Having owned a 81 corolla with a 3tc, i would suggest keeping the 3tc its already a good little motor n like everyone else is saying a 3tc will walk a 4age all day with a bigger carb, also parts for the 3tc are cheaper as well, plus personaly i think the 3tc sounds better n im shure there are quite a few people will agree with me on that one, look at some videos on youtube of 3tcs n you'll see why people love them so much