[Y-Blockhead]

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Originally Posted by Jim/TX/GA

Let me take these one at a time:

Benefit over a standard unit?: If you install an air filter and IF there is any restriction, it automatically compensates for the restriction. It's automatic at all throttle positions, all speeds.

Benefits too insignificant to notice?: On some cars, yes; on others, no. It really depends on how good the JETS are calibrated in the carb to begin with, and your skill at adjusting the GAV to compensate for the air filter if you do NOT use a balanced carb.

Many carbs have jets that are too large to begin with. Those cars run with the GAV fully closed and are still too rich. So add the air filter restriction and they are still too rich and you do not notice the difference. You can't adjust the GAV leaner to compensate for the air filter, because you already have the GAV closed.

This is what it sounds like Werner's Model A has. 20 liter/km is only 11.7 miles/gallon -- not good . These cars can do much better than that, if the carb is right. I regularly get 17-20 MPG with a balanced carb and an air filter.

Does high-flow air filter preclude the need? Technically, no. All air filters add some restriction. In practice, possibly. Do you care if the engine runs a bit richer than it needs to be? Gets slightly poorer gas mileage? If not, then don't worry about it. Install the air filter, adjust the GAV down a bit, and go!

Hope this helps!

.

Excellent write up Jim, as usual. Thanks for your time spent on a thorough explanation.

Werner indicated he is getting 16.25 mpg? (65/4) altho his numbers don't exactly jive?