What puts the "C" in 4A-C?

Every time I see an answer for what the "C" means, I see a different response. So far:

-Head design
-California spec
-Carburetted

But if the head between a 4A and 4A-C is otherwise the same, how can it be the head design? Sources indicate that DOHC heads are specified by a suffix F or G, and SOHC heads have no suffix at all.

And how can a 4A-C be available in a Federal, Canadian, or California specification if the C means California-spec?

And the C can't mean carburetted if the 4A is also a carburettor-equipped engine.

The answer comes from an older car - the owner's manual for the 3A-C-equipped Tercel states, very simply, that the C means it is equipped with a Catalytic converter.

We know that U means an engine has Japanese-spec emissions control systems, ergo, the C simply means the engine is equipped with a non-Japanese cat.

California spec emissions.

Once again - it can't be a federal California spec or Canadian California spec or California California spec engine. My 4A-Cs are all non-California specification engines, but they're still 4A-Cs. The Tercel handbook states that a 'C' simply means it's equipped with a Catalytic converter. Some might associate California with the first use of Catalytic converters, but this is slightly erroneous. While the first laws regarding tailpipe emissions were passed in California (1966, Federal standards followed in 1968), catalytic converters first appeared on vehicles in response to the EPA's 1975 emissions standards, which were impossible to meet by engine detuning without seriously crippling engine performance.

So, for C to mean California specification would require:

-All three emissions packages to be California-compliant (they're not)
-The association, by the good folks at Toyota, of Catalytic converters with California (possible)

We also know that the difference between a Federal and California emissions package (as stated in numerous Toyota materials, from the AE82 FSM to the 1981 Tercel driver's handbook) is more than the cat, which the vehicle would have had anyway. Armed with this knowledge, we can conclude that having a Catalytic converter, even to Toyota, is not synonymous with California specifications.



Since the Tercel's manual states that the C means it has a Catalytic converter, we can take the statement at face value, and conclude that this is not any kind of association with the state of California, and that the C in 3A-C means "Non-Japanese (U) type Catalytic converter-equipped." I doubt that it means any different on the 4A-C.

So half of you have 4As and not 4A-Cs... dirty boys!

Great info and awesome thread to read through.

Just wanted to say it cannot be California as in the Philippines and Australia we/they got 4AC AE71s, AE82 and SR5 AE86. Unless their emissions specs are the same as California. I know in the islands we have days where certain digit license plates can't drive on the highway to Manila or you'll get a nice infraction.

Same thing goes for the 4K-C Starlet motor I have a Canada spec KP.

Good points on it not being carbureted, or wouldn't Toyota's 22R be a 22R-C, although there is a 18R-C.

Why doesnt the 4a-ge have a c in it even though its got a cat the c basically means its carb'd. theres also a efi version of the sohc engine in japan with the designation of 4a-geu. Ive done research because i was planning on using its intake manifold for a efi conversion.