Hipturd
New Member
Every cold start on my LA 318 2 bbl I get this residue out of tailpipes, anyone know what’s going on and remedy? Thanks
Cold Start Exhaust Residue??
- Thread starter Hipturd
- Start date
Normal during cold starts with choke still on with some unburnt gas.
As the engine warms up and the choke slowly opens up,the exhaust cools and condensation forms and thus leaving a carbon footprint.
If anything,make sure the choke and carburetor are set properly if you think it is too rich.
As the engine warms up and the choke slowly opens up,the exhaust cools and condensation forms and thus leaving a carbon footprint.
If anything,make sure the choke and carburetor are set properly if you think it is too rich.
Warm/hot exhaust hits cold steel exhaust pipe. Condensate occurs and usually collects in the muffler. Which is the reason for the small pin hole on the bottom of Chrysler mufflers, so the condensate can drip out. Condensate washes the inside of the pipes, which leaves the "trails" you illustrate. Completely normal, but a bit messy sometimes.
The other thing is that you should be DRIVING the car as it warms up, not letting it idle and warm up. In that orientation, the gasses get the pipes hotter quicker, possibly, so no "tracks" as illustrated. The side with the less track is the side with the heat riser. Heat riser closes and sends most of the exhaust to the opposite side, via the heat crossover in the cyl heads and intake manifold.
One of the flakiest things to watch is a late model Toyota as it is being driven around the sales lot, first start in the morning. Lots of condensate made, which collects in the muffler. A quick throttle input can result in a quart of so of clear water dump out of the end of the tail pipe.
DO ensure the choke is operating as designed. Might even clock the thermostat for the choke two notches leaner, for good measure. Then make sure that as things heat up, the choke will gradually open fully.
Enjoy!
CBODY67
The other thing is that you should be DRIVING the car as it warms up, not letting it idle and warm up. In that orientation, the gasses get the pipes hotter quicker, possibly, so no "tracks" as illustrated. The side with the less track is the side with the heat riser. Heat riser closes and sends most of the exhaust to the opposite side, via the heat crossover in the cyl heads and intake manifold.
One of the flakiest things to watch is a late model Toyota as it is being driven around the sales lot, first start in the morning. Lots of condensate made, which collects in the muffler. A quick throttle input can result in a quart of so of clear water dump out of the end of the tail pipe.
DO ensure the choke is operating as designed. Might even clock the thermostat for the choke two notches leaner, for good measure. Then make sure that as things heat up, the choke will gradually open fully.
Enjoy!
CBODY67
Loadrunner
Active Member
It's because you're too far north, from the Great White North ;]
Wait a couple decades, it'll be like Mexico and you won't have the problem anymore.
Wait a couple decades, it'll be like Mexico and you won't have the problem anymore.
Hipturd
New Member
Actually my Fury is quite spoiled, she spends every night in a heated garage
Hipturd
New Member
The mufflers just got replaced so maybe I’ll try drilling a hole in each, if they don’t have any
Hipturd
New Member
Is the mixture screw the one in front of the carb at the bottom and do you adjust it while running? I don’t know if it is the choke bc the soot only comes out immediately after start up.
Hipturd
New Member
I don’t think it is burning oil , haven’t noticed any smoke during start up or while driving
jollyjoker
Active Member
Nothing new! Back in the day, dad had a brand new 65 Monaco (383) - and shortly thereafter we developed an ever-enlarging black circle at the edge of the garage, where the car would fire-up every morning. Before long, a neighbor (Mario) saw it, and would always enjoy calling out: "Hey there, whatcha burning in that thing - kerosene?" Odd thing, that was the only care we ever had that did this . . . Thanks for the memories!
1970FuryConv
Old Man with a Hat
I agree with too rich, especially left side (driver side) of carburetor. Look at the difference between the black 2 carbon marks on the driveway.
