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74 620 AIR FILTER


74DAT620

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looking to clean up the engine bay a little. I want to get rid of the huge blue air filter housing and possibly the egr system. All I can find are the old photobucket pictures which do not load fully. Does anyone have a diagram of which hose/lines to plug which ones are necessary. Mainly for the air filter. Thank you

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The stock air filter has what's called the ATC or automatic temperature control. When connected and working properly it mixes air warmed by the hot exhaust with cold air during warm up and on cold days. It has a vacuum flap gate that is controlled by a thermostat in the filter housing and regulates the engine air to around 100F. Other than the summer the engine thinks it's warm out and runs the same as summer year round. You get better mileage when it's cold because the gas more fully evaporates in warm air. If the outside air temperatures drops below 38 and it's raining, foggy or just damp out, you can suffer carb icing. This is because gas absorbs heat to evaporate and can cool the carb below freezing. Damp air forms frost all over the venturi and the engine starves for gas. The symptom is lack of power and pushing the gas pedal more and more to the floor. If you pull over it will usually idle but you have trouble driving off. If you wait the frost melts and away you go for another few blocks and it repeats. If you go this route and have these problems next winter at least you know what's wrong. I wouldn't throw the air filter away.

 

It's easier to just pull the hose off the EGR to disable it than remove and seal the pipe from the exhaust manifold and take the EGR off and make a block off plate. Many just can't be bothered to drill and tap a spot for the PCV valve and that's a shame because this little device increase the life of your engine by twice by keeping the oil clean. There is also the risk of the block off plate leaking, and they all look ghetto made. The EGR only operates at part throttle so performance remains unaffected. There are no magical gains from all this work and everything to lose from it.

 

JmOnTu1.jpg

 

This is my intake with the EGR manifold unbolted and removed...

CFOY8X4.jpg

 

 

This is the same manifold with some grinding and JB weld. I drilled and tapped one of the holes so I could keep the PCV valve.

w6EMG9j.jpg

 

From a distance it looks like an earlier L16 intake but it's really a '79 L20B intake with the larger runner diameters. Now that's de-smogged!

 

izWsyiW.jpg

 

 

 

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