Need help with Mighty Demon 650

[RobbieH]

Hi all, I'm new here so don't be too evil ;)

I will be as detailed as I can possibly be.

I have a 383 stroker, Brodix heads, Victor Jr. intake, Hooker headers, MSD 6AL ignition with 6,000 rev limiter, 11.5:1 compression, roller lifters and unknown duration cam (but it's big), and 700R4 transmission (wish it was a stick).

Carb is Mighty Demon 650 as stated, engine idles with 9 inches in park, unfortunately I haven't had a helping hand to test in gear. I will state that even at 1000 idle RPM, it will die in gear, so I obviously do not have the right torque converter for the car, OR possibly there is a carb problem - this dying in gear is fairly new.

I've done about everything I can think of to set the carb right, but it constantly runs fat. If I drive my car, I come home smelling of fuel. The car has a horrible off-idle hesitation, but my floats are set correctly (just over the middle mark) and the accellerator jets are working as designed as well.

I talked to someone today, and they said I might have the wrong power valve. I am not sure yet (will take it apart soon) but I believe it to be the stock 6.5 valve.

In park, a quick blip of the throttle will take vacuum to zero. I should also mention I am not running any accessories off engine vacuum, I have an electric vacuum/reservoir setup to run the brakes.

It may or may not be related, but when the car is cruising at anything not requiring throttle, the car surges.

I am completely open to suggestions and will try just about anything to get this thing running right.

One more question, are the power valves in the Demons the same part as what is in a Holley?

Thanks all, here's a pic of my engine bay in case it helps at all.

[Shaker455]

Robbie,
If it dies in gear then the mix screw may not be set right.

Surging @ cruise may be a sign of running lean despite you comming home smelling like exhaust.

Pop some plugs and tell me what color they are?

How many turn out are they?

Where's your timming at?

I see you have an MSD so where's your initinal, color bushing & springs?
Jeff

[RobbieH]

I should note, I believe this car has a stock torque converter, and as such putting it in gear drops the RPMs.

I will pop some plugs ASAP and get pics posted.

The timing is set correctly according to the shop I took it to. I will get my light on it and get that information for you.

I'm not familiar with the color bushing and springs, can you share some more info on this? If I know what you mean, I can get the info for you. I'm new to the MSD.

[surnufz]

If the carb has the 4 corner idle circuit, turn each screw all the way in and back it out 3/4 turn. Then set the timing at 12 degrees BTDC. This should get you close. If it has been running rich, it could have fouled the plugs. If that is the case, they will need to be changed. (if they are dark grey to black and sooty looking, they are fouled)

[RobbieH]

I apologize, I forgot to mention all 4 corners are 3/4 out. I have checked the plugs before now and they look good (not fouled) but I forget what color they are. Changing 3 of them requires removing the headers (ugh).

Another item I forgot to mention, I have a question about the way the vacuum on this car is set up. Evidently the car runs zero vacuum at idle, so the previous owner connected an auxiliary vacuum pump to the manifold so the power brakes would work. You can see the pump on the bottom right of the picture. With the pump running, the engine shows 9 inches of vacuum at the manifold port. Is this pump connected properly? Could it be part of the problem?

[surnufz]

Make sure the coil wire is pushed all the way in. (looks like it might be loose)

[Shaker455]

Your engine should be making some vacuum and if the cam is really large then the initinal timming should be atleast 18 degrees and less initinal will make less vacuum.

So you need to know where your at there.

The MSD can be curved to your combo and from the factory they come with different color advance bushings for different amount of mech advance.

Also they have color coded springs to give you different rates of advance to again taylor in your combo.

Here's a link to the instruction sheet: http://www.msdignition.com/instructiondownload.aspx

Pop off your cap & rotor and look at the springs, the bushing you may not be able to see but once you look at your initinal & total timming we can figure whats in there.

Also, does that dist have a vacuum advance or not?

Are any plug wires contacting the headers?