munday

should i just use my idle mixture screws? I just jetted it down tow the stock form, i think 68's and 72's. I followed lars tuning paper and i really wanna make sure i don't screw up, but at idle i get a decent amount of white smoke out the pipes, strong fuel smell.

could this be from my engine being new???


[Modified by munday, 2:00 PM 5/3/2004]

Vetterodder

Use a vacuum guage to adjust idle mixture and adjust for highest vacuum reading. As vacuum increases so will idle spped so you'll probably need to adjust the idle speed screw also. White smoke isn't from a rich mixture but from either oil being burned or from coolant getting into the cylinder. Oil will have a bluish tint but can be hard to tell from water. A rich mixture can smell pretty strong well before you can actually see it (black smoke). My guess is that you're smelling a rich mixture but seeing either oil or water being burned.

munday

well hopefully i am not burning oil, this is a crate motor with less than 120 miles on it. The exhaust diffenitly smells like fuel. The smoke is white. I notice no sweet smell. I see no bubbles in the oil. Could it be that my vavles just haven't seated yet? I am running valvoline straight 30 weight. Also I would think it had to be fuel related since I get the same amount of smoke out of both pipes and i do not have a cross over. My pipes just run straight back.

munday

Also I know what you are talking about from the blue smoke. My lightning would send out a huge puff of blue smoke every morning when I started her up from the oil leaking past the valves. Which leads me to believe this is not a vavle problem.

lars

munday -
If you're really getting white smoke out the pipes it's not a carb problem - you're either burning oil or antifreeze. If the carb is too rich you'll get puffs of black smoke when you flick the throttle - not white.

munday

it's wierd because it didn't do this before I adjusted the carb.

AKRAY4PLAY

does it smoke all the time, or just when the motor is cold/cool?? are you running cats?? mine smoked white at idle with a rich mixture, and black as coal when i hit the throttle. get the motor good and hot before adjusting the idle screws. Brian

munday

my engine doesn't seem to get over about 170 degrees, at least it didn't the other day when it was 80 degrees outside. And I didn't look when it was warmed up, but when it was cold it was white, and I just started her up to clean the undercarriage, and it was white out both pipes without giveing time to warm up. I will say the gas in the tank is about 5 months old. I don't know what it would matter. But like I said, what's wierd is that it is the exact (or as exact as my eyes can tell) amount of smoke coming out both pipes. All I can smell out the exhaust is fuel.


Do I just turn the idle mixture screws in to lean it up a little bit?

cmashark

munday, i know exactly what you are talking about. i put a demon on my 77 L82 and it started smoking. i readjusted the timing and played with the 4 mixture screws until it stopped. make sure the timing is adjusted with the vacuum advance disconnected, adjust the timing, then hook the vacuum advance to the ported vacuum port. i tried to use the on-line tech help from barry grant, but i fixed it before they emailed me back only to have them say to call them. it took almost 10 days for them to respond to my email.

chris :cheers:

AKRAY4PLAY

Demon carbs run rich out of the box. the idle screws are very sensitive to adjustment. so small steps in adjusting!! the white is water from the combustion process with rich condition. the water steams and you see white smoke. the smell is from raw fuel in the exhaust. a rich condition will also burn very cold and keep engine temps down. carbon build up and fuel in the oil are bad side effects from running rich. poor ecomony and performance are next. i would start at 3/4 turn on each idle screw, most Demons i have played with tune in around 1/2 to 5/8 turns, but they were on big cam low vacuum motors. the adjuster screws are easily damaged from seating and applying torque. be carefull not to damage the screw or seat when when finding zero on the adjustment. a phenolic spacer under the carb will help your tuning efforts, keeps the carb in a more stable temp range. best of luck, Brian