I am new to adjusting carbs and I need some advice. I just put a 650 mighty demon on my car and I believe it's running very rich. The back to cylinders are getting heavy sooty deposits on them and the car dosent idle at all. my car recently wasnt firing on 2 differnet cylinder's due to the depoist's on the spark plug's I have recently change them but the are starting to get black also. Any help would be great .

 

idle mixture screws will need to be set. this will also effect cruise at part throttle. initial ignition timing has alot to do with running rich and poorly. meaning if you have a larger than stock cam base timing needs to come up alot more than a stock 6 degrees btdc.

make sure the throttle blades are not to far open causing rich running. make sure your power valve is the correct one and not activating at idle.

also pick up some reading material and start tuning........

 

Well I have this cam http://static.summitracing.com/globa.../lun-00012.pdf

I believe I have 4 degres intial timing and 38 total. Does that sound right ??

 

no.
you will be lucky to pull away from a stop sign with that cam with only 4 degrees initial ignition timing. i would put it more like 20 degrees initial 38 total.

I hope you got a 3000 stall converter and some 3.73 gears for this cam as well.
246 at .050 is alot of duration for a street driven 350ci. idle vacuum is going to be really low.
hows your power brakes?
whats the rest of your setup contain to go along with this cam?

 

Well I am guessing on the timing I didnt do it my buddy did and the car ran well when we broke the motor in so I am guessing its ok. I will re check the timing with my buddys timing light to make sure and I just remembered the my distributor has no vac advanve also. Its a profrom racing distributor with light springs in it if that matters. Yes i do have a 3000 stall but I only have 3.23 gears now next year I am have my 10 bolt rebuilt for posi and 4.10 gears. I havent driven the car yet I cant seem to get the shifter linkage to meet the new tranny, Its missing by a 1/4 of an inch. And the rest of the setup for the motor is

650 mighty demon carb
1 inch hvh street sweeper
weiand stealth intake
dart s/s heads with 2.02/1.60