air filter size

[72Chall77Doba]

I'm in the process of having my 72 restored and they replaced the air filter with a much thinner one, in height.
How will this affect the engine in terms of performance and mpg. I used to get 7 mpg.
318 with a 4 bbl holley double pumper.

[PlumCraZRT]

Put a regular air filter on if you're concerned about it.  In theory it could hurt your performance and gas mileage, but probably not a whole lot.  Better question is why you have a double pumper on a 318?  That's hurting your mileage worse than any airfilter could.  Unless you have 4.51 gears and a tranny that slips more than a roller skater in a ball bearing factory, a 625 cfm vacuum secondary carb that is well tuned should put you more in the tune of 15 mpg.  Such a small motor shouldn't struggling to get 10+ mpg.  You're not driving everywhere in reverse are you?   

[Jacksboys]

7 mpg with a 318 

Unless this is a high rpm race motor, you should be at least in the teens

[Chryco Psycho]

lose the filter , it has to be restricting the flow
 as for the 7 MPG something is not right

[nivvy]

lose the filter , it has to be restricting the flow
 as for the 7 MPG something is not right

  Stock 440375/HP cars got 13mpg 

[HP2]

Several years ago, one of the magazines did air flow testing on various sized filters. I think the minimum size they used before power started falling off was a 14" round and 3" tall unit. Anything smaller than that hurt output, but i don't recall the amounts.

As far as power and mileage, give us some more specs onthe engine. You might have too big a cam and too big a carb with too low compression for you combo.