14.) Carb heat box: The carburetor heat box is based on 4 type 321 stainless tangs tig-welded to the 321 stainless exhaust pipe on the left side. Thin 316 stainless ends of the box are bolted to the tangs with #4 stainless fasteners and an aluminum box spans the ends, bolted with a series of tiny #2 bolts and MS21042 jet engine nuts. Inside the box is an .050” dia. 17-4 PH stainless spring that has been precipitation hardened for toughness (to avoid heat embrittlement and work hardening). The spring is wrapped around the “wishbone” area of the exhaust pipe for maximum heat transfer to the induction air. The carburetor temp gauge typically shows an 8 degree centigrade increase when full carb. heat is applied. On the “hot” end of both the right and left exhaust pipes, special ¼’’ 302 /304 stainless exhaust flanges were machined replacing the standard 3/16’’ flanges. The original flanges tended to warp slightly at the exhaust ports, which permitted some leakage of exhaust gasses around the exhaust gaskets.
15.) Carb, Throttle, mixture linkages: The carburetor was completely overhauled according to Marvel Schebler manual procedures, including throttle shaft, butterfly and shaft bushings, jets and virtually all moving parts. The Marvel Shebler manual is included with the sale of this project. The mixture valve was electro polished for a micro-smooth surface allowing smooth rotation at the bottom of the bowl. All bolts are safety wired. A carburetor air-temp. thermocouple was mounted in the carb. All linkages and cables connecting to the carburetor are precisely aligned, and mounted rigidly on .060 plate aluminum. Return springs likewise are adjusted for adequate tension without overload. All movements were studied and very carefully set up for very smooth and friction free, full range operation. Many accidents have been caused by lack of careful, anticipatory attention to this area. The throttle return springs are redundant and are connected to a thick chromoly tang mounted to the vacuum pump pad. (All carb. linkage return springs need to be examined under magnification at annual inspection to assess wear at their ends due to unavoidable harmonic vibration).
above:
a. carb. air-temp thermocouple
b. .060 plate
(also note silicone RTV rubber between 2 throttle springs to dampen vibration).
16.) Oil Filter / oil filter adaptor: Practically all Continental 0-200’s rely only on the screen filter, and do not have an oil filter at all. Some have been modified with one of several systems available for a firewall-mounted filter. A very rare Continental spin-on oil filter adaptor for the 0-200 was located. (from engines shipped to Saudi Arabia for Cessna 150’s as primary trainers). It is similar to the oil filter adaptors on the larger Continentals, but shorter. This allows oil directly from the oil pump to be filtered before going on to the engine. Other firewall mounted-type filters do not do this. An oil filter makes it possible to go 50 hrs. between the oil changes. Aero Shell 15-50 partially synthetic motor oil has been used exclusively, and the engine is spotless on the inside.
above:
a. Continental oil filter adaptor
b. Oil temp. sender