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Riddle me this... (Blocked air filter!)

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So, as the fuel mixed with the air passing through the carb is directly relative to the amount of air passing through (venturi effect producing high speed / negative pressure as it passes through the smaller section). How does a blocked air filter, that restricts air flow, produce a rich condition?

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Higher vaccum signal pulling more fuel thru the circuits?

 

Say you partialy block a vaccum cleaner's nozzle,

the total air flow may drop but the air velocity increases significantely.

The engine still has the same displacement despite a blocked filter.

Edited by mlatour

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Velocity is not vacuum.

 

Vacuum is pressue.

 

You have left out the liquid, and the second orifice, from your vacuum cleaner example.

The motor pulls from two locations: the carb circuits and the carbs intake stack.

 

As you increase the rpms of the motor, you increase both vacuum and velocity.

 

The Vacuum over the emulstion tube from the motor will not change dramatically with a dirty filter. It will pull up the same amount of fuel. But the amount of air entering the intake will decrease.

 

The A/F ratio is primarly air. A 1% change in air from the intake side of the carb is a larger volume than a 1% change in emulsified fuel from the carb.

Edited by KRANNIE

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Thanks for the explanation,

The 'normal' air-to-fuel ratio is around 14:1 to 15:1 if I remember correctly.

 

Had a nice Quadrajet carburator book a while back that explained all these principals, unfortunately I seem to have lost it over the years.

Edited by mlatour

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Thanks for the explanation,

The 'normal' air-to-fuel ratio is around 14:1 to 15:1 if I remember correctly.

 

Had a nice Quadrajet carburator book a while back that explained all these principals, unfortunately I seem to have lost it over the years.

 

Yeah, the thing is, there is so much air in an A/F ratio, that a small percentage change in air flow on the intake side alters the ratio quickly.

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