demon carb - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 08-26-2003, 11:51 AM
lilbandit3's Avatar
New Member
 
Join Date: Jul 2003
Posts: 17
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
demon carb

I have a 400 Pontiac, 4X heads, edlebrock torquer2 intake, headers, custom exhaust. I am lookin at somethin about 800 cfm with mechanical secondaries. probably speed demon or might demon. which would give me most preformance? Just want to hear from you guys before i buy anything.

thanks

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 08-26-2003, 12:09 PM
NDA Racer's Avatar
New Member
 
Join Date: Aug 2003
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The regular ol' Holley double pumper will perform just as good (at the track). Unless you want the looks of the Demon, or just the sake of having one.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-26-2003, 12:40 PM
Member
 
Join Date: Jan 2003
Location: greener pastures
Posts: 238
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
DEMON carburetors run rich, very rich from the box...and they will require some tinkering abilities to get them adjusted correctly. If you're not up to the task, I'd stay with something like the EDLEBROCK which is basically a take from the box, adjust the idle mixture screws and enjoy it carburetor. It'll give you decent street performance, good economy and is user friendly. It like most carburetors will require a fuel pressure regulator and a gauge to insure correct fuel pressure.
If you like to tinker, then the HOLLEY or DEMON are for you.
I currently am waiting for BARRY GRANT tech support to get back to me with suggestions on how to get my DEMON to quit belching eye burning, plug fouling, oil diluting exhaust. It's been a six week project with the carburetor. When and if I can get it adjusted, it should perform great and you can't beat the looks of it, but...
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 08-26-2003, 01:26 PM
gt2betubbed's Avatar
Kid With A Wrench...
 

Last journal entry: The Blower and test fit.
Last photo:
Join Date: May 2003
Location: Cali Baby!
Age: 35
Posts: 1,106
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hotwheels, keep with it because like you said, once you get it dialed in, it'll perform GREAT!.

Lilbandit, I think you should take a step down on the carb. 800cfm may be a little too big for your motor, and it would cause even more headaches while tuning. The looks of a Demon is more than enough for me to get one, but it is true with tuning of it (my bro's 750 still isn't right).
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 08-26-2003, 08:12 PM
New Member
 
Join Date: Aug 2003
Posts: 23
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ok, I am repling to the guy that has been working on the demon for weeks. Do not know what steps you have been going through, and do not know what kind of motor but if you give me your engine specs, maybe I can help.

First make sure you have about 12 degrees of initial timing. Turn all mixture screws to 1 turn and get the car to Idle. When car is at idle turn all 4 mixture screws in 1/8 of a turn. If motor idles up, set idle speed back to rpm in which you want to idle. Turn all 4 mixture screws in another 1/8 of a turn. Do this until idle starts do go down when you turn in mixture screw. If you can bottom out all four mixture screws and the car still idles to rich drop me a line on this forum and I can tell you where to go from there.

Just tring to help you out but trust me I can talk you through it.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 08-26-2003, 10:04 PM
Member
 