66 Monaco 500 365
Member
It seems like the choke pull off is not opening the choke blades far enough when the engine starts
My $.02
My $.02
68PK21 440.6bbl
Old Man with a Hat
Time to get it out on the highway and 'Blow The Carbon Out Of It'!
1970FuryConv
Old Man with a Hat
How many turns out early idle mixture screws?
If unknown, you can turn each screw clockwise until it seats, while counting the number of turns.
When I got my 1972 Fury, the left side idle mixture screw was like 2.5 turns and the right side was like 1.25 turns. I had a big carbon mark on my garage floor below the left side pipe.
For setting idle mixture, I usually put a vacuum gauge on the manifold vacuum port at the carburetor.
Then turn each idle mixture screw out from say .5 turns until I get Max vacuum.
Usually this is between 1.0 and 1.5 turns out from seated on both idle mixture screws.
Basically, you turn the idle mixture screws out until it reaches Max vacuum. Then you find that turning them out more doesn't increase vacuum. Then you go back to the amount of turns that initially gave you Max vacuum.
If unknown, you can turn each screw clockwise until it seats, while counting the number of turns.
When I got my 1972 Fury, the left side idle mixture screw was like 2.5 turns and the right side was like 1.25 turns. I had a big carbon mark on my garage floor below the left side pipe.
For setting idle mixture, I usually put a vacuum gauge on the manifold vacuum port at the carburetor.
Then turn each idle mixture screw out from say .5 turns until I get Max vacuum.
Usually this is between 1.0 and 1.5 turns out from seated on both idle mixture screws.
Basically, you turn the idle mixture screws out until it reaches Max vacuum. Then you find that turning them out more doesn't increase vacuum. Then you go back to the amount of turns that initially gave you Max vacuum.
If the exhaust heat valve is working correctly, most of the exhaust will be exiting the left side on cold start up.
1970FuryConv
Old Man with a Hat
Good point, thanks!
I still think he should check idle mixture with procedure in my last post.
Also, I still think the car is running rich. We'll have to see if he reports what he finds.
Philip Andrews
Well-Known Member
If it's only doing short runs and is left to idle and warm up it'll soot the exhaust.
I find summer mix gas in cooler weather does this, recently my driveway has regained its' sooty marks.
Winter they go away. Summer they go away. Fall is when they appear, and it's not exactly cold down here.
My plugs and nose tell me it's running fine when up to temperature.
The remedy for no sooty marks, park it up and don't drive it, ever.
Don't worry about it, pretty normal on modern fuels.
Phil
I find summer mix gas in cooler weather does this, recently my driveway has regained its' sooty marks.
Winter they go away. Summer they go away. Fall is when they appear, and it's not exactly cold down here.
My plugs and nose tell me it's running fine when up to temperature.
The remedy for no sooty marks, park it up and don't drive it, ever.
Don't worry about it, pretty normal on modern fuels.
Phil
marty koirtyohann
Well-Known Member
valve seals? u know over time the rubber valve seals dry out & get hard . that it what it looks like to me . but then some motors do that the motor is cold & so r the pipes . ir called condensation my 72 new yorker does much like the something & its had less than 30k on the rebuild that i did it all myself
Hipturd
New Member
My 65 with the 72 LA 318 engine is getting about 12 mpg on the highway at 55 mph, do you think should be getting better mileage?
marty koirtyohann
Well-Known Member
well i depends what gear is in it? the 72 318's was smogged out they cut the compression while a 70 318 in a dart with 3.23 gears would get 20 MPGs but it made more horse too (235 veris 190 in 72) IN A 3800-4000# B BODY THE 66 318 GOT 15 + MPGs it has to due with & hp. putting a smog 318 in the older car was ok but rebuilding the factory motor would had been better . & how many miles r on it iit its 50k i bet it needs valve seals & if its close to 90-100k then its timing chain time put a double row one in u will never have to replace it . if u dont when it throws the chain & it will then it will bend every valve in the motor costing u way more . how mechanical inclined r u ? can u tear the motor down & rebuild it?
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