Will a 4af carburetor fit on a 3ac engine

[Als85tercel]

I found a cheap carb for a 4af and I was wondering if I should buy it for my Tercel or if it would be too difficult to install?

[dlb]

I don't remember anyone trying this before so you might be a pioneer on this one. I personally think it would be too much messing around because you would have to compare the vacuum hoses for the 3ac and 4af engines and figure out how to make it work on the 3ac. You'd have to do the same with the fuel cut-off solenoids and whatever other electronics are on your particular emissions package.

In short, you probably could make it work but it would take a lot of messing around.

[Als85tercel]

Hmm. What if I didn't care about the emissions stuff?

[dlb]

The emissions stuff is crucial to smooth, normal running. If you were to disconnect all the vacuum stuff on your 3a carb, it would barely run, if at all, so I think it would be similar with the 4af. But I'm just guessing here, I don't know what features the 4af carb has and how they match up with the 3ac's so who knows, maybe the swap will be pretty easy.

[Als85tercel]

I guess I've always wondered how much emissions stuff could just be capped off and deleted

[irowiki]

Let's put it this way, my first Tercel was a 1981 that the previous owner removed and capped off every emission device, and it ran like utter crap.

I swapped a proper carburetor with everything in tact and it ran so much better.

The biggest thing you can delete is the EGR.

[Petros]

that is a completely different engine design, different size, different cam timing, almost twice the HP output, etc. the throttle plate is likely bigger, so it could produce more power if you can work out the various systems on it (that were not designed for the 3a 8-valve engine). You would also have to find a source of different size jets, vents, emulation tubes, etc. I would not attempt it, likely not worth the effort. it had different emissions system on it as well, not suited to the 3a engine.

If you worked though how each of the emissions system works on both engines, and either adapted it or figured out a by pass to make it work, you might get it to run. but likely you will not be happy with the results.