The Ford Barn - View Single Post - 1930 Sport Coupe 11 MPG, backfire when turned off

rotorwrench · 08-01-2020, 10:12 AM

Some folks refer to an after fire as a backfire. The exhaust should be mentioned if the backfire term is used or there can be a misunderstanding. The actual backfire through the throat of the intake manifold sounds more like a hickup so this leads to the confusion. The actual backfire is a sign of a lean condition under any form of load.

11-MPG is indicating a rich condition unless the vehicle is loaded extremely heavily. A after fire can also be caused by a sticky or worn valve. A faulty ignition switch can also contribute but a lot depends on what type of switch it is.

08-01-2020, 10:12 AM	#19
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: 1930 Sport Coupe 11 MPG, backfire when turned off Some folks refer to an after fire as a backfire. The exhaust should be mentioned if the backfire term is used or there can be a misunderstanding. The actual backfire through the throat of the intake manifold sounds more like a hickup so this leads to the confusion. The actual backfire is a sign of a lean condition under any form of load. 11-MPG is indicating a rich condition unless the vehicle is loaded extremely heavily. A after fire can also be caused by a sticky or worn valve. A faulty ignition switch can also contribute but a lot depends on what type of switch it is.