Demon carbs
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Race Director
Joined: Dec 1999
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From: Forked River NJ
Originally Posted by redc3
i have a 850 dp speed demon on a 383 with really lumpy cam. the idle eaze does nothing . im very displeased with this carb
Melting Slicks
Joined: Dec 2004
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From: pr, frederick md.
Originally Posted by Gordonm
Have you gotten any carb to work on this combo? What are your cam specs?
Thread Starter
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From: Forked River NJ
Originally Posted by redc3
havent tried any others yet. ive stated before that this carb has been junk since i took it out of the box. bowls were loose, whatever the fluid is they test with all over the place when i cut open the bag, secondaries would not open, the link arm was jammed. my problem is that i cannot tune out a stutter or bucking when the throttle is going from idle to open and vice versa. and if i try to hold a steady speed it will buck. in other words i have to be in it or out of itfor it to run properly. the idle eaze does nothing in any psition. lars stated it was a timing problem but ive replaced the distributor( for other reasons) and have set the timing correctly. he is not the ONLY dude that can use a timing light and adjust a carb. quite simply this demon carb is junk. as for my cam, its got .525 lift on the intake and exhaust, 307 duration at .006 tappet lift, 110 deg. lobe sep
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From: Clayton NC
Originally Posted by redc3
havent tried any others yet. ive stated before that this carb has been junk since i took it out of the box. bowls were loose, whatever the fluid is they test with all over the place when i cut open the bag, secondaries would not open, the link arm was jammed. my problem is that i cannot tune out a stutter or bucking when the throttle is going from idle to open and vice versa. and if i try to hold a steady speed it will buck. in other words i have to be in it or out of itfor it to run properly. the idle eaze does nothing in any psition. lars stated it was a timing problem but ive replaced the distributor( for other reasons) and have set the timing correctly. he is not the ONLY dude that can use a timing light and adjust a carb. quite simply this demon carb is junk. as for my cam, its got .525 lift on the intake and exhaust, 307 duration at .006 tappet lift, 110 deg. lobe sep
I would think if I got any product as you described I would have asked for a replacement.. However since you have it. It seems everytime I've looked at one that someone has and is displeased this is what I find.. The primary and secondary's are not set the same and not properly so that the air bleed is .020. If you set it to there and set the 4 corners at 3/4 out you should be able to get it to idle well at 850 rpms... BTW the 850 Maybe to big... Maybe not saying it is...Dave
Melting Slicks
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From: pr, frederick md.
ive often thought the 850 was a bit much, but this was recommended to me by my friend and we both build engines. the car runs extremmelly well as long as im getting down on it. its just its cruising manners that cannot be tuned out. it can make one upset when you let off the gas and your car starts to buck so bad your head hits the seat until you give it more gas. im gonna try a smaller carb when the taxes get here. should i still try a demon only smaller?
Drifting
Joined: Jul 2002
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From: Rosemount MN
Just got my engine from the Speed Shop.
383 W/ Comp XR282HR, Speed Demon 750.
It took 9 dyno runs with a primary and secondary jet change each time, before we got the front to rear and A/T ratios right. It was also good for about 45 HP.
If I remember correctly it had 70/75 Primary/Secondary jets stock, we wound up with 88/95.
Get it on a dyno that can measure fuel flow to both primary and seconaries with a good A/F meter.
383 W/ Comp XR282HR, Speed Demon 750.
It took 9 dyno runs with a primary and secondary jet change each time, before we got the front to rear and A/T ratios right. It was also good for about 45 HP.
If I remember correctly it had 70/75 Primary/Secondary jets stock, we wound up with 88/95.
Get it on a dyno that can measure fuel flow to both primary and seconaries with a good A/F meter.
