| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#1
09-19-2015, 08:31 PM
|
||||
|
||||
SMOKING AT IDLE
I have a 70 GTO carb rebuilt using kit from Cliff. can't get it to stop smoking. As soon as it warms up it is like a cheech and chong movie.Car runs great-plugs clean. not using oil or coolant. Exhaust smells like fuel. Does not smoke when driving. Only at a light or at idle. Engine rebuilt- has less than 1000 miles. Any help would be appreciated before it becomes a very expensive boat anchor. Rebuilt the carb due to a hesitation on acceleration, which for the most part is cured after rebuild. Cant see it being anything but fuel related.
|
|
#2
09-19-2015, 11:15 PM
|
||||
|
||||
|
Pull the hose off down at the trans modulator and see if trans fluid comes out.
__________________
Bull Nose Formula-461, 6x-4, Q-jet, HEI, TH400, 8.5 3.08, superslowjunk |
|
#3
09-20-2015, 03:11 AM
|
||||
|
||||
|
What color is the smoke?
__________________
 1965 Pontiac LeMans. M21, 3.73 in a 12 bolt, Kauffman 461.
|
|
#4
09-20-2015, 06:13 AM
|
||||
|
||||
|
If it smells like fuel out the exh when warmed up then you are fuel washing the needed oil for piston and ring lube off of the cylinder walls and burning it!
Cylinder walls will go south quite fast with this condition as the needed crosshatch gets worn away and then the motor will burn even more oil with little to no crosshatch when up to normal operating temps! I would bet that your carb is so rich at idle that your could cold start the motor with little or no choke, just a tap of the gas pedal . |
|
#5
09-20-2015, 07:42 AM
|
||||
|
||||
|
Should have mentioned it's a 4 speed car... Smoke is a greyish white color.
Steve the car starts normally all the time, not using any oil. I am all over the place with this issue. |
|
#6
09-20-2015, 07:47 AM
|
||||
|
||||
|
With the motor fully warmed up does spinning the idle mixture screws 3/4 of a turn both ways make the motor run ruff and or shut off which is as it should be?
What else has been done to the motor other then the Carb rebuilding, and where there any issues Carb or motor wise before all if this?
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
|
#7
09-20-2015, 08:18 AM
|
||||
|
||||
|
Steve, yes, turning mixture screws does affect engine as it should. Carb was rebuilt due to hesitation on accelleration. No other issues prior.
|
|
#8
09-20-2015, 08:22 AM
|
||||
|
||||
|
I have just shy of 20 inches of vacuum, however guage is not steady, kinda jumps around slightly. but does not seem to have a vacuum leak. The car runs great, almost as if it is fuel injected, but can not clear up the smoking
|
|
#9
09-20-2015, 08:33 AM
|
||||
|
||||
|
What are the engine specs?.....
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
|
#10
09-20-2015, 08:39 AM
|
||||
|
||||
|
Hi Cliff, stock 400 4 speed
|
|
#11
09-20-2015, 08:47 AM
|
||||
|
||||
|
Check or replace your PCV
__________________
Carburetor building & modification services Servicing the Pontiac community over 20 years |
|
#12
09-20-2015, 09:18 AM
|
||||
|
||||
|
Quote:
400 Stroke Bore Heads Cam qjet Compression spark plugs Intake Ignition lifters What oil you running timing Fuel octane Standard Just a few things..  Charles I would also say check the PVC system out to make sure it's working. I worked on a friends car not too long ago that was smoking at idle with no pvc system hooked up.
__________________
68 Firebird. IA2 block, 505 cu in, E-head, Solid roller 3650 weight. Reid TH400 4:11 gear. 29" slick. Best so far 10.12@133 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
|
#13
09-20-2015, 10:18 AM
|
|||
|
|||
|
Is gas dripping while idling ? Did u jb weld the well plugs?
__________________
 1970 amc rebel 4-door, faded blue paint,290 emblems on car, 455 under the hood.Turbo 400,3.15 gear.Best so far 1/8 et,8.90 on street tires, Since that I have added 400 heads. I call it a rat sleeper. |
|
#14
09-20-2015, 02:01 PM
|
||||
|
||||
|
"Steve, yes, turning mixture screws does affect engine as it should."
Having full control of idle fuel and being able to turn the mixture screws in and slow the engine down indicate you can go lean with it, so it shouldn't be smoking out the pipes, unless it's burning oil from someplace.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
|
#15
09-20-2015, 02:59 PM
|
||||
|
||||
|
Cliff, i would agree, but it is clearly fuel.Not using or losing oil or coolant. Pretty sure this started after carb was worked on.
|
|
#16
09-20-2015, 03:17 PM
|
|||
|
|||
|
you said the smoke is a greyish white color -- wouldn't excess fuel burning make dark gray or black exhaust smoke (rich condition)? white-ish usually means coolant burning.
|
|
#17
09-20-2015, 04:35 PM
|
||||
|
||||
|
Yeah - excess fuel would be black smoke. I've never seen a car belch black smoke at idle due to lower fuel flow. (You have to give it some gas to get enough fuel flowing for smoke)
In my experience, coolant is cloud white and sweet smelling. Oil is grayish white. It doesn't take a lot of oil to produce smoke - that could be why you're not seeing it on the dipstick.
__________________
1965 Pontiac LeMans. M21, 3.73 in a 12 bolt, Kauffman 461.
|
|
#18
09-20-2015, 04:36 PM
|
||||
|
||||
|
Going too lean can actually make the exhaust smell worse than a tad rich. I'd tune the idle A/F for best idle quality and highest vacuum at the leanest settings, making sure you aren't setting the mixture screws lean enough to reduce engine rpm at idle.
Excessively rich from the carb's idle fuel system and you not have any control with the mixture screws, and it would still be stinky, and black/sooty exhaust even with the mixture screws fully seated......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
|
#19
09-20-2015, 06:26 PM
|
|||
|
|||
|
Plug your pcv line and try it.
__________________
1970 amc rebel 4-door, faded blue paint,290 emblems on car, 455 under the hood.Turbo 400,3.15 gear.Best so far 1/8 et,8.90 on street tires, Since that I have added 400 heads. I call it a rat sleeper. |
|
#20
09-20-2015, 07:46 PM
|
|||
|
|||
|
burning oil is usually greyish-blue, can be worse at idle and first take off but not seen later during driving, and may not be noticable on the dipstick until after several hundred miles.
|
| Reply |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Linear Mode
