Experts say that if you need to rebuild your
cylinders (cracks are frequently found between the
valve seats or emanating from a spark plug
hole)—don’t. Buy new instead. The oldest cylinders have only partial part numbers stamped on
the sides of their bases, adjacent the case. Newer
cylinders (part number 641917 and above) carry
the full part number. If you have all four “newer”
cylinders, you can use 28-degree before top dead
center timing; older cylinders are covered by an
airworthiness directive (AD) that restricts timing
to 24 degrees.
Some very old carburetors contained defective
two-piece venturis (and some were okay). If you
get the chance, look. Even if the two-piece venturi
has been no trouble for the past 40 years, you can
still get a few dollars off when you buy it. There
was an AD (93-18-03), but not all engines needed
to comply with it, or did.
Accessory houses love the O-200, and that’s
good news for us. Spin-on oil filter adapters, lightweight starters, alternators, Slick magnetos (all
included on the -D version), special exhaust systems, and electronic ignitions are all readily
available. Aviation hot rodders have developed
their own favorite intake modifications and
exhaust systems in both mild steel and stainless.