As another poster mentioned, I would check for manifold vacuum leaks and also see if the timinig is set right. While there is a lot of "audio information" in your video, I, personally, wasn't able to discern as much as I would hope to have. It's just that there is so much distortion in the sound when recording on a tiny microphone. When you held the camera by the tailpipe, I thought that maybe the timing sounded somewhat retarded.
A retarded spark will make an engine sound like it has a little "lope" to it at an idle. A sound similar to a high performance cam. That didn't seem to be the case when I heard the sound of the engine from under the hood. I'm afraid that you are just going to have to learn how to use a timing light accurately and confidently.
When you are confident that the timing is correct, then a search for a vacuum leak or carb problem can be undertaken. In advance of that I'll offer that I'm thinking that it's less likely that there is a burnt valve if you feel that all of the plugs looked pretty much the same. Weak valve seals will cause an engine to puff out smoke after accelerating from an idle. I don't think that I have ever known them to cause the amount of oil consumption that you are indicating, though.
I spent a good deal of time under the hoods of cars of this era and even Ford sixes that were running wonderfully still seemed to have a whole lot of blow-by coming out of the breather cap.
While it's true that engine timing rarely wanders off by itself, worn or improperly set points change timing quite a bit. I would suggest that you start with new points and plugs, also look at the cap and rotor. Then set the timing even if you have to invest some time in learning how. After that, return here and one of us will gladly take the time to talk about using a Burnz-A-Matic to locate vacuum leaks.
This sounds interesting? The way it is smoking tells me the rings are bad. What else it needs, hard to say without taking the engine apart. You need to be a member in order to leave a comment. Sign up for a new account in our community. It's easy! Already have an account? Sign in here. What causes a carb to backfire?
Share More sharing options Followers 2. Recommended Posts. Lebowski Posted November 22, Posted November 22, Link to comment Share on other sites More sharing options Mark Shaw Posted November 22, Lebowski Posted November 23, Posted November 23, AlCapone Posted November 23, A very lean mixture or timing. Didn't hurt to check the timing regardless. Hudsy Wudsy Posted November 23, Also, make sure that the carb base nuts are tight. Posted November 23, edited. Edited November 23, by carbking see edit history.
Suggestion: buy some test equipment. Edited November 23, by Lebowski see edit history. Lebowski Posted November 24, Posted November 24, Of course a Rochester FI at psi is different. Posted November 24, edited. John Posted November 24, The ignition timing seldom ever just goes off on it's own, and even less seldom to coincide with the replacement of the carburetor I had encountered a similar problem and it turned out that some paint over spray from the rebuilder was on the inside of the carb, The solvent action of the gasoline lifted it up causing it to float around the bowl until it clogged up the metering jet.
Edited November 24, by John see edit history. Buffalowed Bill Posted November 24, MCHinson Posted November 24, AlCapone Posted November 24, I'll do it for nothing if you pay my air fare from Canada and put me up for the winter. Hudsy Wudsy Posted November 24, Edited November 25, by Hudsy Wudsy see edit history. Curti Posted November 25, If it sparks when the intake valve is open, you're going to get a pop back up through the carb.
If it sparks when the exhaust valve is open, then it'll cause a bang out the exhaust. Basically, when that plug sparks out of turn, it lights the fuel in the cylinder - and that pressure has to go somewhere This usually goes away once the engine warms-up. A cold engine needs more fuel to run, and a warmer engine runs more efficiently and needs less fuel, so if you are only spitting when the engine is cold, then most likely it's due to a lean condition. You could also check to make sure your choke is working.
If it's stuck open when the engine is cold, then it isn't doing its job by richening-up the mixture and it could definitely cause spitting. The exploding mixture then vents through the carburetor. Improper carburetor adjustments or vacuum leaks can cause this condition.
Cause of Backfiring Since the intake valve needs to provide the engine with a proper balance of fuel and air, a backfire occurs when that balance fails.
In this case, having less fuel than air in the mixture will cause the small explosion. A backfire is caused by a combustion or explosion that occurs when unburnt fuel in the exhaust system is ignited, even if there is no flame in the exhaust pipe itself. Sometimes a flame can be seen when a car backfires, but mostly you will only hear a loud popping noise, followed by loss of power and forward motion.
Can bad spark plugs cause backfire? If your fuel pump is failing, it will need to be replaced immediately. If your vehicle is equipped with a fuel injection system, make sure that it is cleaned and maintained regularly. A clogged fuel injection system will not burn fuel completely and can cause backfires.
A leak in the injection system, usually the result of a stuck air intake valve, is another common source of backfires. Using fuel injector cleaner might take care of the problem.
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