Join Date: Jan 2003
Location: greener pastures
Posts: 238
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks, I've been through all of the suggested steps made by DEMON tech staff and a half dozen others. Still have the problems with my new ROAD DEMON 625 cfm...
When I first contacted their tech staff, I was told I should have purchased their more expensive "calibrated crate motor SPEED DEMON" instead. I felt that was not what I wanted to hear from them.
I didn't know they had such a product available when I purchased the ROAD DEMON. I see no reason why this carburetor can't be adjusted to run at least as clean and crisp as the EDLEBROCK 600 cfm I removed from the motor. From reading their specs on the calibrated crate motor SPEED DEMON, it appears to have many of the same specs, but with even richer jetting in the primary and secondary circuits. It does apparently have the ability to easily change the vacuum pod spring and some other options not available on the ROAD DEMON.
I have a new ZZ4 (.510/.474 & .221/.208 @ .050) motor, MSD Pro Billet ignition, Sanderson QP1000 headers, Tremac 5 speed, ignition is set at 12 degrees BTDC as recommended and using ported vacuum. I've tried the manifold vacuum source and it ran worse. I am using a 4" tall K&N filter in an 8x11" oval filter, so the vents are not blocked and it gets plenty of air.
I initially took the carburetor apart as suggested to verify their float settings. I checked for machining flashing that apparently has been found in some of the DEMON carburetors. I checked for vacuum leaks and none were found. Keep in mind that this fresh setup had an EDLEBROCK #1406 600cfm carburetor on it and it ran fine. I've reduced primary jetting from 70 to 68, replaced the power valve with another 6.5 even though it checked fine, and replaced the secondary jetting from 78 to 76. All gaskets have been replaced, including the base gasket and base gasket to main body. I removed the choke to eliminate that from the equation. I intend to replace it if I can get the rich idle resolved. I have completely closed off the secondary blades from the .020 transition as suggested by the DEMON tech staff. The floats are both set so the fuel level is between the lowest and middle marking on the bowl. The setting is correct for the accelerator pump arm.
All adjustments were made after the motor came up to temperature as suggested.
The initial IMS (all four) setting was out 1 1/2 turns to get it started. Lots of really black smoke, eye burning, plug fouling, fresh oil diluting black exhaust. I turned the IMS (all four) all the way in to a gentle seated position and found that is where the idle is highest, the vacuum is highest at approx. 19" and the black exhaust disappears. This gives me a fairly stable idle at 900 rpms. That would indicate a very rich condition to me and the tech said that to be the case. I can turn the IMS (all four) out to one turn and it reduces the eye burning exhaust, but I hear an occasional very slight pop in the carburetor when the rpms are brought up from idle. That would indicate a lean condition, but if I adjust the IMS (all four) out more than one full turn from gently seated, then I get the obvious rich eye burning black exhaust. I've had nothing as serious as a backfire from the carburetor.
I sent DEMON tech staff a detailed e-mail message last Friday and haven't received a response back from them yet.
It was suggested by some people on another site that the air bleeds need to be changed. I believe the air bleeds on a ROAD DEMON are fixed and the idea of epoxying them closed and drilling them doesn't sound like something I should have to do with a new carburetor.
Any ideas Cobra 28? Thanks in advance.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 08-27-2003, 12:50 AM
4 Jaw Chuck's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Mar 2002
Location: Manitoba, Canada
Age: 46
Posts: 4,977
Wiki Edits: 0

Thanks: 2
Thanked 89 Times in 72 Posts
Hot wheels55, have you tried opening the secondaries up more than 0.020"? It would solve your rich idle with additional air, maybe even try 0.010". Since your idle screws are obviously functioning but very touchy and only turned out 1/2-3/4 of a turn to get it to run, it sounds to me like you need the secondaries open more. It's what I do to Holleys, lots of things to adjust. How about accelerator pump clearance, you need a couple thousandths clearance minimum or the pump can dribble.

The reason why this works is because the primary is open too far and is getting into the transition circuit for the primary jets, opening the secondaries reduces the throttle blade angle on the primary and puts it more on the "slot". Sorry if this doesn't apply to your carb but it certainly applies to Holley's, I've never played with the Demon carbs.

Hope it helps.
__________________
Outlawed tunes from outlawed pipes
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 08-27-2003, 07:49 AM
New Member
 
Join Date: Aug 2003
Posts: 23
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ok sounds to me like you have a rich problem. I need one thing cleared up though, you said all IMS in, and black smoke disappeared. Then you said you backed them out to one turn to cure the eye burning exhaust. Did the rich smoke and the burning eye exhaust not go hand in hand?


