tell me what you think
Woop!
I uploaded the UN edited version.
O well here you go.
Last edited:
Look at that ! the 2:30 slow mo shows it. No fuel flow at the boosters = bog
Reduce the HSB 2 sizes and try it again
(qualifier: that 850 is probably too big and signal drops to nearly nothing.. exasperating the isssue)
Reduce the HSB 2 sizes and try it again
(qualifier: that 850 is probably too big and signal drops to nearly nothing.. exasperating the isssue)
j par
Well-hung Member
I think it's obvious the left side immersion inaugurater was causing an interruption in the right side re pump regulator.. I think that's obvious in the video at the 4:20 mark... Just my humble opinion....
Thought i would give you all a day to tell me what you saw before i went and did the same.
First off....Yup, like has been said and implied all threw this thread, the Speed Demon 850 is JUST TO BIG!
And watching the booster trying to draw fuel and only being able to dribble is "dead truth!"
But this is what i notices beside from the bad Shake, dim lit video.
At the beginning of this thread when i keep throwing bigger squirted in it to fix the bog and every on said Put A 50cc pump in it. I never could decide if i should put it in the primary side or the secondary side.!? Well that video showed the primary side squirt er die out much sooner then the secondary.
NOTE: 50 cc on primary side.
I noticed that the left/drivers side Rear Venturi would dribble a little when i open up the secondary, manual.
In the slow mo video, even when the mains came on, they were more drippy then spraying.
Primary never did more then drip.
Why does it bog/act up, MORE when it warm then when i have run it for a while at eng temp??????
MY Answer: when the fuel come out of the mains in a dribble,(droplets) the bottom of the manifold is hot enough to put it into suspension...or more of the droplet into vapor.
My Cruise rpm is steady state around 12" of vac and 9 under slight acceleration.
My staging rpm is around 9" and i have a 6.5 PV in it right now.
Would replacing my 6.5 for 10.5 PV help????? Probably but not enough. The full throttle dribble would still be the same as we r at (0) vac at that point.
As far is the o2 meter. that is as much live data so far.
that was from about 20 mph in 3d gear 4000 stall up to 5000 rpm.
Ran out of road to go to 5800 rpm
Like the fact that it leaned down to around 12.6 then when back up to 13.5 and look like it was going to hold around there.
Note: only full throttle, is accurate numbers as the sensor is a foot from the exit of the exhaust
Whats next?
Well i want a ET slip with a good mph from this carburetor, then pull it off and start to figure out why the Proform don't pull as well on the top.............or that my butt odometer is incorrect and there is no different in the top rpm/ HP between carburetors.(same day same air)
Was going to have a T@T this week end but Mother Nature say NO!!!!
First off....Yup, like has been said and implied all threw this thread, the Speed Demon 850 is JUST TO BIG!
And watching the booster trying to draw fuel and only being able to dribble is "dead truth!"
But this is what i notices beside from the bad Shake, dim lit video.
At the beginning of this thread when i keep throwing bigger squirted in it to fix the bog and every on said Put A 50cc pump in it. I never could decide if i should put it in the primary side or the secondary side.!? Well that video showed the primary side squirt er die out much sooner then the secondary.
NOTE: 50 cc on primary side.
I noticed that the left/drivers side Rear Venturi would dribble a little when i open up the secondary, manual.
In the slow mo video, even when the mains came on, they were more drippy then spraying.
Primary never did more then drip.
Why does it bog/act up, MORE when it warm then when i have run it for a while at eng temp??????
MY Answer: when the fuel come out of the mains in a dribble,(droplets) the bottom of the manifold is hot enough to put it into suspension...or more of the droplet into vapor.
My Cruise rpm is steady state around 12" of vac and 9 under slight acceleration.
My staging rpm is around 9" and i have a 6.5 PV in it right now.
Would replacing my 6.5 for 10.5 PV help????? Probably but not enough. The full throttle dribble would still be the same as we r at (0) vac at that point.
As far is the o2 meter. that is as much live data so far.
that was from about 20 mph in 3d gear 4000 stall up to 5000 rpm.
Ran out of road to go to 5800 rpm
Like the fact that it leaned down to around 12.6 then when back up to 13.5 and look like it was going to hold around there.
Note: only full throttle, is accurate numbers as the sensor is a foot from the exit of the exhaust
Whats next?
Well i want a ET slip with a good mph from this carburetor, then pull it off and start to figure out why the Proform don't pull as well on the top.............or that my butt odometer is incorrect and there is no different in the top rpm/ HP between carburetors.(same day same air)
Was going to have a T@T this week end but Mother Nature say NO!!!!
Yeah, that dribble had me concerned too. I'm sure Demons have stepped boosters, right? right? I mean, they have to, right?
I wouldn't spend my hard earned cash on a carb without stepped boosters.. they're the best thing since practice trees.
Cudafever, can you verify?
I wouldn't spend my hard earned cash on a carb without stepped boosters.. they're the best thing since practice trees.
Cudafever, can you verify?
I have heard of annular and step down not stepped
if it was a step down booster You could see it in the video booster are necked down further down into the bore.
I had soo so many pictures of this demon carb.....when by by when i got laid off because it was a company phone. and well i don't have access to them any more
if it was a step down booster You could see it in the video booster are necked down further down into the bore.
I had soo so many pictures of this demon carb.....when by by when i got laid off because it was a company phone. and well i don't have access to them any more
Ok, I figured it HAD to.
You know, I just had a stupid simple test to try... Disconnect the secondaries. If you still have a transition issue, well, you have a transition issue. lol
If it blasts out and gets up on the tire, the carb is too big.
Now, when you get your new job NEXT WEEK you may be closer to sea level and this won't be such a problem.
You know, I just had a stupid simple test to try... Disconnect the secondaries. If you still have a transition issue, well, you have a transition issue. lol
If it blasts out and gets up on the tire, the carb is too big.
Now, when you get your new job NEXT WEEK
you may be closer to sea level and this won't be such a problem. Wife is wanting to move to UTAH close to the kids. Aka 4400 feet, instead of 6600 feet.............Only real big problem is the RMR raceway closed 2 year a go. now.........closes drag strip is Hypoxia aka 6600 feet
Boise, long drive 3xxx feet or Denver...5xxx foot elevation. I'm going to mis this place. Was/is only 5 miles for the track
Boise, long drive 3xxx feet or Denver...5xxx foot elevation. I'm going to mis this place. Was/is only 5 miles for the track
BTW, those stepped boosters were designed to 'bust' the fuel up into a finer particle.
The 'step' creates a low pressure area that the fuel is happy to fill the entire 360° of the step, once it does, it shears into the air stream in the form of smaller droplets.
Beings that you're not experiencing this 'busting of fuel', it offers proof of a carb being too large. There's simply not enough velocity maintained for it to function properly.
I know you've been kinda beat over the head with this... I'm sorry.
The 'step' creates a low pressure area that the fuel is happy to fill the entire 360° of the step, once it does, it shears into the air stream in the form of smaller droplets.
Beings that you're not experiencing this 'busting of fuel', it offers proof of a carb being too large. There's simply not enough velocity maintained for it to function properly.
I know you've been kinda beat over the head with this... I'm sorry.
Been around sence the 60" i started racing three in the early 80"
End of an era: After 50 years of racing, Rocky Mountain Raceways grabs the checkered flag
End of an era: After 50 years of racing, Rocky Mountain Raceways grabs the checkered flag
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