90 civic si hatch

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My daily driver for the last 7 years is a stock 90 civic 1.6 sohc w a/c hatchback. It's used oil since I've had it and I know it's tired. Now it needs a water pump / timing belt job.

I see the ads here for exchange engines. I'm wondering if that's a good way to go. I've worked on domestic stuff my whole career and have little experience other than simple service with these little scooters. You folks would probably overhaul this in your sleep.

I've no desire to build a racer. I'm into low maintenance and hi fuel mileage. Wasn't there a high fuel milage version? Did it really get better mileage? With the tired engine (comp 125-130) I get 35-38 but I'm usually pushing it on the freeway.

Maybe a trade for something that gets higher fuel milage?

If this was a domestic something i was familiar with I'd whip a cheap overhaul on it and drive the tires off.

I suspect the engine is a exchange unit. There are some handwritten numbers with Japanese with it on a sticker on the upper timing cover.

What would be the best way to go? Exchange engine? Remain head and rings & bearings?

Are there good remain heads on the net? Am I better off having this head overhauled in town? A friend told me if there not done right you get into shims or something.

Suggestions welcomed

Thanks, D
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Repair the problems you're having with it.Then give it a good tune up and add a few performance upgrades and move on.
It's probably cheaper to just replace the whole engine than to fix it with new rings/etc if that's whats going on. But, you might end up with a tired replacement too. Face it, these engines are old now!

do you know WHAT 1.6 sohc you have? there's many variants. Look for the engine code to the left of the exhaust manifold on the block by the tranny.
look for something like d16a stamped on it.

is your car an hf, dx, or si?

do you know if you are mpfi or dpfi?
I am guessing the trim is an Si (becuase of the thread name). But it could have a different motor in it now. These EF's are getting pretty old.

In comparison, the EF (88-91) is a little more tricky to swap other Honda motors in than a newer chassis. With that being said, there are fuel economic (OBD1) JDM D-series motors around that haven't been beat up too bad. It would take some work/mods to put a OBD1 set up into an EF. The main obstacle is the wiring. The existing engine harness needs to mate to the OBD1 motor and a jumper hanress for OBD0 harness to OBD1 ECU. But your trans will mate right up to it. No worries with axles, shift linkage, motor mounts or cable vs. hydro clutch.
I would consider two things (it would be one but you said you were worried about mpg so that's two) when making this decision. One is that putting a grand in parts and labor into a car that's worth about that is questionable. Two is that a newer Hx or Vx would probably get a LOT better mpg and still be pretty inexpensive if you went with a 92-95 or 96-2000. You could sell your current car to a tuner who will just pop a bigger motor into it so you wouldn't be out too much.