Free Flight
Old-Timers
Clarence Haught
BUYING a used engine Many modelers want to power their Old-Timer models with an original ignition engine. Although the number of such engines is diminishing, there are still good engines available if you know where to look.
Sources for used engines
- Other modelers: long-time enthusiasts often have extras.
- Collectors' get-togethers: these sometimes accompany larger Old-Timer contests. Collectors often prefer mint-condition examples but occasionally have good "runners" for sale.
- Classified ads: Sunday papers or free-trading newsprint journals can uncover many engines.
- Bulletin boards and online ads: expect to find many glow engines, but you might get lucky with ignition engines.
If you plan to risk crashes, flyaways, and other mishaps, avoid using the most valuable collectible engines in your models.
Price and trade
Price depends on many factors and often comes down to negotiation and what you're willing to pay. Prices vary regionally. Trades are common—I've had good luck trading radio equipment and models for old ignition engines.
Inspecting a prospective purchase
Most purchases are "as is" and test-running an engine is usually not feasible, but a careful inspection can tell you a lot.
- Check for missing parts
- Needle valves, screws, drive washers, timers (especially on engines converted to glow plug use).
- Missing parts increase cost and may be hard to find.
- Look for crash damage
- Broken motor mount lugs, cracked crankcases, broken cooling fins.
- Some damage may be repairable, but severe cracks can be unrepairable.
- Compression and internal condition
- Install a propeller and snug a spark or glow plug into the cylinder to rotate the crankshaft under compression.
- Compression should be good and snappy. A little oil helps with the check.
- Stiffness might be gummed oil—or it could indicate a bent crankshaft or scored piston.
- Observe the exhaust stack while rotating after compression for bubbles or a wheezing sound indicating leakage past the piston.
- Bad compression can often be restored unless caused by a leaking head gasket; if compression is poor, consider passing on the engine.
- Check crankshaft/bearing fit and crankcase compression
- Grasp the engine and try to wobble the main bearing using the propeller. Excess play indicates wear and potential crankcase compression leakage.
- Crankcase compression (created on the piston’s downward stroke) forces the fuel/air mixture through the bypass into the cylinder to be compressed on the upstroke—leaks here produce poor running even if cylinder compression seems normal.
- Check for crankshaft runout by measuring propeller blade distance from the cylinder head with blades vertical and horizontal. Bent crankshafts are usually unsafe to straighten.
- Check connecting rod wear
- Feel for crankshaft play (wobble) with the piston at top dead center. You can feel the mechanism "going past center" and estimate internal wear. New engines show some of this; excessive play suggests a high-time or poorly fitted engine.
- Inspect gaskets and seals
- Check cylinder head, cylinder-to-crankcase joint, and back cover plate for leaks. These are usually repairable with new gaskets made from gasket stock obtainable at automotive parts suppliers.
Anecdote: I once had a Medwell .49 that leaked at the cylinder-to-crankcase joint; locating and repairing the problem restored excellent performance.
Engine sizes and availability
Most engines available today are the larger sizes, with .60 cu. in. displacement being the most common. Smaller engines were produced in quantity, but fewer have survived. Larger engines were popular because they could fly bigger models that carried the heavy ignition systems and batteries available at the time. Early batteries (D cells, Pelletite types) were marginal and often only lasted a single flight.
Good luck on your search for good ignition engines.
Clarence Haught 3226 Honeysuckle Dr. Coeur d'Alene, ID 83814
Transcribed from original scans by AI. Minor OCR errors may remain.
