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Incorrect timing can lead to the fuel being ignited before the manifold intake valve closes, causing a backfire through the carburetor or exhaust. Holes in the pipe leading to intake manifold may result in an increase inflow of air, which unbalances the air-fuel mixture ratio. A leaner ratio is more volatile, and more likely to cause backfires.


Why does my engine spit or backfire? First off, you need to determine whether it is backfiring out the exhaust or back up through the carb. We usually refer to an exhaust backfire as a "backfire", and backfiring through the carb as "spitting" or "coughing".


My 70 El Camino started backfiring quite badly through the carb with a ball of flame coming out. The carb has been running rich it seemed lately as there is a lot of carbon coming out of the tail pipe. The car prior to the carb being rebuilt was running rich and after the rebuild seemed better but then starting running rich again.


Backfire is a condition described as a loud bang, poof, explosion, etc., while the engine is running or while shutting down. Afterfire occurs after the engine has been shut off. Note: Backfire and afterfire through the carburetor will not harm the engine at all! Find out the most common causes and possible fixes for engine backfire and afterfire.


Troubleshooting - backfire through carburetor . By: Bill Tichenor 12/02/2009 < Back to Blog Home. Footage taken from Holley Carburetor Installation & Tuning DVD ... Either way a leaky fuel bowl on your carburetor, probably isn’t going to end well. But a stripped bolt doesn’t mean you have to trash your carburetor and buy a new one.


This upsets the air-fuel ratio and causes too much air to be mixed with the fuel, resulting in what is known as a lean running condition. The leaner fuel and air mixture is more volatile than the proper mixture and causes premature ignition, or pre-ignition of the mixture, resulting in backfiring through the tailpipe.


The factory Evolution engine's ignition can contribute backfiring through the carburetor. Cam design: Long duration cams with early opening intake valves can contribute to backfiring. Intake manifold air leak: A lean condition due to an intake manifold air leak can cause backfiring.


A back-fire or backfire is combustion or an explosion produced by a running internal combustion engine that occurs in the air intake or exhaust system rather than inside the combustion chamber. Unburnt fuel that are ignited in the exhaust system can produce loud sounds even if flames are not present at the tailpipe.


Understanding the Backfiring Mechanism. Backfires are always accompanied by a loud, popping sound and many a times with a visible flame, referred to as the after-fire. This after-fire is a by-product of backfiring through the exhaust, something that was a common sight in older car models.