One thing you need to check is your primary Trans. slot position, because if all your IMS were bottomed out then it had to be getting Idle fuel from somewhere and that somewhere is the trans. slot (only other place it can be coming from). Give me a rough estimate and if I think it is good, we can go from there. Keeping it simple for now so we do not get to many things going at once.

o yea by the way is this a new Road demon, how long have you had it? Did it come with a line kit or did it come with a transfere tube already attached. (just tring to figure out which rendition it is).
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 08-27-2003, 09:12 AM
NDA Racer's Avatar
New Member
 
Join Date: Aug 2003
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
When I first contacted their tech staff, I was told I should have purchased their more expensive "calibrated crate motor SPEED DEMON" instead. I felt that was not what I wanted to hear from them.
Sounds familier. I know a guy that took off his regular ol' 750 Holley dp on his mid 10 sec 406 and put on a 750 Race Demon and dropped into the 11s. After a ton of tuning it and getting close but not matching his original ETs (let alone surpassing it like he thought he should with the "superior carb" ) he called the Tech Support and they told him he needed the 850 Speed Demon (seems they like to sell that carb). Bought the Speed Demon and still couldn't beat the ol' 7fiddy Holley.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 08-27-2003, 09:54 AM
johnsongrass1's Avatar
Race it, Don't rice it!
 
Last photo:
Join Date: Jul 2002
Location: Columbia, Mo
Age: 38
Posts: 4,080
Wiki Edits: 0

Thanks: 0
Thanked 10 Times in 10 Posts
[QUOTE]When I first contacted their tech staff, I was told I should have purchased their more expensive "calibrated crate motor SPEED DEMON" instead. I felt that was not what I wanted to hear from them.[/QUOT]

I will never buy antything that's calibrated for "my specific needs". How the hell can they know what my specific needs are? I understand they have beeen doing carbs longer than I, with more money to spend on research but that will only will give them a good idea. I just hate that marketing plea.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 08-27-2003, 10:02 AM
Member
 
Join Date: Feb 2003
Location: Enumclaw WA
Age: 29
Posts: 61
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
have any of you guys thought about a q-jet ?
also lilbandit3 check out
classical pontiac
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 08-27-2003, 11:38 AM
Member
 
Join Date: Jan 2003
Location: greener pastures
Posts: 238
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I first want to say thanks to all that have responded and I am very sorry that this post turned towards my problems with my DEMON and taking away from the original members post. Hopefully, this will help that member see what he may be facing with his carburetor choice.

to 4JawChuck,
It was my understanding that opening up the secondary transition slot more than the recommended initial starting point of .020 was not ideal...the DEMON tech staff suggested closing it off entirely to aid in leaning the carburetor out. I did try it in increments down to completely closed off and it still ran rich. It is currently completely closed off with none of the transition slot showing. The tech staff said that should allow me to open the IMS more by doing so. The accelerator pump clearance was checked and verified when I first go the carburetor.

I agree with the comments about buying something "calibrated" just for my ZZ4 application. In fact, I asked specifically if that carburetor would just bolt on and be ready to go and I was told no, that all of the DEMON carburetors will need to be adjusted, so I felt I would still be in the same situation regardless. The "calibrated" designation doesn't seem fitting since there are so many variables for each application of the same ZZ4 motor.

to Cobra28,
My post was long and I didn't really review it, so let me clarify that point. With the IMS screwed gently all the way in, the black exhaust disappeared and I achieved the highest vacuum and highest idle using a vacuum gauge and my tach. There was a lean pop indication in the carburetor with it adjusted all the way in, however.
If I screw the IMS out to just one full turn, I get a lower rpm idle, lower vacuum reading, but the black eye burning exhaust disappears. There is still a lean pop condition in the carburetor, but not as frequent, so I think that would indicate I am closer to correct air/fuel mixture.
If I open the IMS out more than one full turn, then I get the black exhaust. Eye burning black exhaust do go hand in hand.
So I am limited to either one full turn out and no more to all the way in for now. It idles fine with one full turn out, black eye burning exhaust is gone, but according to DEMON the one full turn out is not optimal. It needs to be adjusted out more than one full turn according to the manual I received with the carburetor and that aftermarket tech manual that is just for the DEMON carburetors. I think it may be optimal for my application. I think their recommendations were something like 2 or 2 1/2 turns out was optimal and anything less indicates a rich idle circuit.
The only problem I experiance with just one full turn out is that there will be an infrequent light pop from the carburetor when I raise the rpm level at idle.
I don't know what the primary transition slot is set at currently, but the idle is right at 900 rpms with the IMS out just one full turn.
This is a new ROAD DEMON 625 cfm that I bought in the box from a NM distributor of DEMON carburetors. I purchased it about 6 weeks ago. Mine came with the chrome cheapie fuel line kit and no transfer tube, so I believe it to be the newer model.
Again thanks to all...I'm STILL waiting for the DEMON tech staff to answer my e-mail message that I sent last Friday.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 08-27-2003, 11:57 AM
NDA Racer's Avatar
New Member
 
