The earliest Honda Civics with the 1170cc engine suffer from terminal anemia; while the chassis is decent, the engine is not quite up to the task. Honda bumped the displacement of the Civic's engine to 1238cc in 1973 by increasing the bore to 72mm. In 1976, the Civic was blessed with a new head that offered significantly larger valves and a domed combustion chamber to match the new domed pistons. This popular big-valve head will bolt right onto the earlier Civics.
Another good trick is to use pistons from Honda's GL1000 motorcycle in any of the early Civic blocks with a 72mm bore. These pistons offered a substantial compression increase without a huge weight gain. With some minor clearance modifications, the crank from a 1980-'83 Civic 1300 can be installed in the early blocks. The additional 6mm of stroke that this crank yields turns the little Civic motor into a torque monster.
If you don't want to screw around with swapping parts, just grab an entire engine. The 1975-'79 Civic engine can be transplanted into an earlier car with a minimum of modifications (mostly mounting hardware).
If the four-speed blues have got you down, fear not. The five-speed transmission from the 1975-'79 Civics will bolt right onto any other 1973-'79 Civic. The hot five-speed is the one from the 1975 Civic Wagon, as it has good first through fourth gears with a nice fifth for cruising. The one problem with this swap is that you lose the great 4.93:1 final drive gear that the four-speed comes with. There's a solution to this dilemma: just get a final drive from a 1980 Civic 1300 five-speed. Coincidentally, this is also a 4.93.
The 1975-'79 Civics are longer and heavier than their predecessors, so they feature heavier springs. The front springs from these cars will fit any Civic from 1973 to 1979. Just cut to the desired length and pop 'em in. For the rear, use Civic 1200 front springs cut to the desired length.
For some real improvements, bolt Civic Wagon (1975-'79) steering knuckles onto the bottom of your Civic 1200 struts. This allows you to bolt on Accord front brake calipers, which are much stronger than the stock Civic units. With some work, the wagon's rear brakes can be adapted to the 1200 Civic. Early Accord front lower control arms also can be fitted to the 1200 Civic for an increase in track.
The early Civic also had the complete wiring harness in place for a tach and auxiliary gauges. Consequently, the gauge cluster from the Civic five-speed can be easily installed in the 1200.
The content of this page was scraped from http://www.grmotorsports.com/boneyard.html (no longer existing) from around 2000, and featured on drzoom's website until ~2012.
