dartbrad66
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Hey guys, how's it going? What are some symtoms of a lean and rich mixture. I am having a hard time tuning my carb.
symtoms of lean and rich mixture
- Thread starter dartbrad66
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69signetv8
Well-Known Member
Depending on you carb, the link below will help in the correct setup.
http://automotivemileposts.com/garage/v2n8.html
http://www.farmallcub.com/ts_engine.htm
http://automotivemileposts.com/garage/v2n8.html
http://www.farmallcub.com/ts_engine.htm
340mopar
Sorgermotorsports
The smell of gas is not a good indication of a rich/lean condition. You can have a gas smell if it is lean too. If your engine is in a lean condition to the point of a lean misfire in a cylinder it will send the unburned fuel into the exhaust just like an incomplete burn of fuel in a rich condition.
69signetv8
Well-Known Member
OK, Agreed :thumblef:340mopar said:
68gts340
Well-Known Member
this may help a little...... running rich. black sooty spark plugs, exhaust will smell like fuel, also may have black smoke from tail pipes. hard starting that may be helped by holding the pedal to the floor and cranking over motor (flooded )
lean.... exhaust stinks, may smell like rotten eggs . white spark plugs, the plugs may even have small spots on them, spots are not good ,may be piston particles.
carb back fires are normally a lean condition or a vaccum leak. a lean carb may surge a cruising speed with steady throttle, lean can also cause over heating.
to fix......verify before changing the carb. check your engine grounds, you need to have a ground from block to body, next check charging system and battery, next check the ignition , and timing.....if any of these are not right you will go nuts trying to fix the carb... take a few minutes and save a few hours.....
heres a couple quick tricks to get a general idea of a rich or lean condition...
if it is rich ..slip off a small vaccumn cap or line. this will add air and lean it out some... engine will respond by running smoother and may raise idle a bit ..
if it is lean.... you can richen it a little by closing the choke a little bit by hand, or use your hand to restrict the air flow. engine will respond by picking up idle and/or smooting out.
smelling the exhaust is the easiest. if you do not know how it should smell, just sniff the tailpipe of a good running car.
last.....watch the spark plugs... white after running is no good.. actually dangerous to pistons. again to lean..
black plugs.... means unburned fuel ....to rich
tan or light brown plugs ....this is what you want to see.....
hope this will help ..sorry it is so long.........Ron
lean.... exhaust stinks, may smell like rotten eggs . white spark plugs, the plugs may even have small spots on them, spots are not good ,may be piston particles.
carb back fires are normally a lean condition or a vaccum leak. a lean carb may surge a cruising speed with steady throttle, lean can also cause over heating.
to fix......verify before changing the carb. check your engine grounds, you need to have a ground from block to body, next check charging system and battery, next check the ignition , and timing.....if any of these are not right you will go nuts trying to fix the carb... take a few minutes and save a few hours.....
heres a couple quick tricks to get a general idea of a rich or lean condition...
if it is rich ..slip off a small vaccumn cap or line. this will add air and lean it out some... engine will respond by running smoother and may raise idle a bit ..
if it is lean.... you can richen it a little by closing the choke a little bit by hand, or use your hand to restrict the air flow. engine will respond by picking up idle and/or smooting out.
smelling the exhaust is the easiest. if you do not know how it should smell, just sniff the tailpipe of a good running car.
last.....watch the spark plugs... white after running is no good.. actually dangerous to pistons. again to lean..
black plugs.... means unburned fuel ....to rich
tan or light brown plugs ....this is what you want to see.....
hope this will help ..sorry it is so long.........Ron
moper
Well-Known Member
I've found sniffing the exhaust only good for idle mixtures, which can be a problem with other-than-stock camshafts. Use the spark plugs. Set the timing first, then set the carb with a vaccum gage for the highest reading at the specified rpm..I like to stay under 850rpm, 650-700 for a stock engine. Once that's done..replace the plugs. Then, take the car for a ride. Bring a sprak plug socket, and stop after a few miles of mixed throttle driving. Pull a plug..Watchout, very hot, so use an extension and/or mechanic's gloves.. As they said, it should be tan..the lighter the beter, IMO, but it should have some color. very lean can cause surging, intermittent misses, studders, and running hot, in addition to issues with bearings, pistons, and rings. Too rich is loss of efficiency and power, ignition issues, in more extreme cases ring damage , and visual clouds of smoke and black deposits on the rear end of the car..(Seen a TON of car show vehicles with that...)
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