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  #1  
Old 10-24-2002, 01:26 AM
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timty2 timty2 is offline
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Cry I failed Demon Tuning 101

NOTE: Please refer to my (timty2) last post in this thread for resolution!!!

This post is mainly for Cuda66273, but I would like anyone’s help!

The Problem:
Severe lean misfire

The specs:
Speed Demon 750 Mech. Secondary Order Number 1402010, Jets 76/83, Sq. 31/31. and PV 6.5 (Since changed to 10.5)

The application:
1969 440 Charger R/T, Automatic, 75,000 original miles.

The Story:
After installing Edelbrock Aluminum Heads, Performer Manifold, and TTI headers, (Replacing Stock heads, Holley 750 DP, Dominator manifold, Hooker Headers) we topped the combo off with a Demon Carb. After much head scratching (and inserting the idle air bleeds as instructed by the carb manual for idle problems), I found Cuda's tips on the board very enlightening! Ordered the 10.5 PV (Engine in/hg = 13 at idle/in gear), installed it, removed the air bleeds, and headed to the garage with the 4 corner idle instructions in hand.

I have this baby idling great! Too bad I get it out of the driveway! Big-time bog (Best case) or POP or stall when it's in gear and just trying to get the beast up the street.

With the performance potential of the Demon carb series, this is extremely frustrating! When I gradually open the throttle and hold it at a mere 1200-RPM in park, it leans out and looses RPM; acting like it is starving for fuel. The on-board A/F monitor goes lean off the scale. The bowls are not running out of gas, so that’s not it. Fuel level is set 1/3 high in the site glass (Pri & Sec), 5.5 to 6 PSI on the fuel rail gauge, no vacuum leaks... When I hit the throttle from idle to 1/2 open rather quickly, POP! Sometimes flames, sometimes just stalls. I cant figure this out. But when I put the Holley on, it screams! Snappy response, no hesitation, just rich smelling idle.

Is the carb just wrong for this application? The old Holley seems to work "OK" except for an eye-burning idle, and just seems a little bit restrictive at the top end now. Ignition system is a Jacobs Electronics/Mopar Electronic system combo, topped off with some MSD superconductor wires. Timing is set at 12 BTDC. Still don't have tape or dial timing light to check total, but since the old carb works, I would not suspect anything wrong with timing or anything else at this point.

I'm ready to send you both the MP distributor and the Demon, more for evaluation than anything else. I seriously believe I received a "Lemon" carburetor in this case. Too many other success stories to believe otherwise!

Is there anything else I can do? Anything to look for on the metering plates? Any specific passages that may be clogged up? Maybe the wrong metering plates are installed? At any rate, the idle circuit seems OK, but the cruise, power, and accel circuits seem to be fouled up some how.

Please Help! I have your phone number written down, but with your new business endeavor in the works, I'm not sure if this is the best time to call or not. Any advice would be greatly appreciated.

Thank
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  #2  
Old 10-24-2002, 02:08 AM
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cuda66273 cuda66273 is offline
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OK...first of all you need to have about 7#'s fuel pressure.

Are you sure you don't have some crud in the needle and seat?

Remove the float bowls and blow out the holes in the metering blocks...watch your eyes.

Check the jets for blockage.

Are you getting clean shot from the squirters?

Did you buy it from Summit? Did it smell of gas when you opened the box?

Even though we didn't sell it to you we will help you to fix it or get it fixed or replaced by the factory...just cause were nice guy's.

If you still can't make it work send it to me and I'll fix it N/C and we'll look at your distributor and if needed dial it in for you.
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  #3  
Old 10-24-2002, 02:38 AM
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gsmopar gsmopar is offline
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Cuda,

You should do a mail order deal for distributors. It seems like a lot of us may be in need of one of your "Cuda Curved" distributors.

Later,

Greg
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  #4  
Old 10-24-2002, 03:59 AM
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cuda66273 cuda66273 is offline
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Coming soon to an email box in your computer...what do you think I'm doing up until 1am?

Do I have your email address?
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  #5  
Old 10-24-2002, 12:41 PM
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gsmopar gsmopar is offline
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aultlt1@cox.net
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  #6  
Old 10-24-2002, 04:24 PM
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Default Thanks!

Yeah, it was a Summit order. We have been (off and on) working to get this running since last December! If this was a return and re-issue deal, it would explain a great many things.

I will be ordering your fuel line/filter upgrade as well. BG electric fuel pumps seem a little overkill, so, and I am thinking of a Carter mechanical street pump for it. (Although I have been debating with my wallet over just going to an electric/regulated setup!) Let me know what you recommend for my combo, I'll get it! Looking to keep 6-AN fittings throughout (Matching the fuel line that looks so nice at the carb.)

At any rate, having a 5 PSI reading at idle should be enough to at least goose this thing in neutral. But I agree, 5 psi is a little weak. The accelerator squirters seem very consistant, even with light taps, the fuel shot seems immediate.

I will take the carb off again tonight and dissasemble it, checking the needle/seat and blowing out all passages as you suggest.

HOWEVER!

mopar2u@covad.net is my e-mail box! Shoot me the address!

I expect you will be seeing my Distributor and Demon 2 days after I know where to send it, along with the order for the fuel filter/pump components! Are there any other details about the car I should collect and include with the distrubutor/carb I will be sending? If you need someone to setup a Word or PDF form to fill out, I could do that for you and e-mail it. You could provide it on-line for customer orders regarding distributor setup! Just a thought...(And I would feel like I was helping YOU for a change!)

Thank you VERY much for all your help!
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  #7  
Old 10-24-2002, 05:14 PM
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ehostler ehostler is offline
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Once things get moving at Too Much Racing, how much would it cost to recurve a MOPAR electronic distributor?
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  #8  
Old 10-25-2002, 09:41 AM
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cuda66273 cuda66273 is offline
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Eddy...Recurve a stock electronic distributor $99 and DOWN depends on how much we have to do to get it right.

Timty2:

You can email me at cuda66273@hotmail.com and I'll give you the shipping address in a couple of days, I just don't want anything shipped to the shop until we get the key's in our hand and the occupanct permit from the County and Firemarshall....you just never know if somethings going to go wrong at the last second.

A cgi progrogram would be great!

Would this be something that I could place in a post or would it be a download from a sticky?

Will I be able to copy it into my new website?

The M4268 Carter 120GPH mechanical pump should work for your stock 440....good fuel lines and a good filter will help even more.
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  #9  
Old 10-30-2002, 08:54 PM
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timty2 timty2 is offline
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I just wanted to thank Don (Cuda66273) for the words of encouragement, technical advice, and even putting the good word in at BG in helping me get this Demon dialed in. This kind of support is unheard off! I don't even really know this guy, and he's going above and beyond to help me out of this difficult situation.

When "Too Much Racing Technology" takes flight, the service and can do attitude will be a welcome addition to anyones "Ultimate Phone Book!"

For anyone needing Demon/BG parts or answers to your questions, Write this number down: TOO-TOO-QUIK
(866-866-7845)
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  #10  
Old 10-31-2002, 03:33 PM
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So what was the problem and solution? Thanks,
FB
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  #11  
Old 10-31-2002, 09:54 PM
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Just some machine chips in the float bowl threads causing havok as they released one at a time...He got it all cleaned out but needed a kit...Barry Grant had me send one immediatly to him to get him going and they sent me a another to replace it.

Just looking after the customer as fast and possible....
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