Join Date: Aug 2003
Posts: 11
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
I will never buy antything that's calibrated for "my specific needs". How the hell can they know what my specific needs are? I understand they have beeen doing carbs longer than I, with more money to spend on research but that will only will give them a good idea. I just hate that marketing plea.
My buddies brother sent his 3310 Holley to the "Carburator shop" to have it dialed in cause he didn't want to wait for the next time my buddy made the 600 mile trip to visit him and set up his carb. The carburator shop asked all the specs of his car so they could supposedly set it up. The car didn't run as strong as he expected once he put the carb on (was a dog). My buddy told him he would check it out when he got there. The jetting was way off, they had the black spring in the secondary diaphram and the check ball was still there too. His brother couldn't believe the difference after he was done. So he flushed a couple hundred bucks to get his new carb "dialed in" by them.

And yes I have run Q-jets and loved them. The ones with the divorced choke that didn't have all the smog fittings. I have run Carters and their brother the Edlebrock they have all treated me well. But for Drag Racing the Holley double pumper is the only way to go in IMO. Just by going with the DP with no other changes other than the carb change (both carbs were the same cfm too) I have dropped 3 10ths off my ET.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 08-27-2003, 12:49 PM
cool rockin daddy's Avatar
1.21 giga-watts???!!!!
 
Join Date: Aug 2003
Location: wherever cool cars are
Posts: 1,535
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
Cool

Hotwheels,

Go back and review your tuning tape that came with your carb. The guy on the tape will say (paraphrasing here) that most Demons will need 1-2 1/2 turns on the IMS to idle correctly. He also says that if your car is idling smoothly, has no off-idle stumble, exhaust is clean at something less than 1 turn out on the IMS that is FINE.

I just got my new Demon carb and in the next day or so I am going to be trying to dial it in and I am hoping I will not encounter the problems that you are having. When I talked to Demon tech about adjusting my carb I asked him about all these problems that some people are having. He told me that usually these problems are from too big a carb for the application as the Demon line flows much more than the size in the model number, ie., a 650 Speed Demon flows more closely to 750 cfm.

My feeling is that these carbs are much more fine in their calibration than most people are used to. I have been told by people that use them that they swear they have fuel injection the engine responds so crisply and quickly. Keep the faith and start from square one if you have to. I am sure you will get it sorted. There is also a gentleman by the name of BOB at FOA performance who is on the internet if you type in "tuning Demon carbs". He is a racer, he sells Demons, he tunes Demons, and he will take tech calls and questions no matter where you bought the carb. Good Luck.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 08-27-2003, 01:23 PM
Member
 
Join Date: Jan 2003
Location: greener pastures
Posts: 238
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the words of encouragement...
I'm sure not ready to give up on this thing yet, but if I do, it'll get sold and I'll go back to the dependable EDLEBROCK product line.
I am a firm believer in not over carburating a motor, especially in my case where it is strictly a street cruiser ('57 150 sedan). I had many tell me to use the 750 cfm or the 650 cfm double pumper and I just didn't see the need when a 600 cfm EDLEBROCK worked fine. I WANT THIS DEMON TO WORK FOR ME!
I'll go back and re read the manuals and review the tape again...I could already be as good as I can get it with just one full turn out. I've had it apart so many times, I'm sure I haven't missed anything else.
Thanks again!
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 02:54 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.