1966 Mustang thermactor filter

Steel Ride Mustangs

New Member
Feb 11, 2018
Tomball, TX
Hi All.... Just removed the thermactor smog filter canister... it is empty... Can someone please help identify the proper filter that should be inside this canister. I searched and no results...thanks for your help... can running the car without this filter damage the system1??
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I prefer to be called "Evil Genius"
Founding Member
Oct 10, 2001
Western Mass
Looks to be the exhaust air supply cleaner used in '66 and '67.
Ford used to make a service package for these, but I don't think you will find one anymore, which is probably why it had been gutted.
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New Member
Nov 27, 2006
When I restored mine years ago, I found the crumbling remains of the original foam filter inside. I took the filter canister with me down to the local motorcycle shop and purchased a new foam motorcycle air filter that fit. It's just there to prevent anything (bug, leaf, pebble, etc) from getting sucked in and clogging the thermactor exhaust air injector tubes. Get a foam filter as I believe a paper filter will likely be too restrictive.

Frankly, my heads were extensive reworked for improved performance - hardened seats, larger quality GT40 valves, ported, flowed and port matched to the intake and exhaust manifolds - and had the tubes shaved off flush with the inside wall of the exhaust port in the heads. So, all stock looking from the outside, but much improved flow inside.
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