smoking issues timing issues
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smoking issues timing issues
hello.I know this is a kind of vague question, but could timing being off cause smoking in my engine. i have a rebuilt 351M in my 74 F100. Also, it's making a clicking noise. I read in my Haynes manual that bad timing could cause that, and i know the timing is off cause it won't even idle. i have to sit in the truck and keep my foot on the accelerater just to keep it going. (just bought this engine and just got it set in the truck couple weeks ago). But could the timing issues cause it to smoke too? (side note: the modulator valve on the trans was bad and it was sucking trans fluid into the engine making it smoke like crazy. replaced it tonight. ran it for about five min and still smokes) If i need to include more info let me know. Any help is appreciated. Thanks in advance.
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
There are two cases of smoking - burning something you shouldn't be burning, or not burning enough of something you should be burning. If the smoke is white, that means you're burning coolant, which can be caused by a bad head gasket. I think trans. fluid burns white as well. If the smoke is blue, that means you're burning oil, which can be caused by valve guides or rings. If the smoke is white or blue, it can't be related to timing.
If the smoke is black, you're running rich, and in some instances it could be caused by an incomplete burn due to the timing being off. However, this is pretty unlikely. So I'm going to go with a no on this one. It's a moot point though - why even wonder? Set the timing to the factory specification with a timing light and then take timing out of the equation.
As far as having to feather the pedal, that's usually a carburetor issue - choke stuck one way, idle too low, bad idle mixture, vacuum leak...the list goes on.
If the smoke is black, you're running rich, and in some instances it could be caused by an incomplete burn due to the timing being off. However, this is pretty unlikely. So I'm going to go with a no on this one. It's a moot point though - why even wonder? Set the timing to the factory specification with a timing light and then take timing out of the equation.
As far as having to feather the pedal, that's usually a carburetor issue - choke stuck one way, idle too low, bad idle mixture, vacuum leak...the list goes on.
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its not stock. It has an edelbrock performance intake and 4bbl carb. As far as the smoking goes theres one other thing i forgot to mention earlier. the exhaust manifolds on both sides are leaking something out...looks like burnt oil. they're leaking around the bolts. there's a gasket there, but it doesn't seem to be holding any of it in, not that anything it should be leaking out anyway, but thought i'd mention that too. any idea what could be causing that?
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
No offense man, but it's pretty bad practice to say "it's supposed to run poorly." That's not the case. Stock Ford 2-barrel carburetors are excellent-performing carburetors. If it's not performing properly, there is a problem. These carburetors get a bad rap because people who don't know what they're doing have trouble with them and blame their incompetence on the carburetor. I'm not saying you don't know what you're doing, but I'm trying to stop this stereotype.
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well guys i don't know much about those 2v carbs, but could we save any arguments for another post? I wonder if anyone has any ideas about my exhaust manifolds and what's leaking out of them and why it's doing that. any help is greatly appreciated
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Joined: Jan 2009
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From: Phoenix Arizona
I got my 75 F-100 a couple of months ago and where I bought it was about 2000 feet in altitude lower then were Iam. I had to have the carb leaned out to stop my smoking it is also an Edelbrock,I know the mechanic changed the jets and adjusted the mix. As for the exhaust could it just be oil ozzing down off the valve cover or maybe old gasket sealant coming out?
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MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
It's probably oil leaking from underneath the valve covers. Nothing can leak "through" the exhaust manifold bolts. What color is the smoke, and is it coming from the tailpipe or wafting off the engine?
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From: Utah
Rebuild the carb
The carb leaking internally or having a stuck ball valve can cause this. It will run extremely rich and won't idle. It sucks a huge amount of gas through the engine and makes a lot of sooty smoke. Rebuild the carb. I've never rebuilt an Edelbrock carb, but it's usually pretty easy and worth it. See my post on my experience with this. Change the oil after because it's probably ruined by being diluted with gasoline.
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Fmc400: The smoke is coming out the tailpipes, and it is not drpiiping down from the valve covers, I'm sureof it. haven't really had the chance to see the true colorof the smoke i've been working on it at night, may get some time to look at it in the daylight today and will get back on and post more info.
Jeffomatic: I think you're right!!! the oil does have a gasoline smell to it.. But it is a newer carb. you think it just need adjusting? or does it need rebuilt?
Jeffomatic: I think you're right!!! the oil does have a gasoline smell to it.. But it is a newer carb. you think it just need adjusting? or does it need rebuilt?
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From: Western N.C.
btorear- do your duals have a crossover pipe? If so, you may have a problem in only one area and it is being transmitted out of both pipes.
Still, I remember about ten years ago my uncle's wrecker started doing the same thing. Turned out he had a two broken piston compression rings...one on each side.
This would cause your symptoms also.
1. oil smells like gas- fuel leaking down past broken rings into crankcase
2. engine produces lots of smoke- broken rings have scored cylinder(s), causing poor oil control
3. engine will not hold an idle- compression bottoming out in one or more cylinders
4. oil coming out of exhaust manifold(s)- again, poor oil control being translated into oil being blown out of cylinder(s)
5. clicking noise- broken ring(s) chattering around inside cylinder(s)
You said that this engine was rebuilt- do you know how many miles are on it? It could be that it was not broken in properly and that the rings have not seated right. You may also have glazing in your cylinders.
As you know, auto tranny fluid makes a poor engine lubricant. If the sucking and burning went on for awhile, it may have scored your cylinder walls.
I'm not saying that this IS your problem, but if all else fails to resolve the problem, start checking your cylinder compression.
Still, I remember about ten years ago my uncle's wrecker started doing the same thing. Turned out he had a two broken piston compression rings...one on each side.
This would cause your symptoms also.
1. oil smells like gas- fuel leaking down past broken rings into crankcase
2. engine produces lots of smoke- broken rings have scored cylinder(s), causing poor oil control
3. engine will not hold an idle- compression bottoming out in one or more cylinders
4. oil coming out of exhaust manifold(s)- again, poor oil control being translated into oil being blown out of cylinder(s)
5. clicking noise- broken ring(s) chattering around inside cylinder(s)
You said that this engine was rebuilt- do you know how many miles are on it? It could be that it was not broken in properly and that the rings have not seated right. You may also have glazing in your cylinders.
As you know, auto tranny fluid makes a poor engine lubricant. If the sucking and burning went on for awhile, it may have scored your cylinder walls.
I'm not saying that this IS your problem, but if all else fails to resolve the problem, start checking your cylinder compression.
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Well, I've found my problem, and I'm almost too ashamed to tell it in this post. Am i a rookie? ...Yes. Am i this green of a rookie? ... no. Well, my edelbrock carb had an inlet for fuel and an inlet for the pcv line. I had them reversed. Yes...to answer any questions. i am dumb as a rock. The engine did run with this set up...how i couldn't tell ya. I figured it out when i drained the oil out. well it wasn't like any "oil" I'd ever seen. i didn't have time to change the oil again and swap the lines to their proper places, so I don't know what kind of damage i've done. I did run the truck like this for less than 15 min total over the past two or three days. and once revved it full throttle. I'm very angry with myself about it, but i'll know more when i get the set up right and some fresh oil in her. Any ideas about what kind of damage i may have done?
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From: Western N.C.