Burning Brakes
Joined: Apr 2004
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From: Des Allemands LA
Originally Posted by redc3
ive often thought the 850 was a bit much, but this was recommended to me by my friend and we both build engines. the car runs extremmelly well as long as im getting down on it. its just its cruising manners that cannot be tuned out. it can make one upset when you let off the gas and your car starts to buck so bad your head hits the seat until you give it more gas. im gonna try a smaller carb when the taxes get here. should i still try a demon only smaller?
Ever thought about down shifting? If the car bucks that bad I would think there is more than just a carb issue. I also think if I spent 400-500 dollars on a carb and it was damaged, I would have sent it back-before trying to get it to work. As far as I'm concerned I'll never own another Holley.
ltlevil
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Instructor
Joined: Dec 2004
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From: Gainesville GA
The Idle-Eze system is only going to be work if your combination needs more air at idle due to a large camshaft. If the engine doesn't require more air it's not going to do anything.
An 850 carburetor would be extremely large on a SBC. The 850 Demon carburetors are not recommended on engines smaller than 480". Running a big carburetor on a small engine is going to cause the engine to be rich at idle, and then since the air velocity is not high enough you will have poor throttle response, and acceleration, and can actually run lean at WOT.
An 850 carburetor would be extremely large on a SBC. The 850 Demon carburetors are not recommended on engines smaller than 480". Running a big carburetor on a small engine is going to cause the engine to be rich at idle, and then since the air velocity is not high enough you will have poor throttle response, and acceleration, and can actually run lean at WOT.
Melting Slicks
Joined: Dec 2004
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From: pr, frederick md.
Originally Posted by ltlevil
Ever thought about down shifting? If the car bucks that bad I would think there is more than just a carb issue. I also think if I spent 400-500 dollars on a carb and it was damaged, I would have sent it back-before trying to get it to work. As far as I'm concerned I'll never own another Holley.
ltlevil
ltlevil
Melting Slicks
Joined: Dec 2004
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From: pr, frederick md.
Originally Posted by Doug S
The Idle-Eze system is only going to be work if your combination needs more air at idle due to a large camshaft. If the engine doesn't require more air it's not going to do anything.
An 850 carburetor would be extremely large on a SBC. The 850 Demon carburetors are not recommended on engines smaller than 480". Running a big carburetor on a small engine is going to cause the engine to be rich at idle, and then since the air velocity is not high enough you will have poor throttle response, and acceleration, and can actually run lean at WOT.
An 850 carburetor would be extremely large on a SBC. The 850 Demon carburetors are not recommended on engines smaller than 480". Running a big carburetor on a small engine is going to cause the engine to be rich at idle, and then since the air velocity is not high enough you will have poor throttle response, and acceleration, and can actually run lean at WOT.
Drifting
Joined: Jul 2002
Posts: 1,943
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From: Rosemount MN
Originally Posted by redc3
an 850 would be EXTREMELLY large on a stock 350. but mine is far from stock. the only part that is not from the aftermarket is the block. while i do agree that it is still SLIGHTLY to large for my 383, with .525 lift cam. all other tuning areas are fine. idle, mixture, ect.... its only when i lift or try to hold a steady speed. whats a typical dyno run cost?
Instructor
Joined: Dec 2004
Posts: 124
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From: Gainesville GA
Originally Posted by redc3
an 850 would be EXTREMELLY large on a stock 350. but mine is far from stock. the only part that is not from the aftermarket is the block. while i do agree that it is still SLIGHTLY to large for my 383, with .525 lift cam. all other tuning areas are fine. idle, mixture, ect.... its only when i lift or try to hold a steady speed. whats a typical dyno run cost?
Safety Car
Joined: Sep 2000
Posts: 4,679
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From: Charles Town WV
Gordon. For what it's worth I'm running a .575 lift .248 duration and the idle-eze really helps. Basically, you'll only benefit if you have a lumpy cam. My demon 750 didn't have the idle-eze, so I retrofitted it with the idle-eze baseplate. It was a hell of a lot cheaper than buying a new carb. There's a guy on ebay who sells them new.
