Smog emissions testing 22R carbureted

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May 5, 2019
My1981 Toyota 4x4 pickup has always needed excessive adjusting to pass smog here in Idaho where 1980 and earlier are exempt. This years test was no exception except that no matter what I did to eliminate it my CO numbers were very high on the high rpm test. My engine is bone stock with OEM carb and all the vacuum lines. I was minutes away from pulling the carb for a rebuild and float level adjustment when I decided to pull the large (1”) smog house that comes from a diaphragm housing below the carb. I noticed that it connected to a metal housing bolted to the air cleaner housing. When I unbolted it I found a pleated filter inside that was completely clogged with sludge. This is what was making the engine run excessively rich. I spoke with factory Toyota mechanics who were unaware that this breather filter even existed (likely since mechanics who had worked on these engines in the day, have retired). My truck has excellent emissions numbers now. The breather filter is no longer in production so I bought a $4 lawnmower sponge filter which fit great in the breather housing. Just wanted to post this for those who haven’t or cannot switch to a Weber conversion due to state smog laws and may have a rich condition.


Nice job sleuthing the problem … and even better coming up with a workable solution.

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