Franklin / PZL Model 4A-235-B31

The Franklin / PZL 4A-235-B3 aircraft engine was developed to be a higher power replacement for the Continental A-65 through 0-200 engine line. As a result, the Franklin engine will fit directly to an 0-200 engine mount, the exhaust system and carburetor mounts in nearly the same location and the cowling will usually still fit. The 4A-235 weighs within a few pounds of an 0-200 when the engine are comparably equipped, yet it is rated at 125 HP.

Download this engines dimensions.

Engine Specifications

Model 4A-235-B31
FAA Type Certificate No E6EA
Rated Horsepower 125 / 116 @ 2800RPM *
Number of Cylinders 4
Displacement 235 Cu. inches
Bore 4.625 Inches
Stroke 3.5 Inches
Engine Weight (Dry - Without Accessories) 206 lbs.
TBO 1500 Hours
Magnetos, Slick Model 4392
Magnetos, Bendix S4RN - 20 / 21
Ignition Timing, BTC, Both Magnetos 32 degrees
Firing Order 1, 4, 2, 3
Spark Plugs 18mm
Fuel System:  
Carburetor: Marvel Schebler MA-3SPA
Fuel - Minimum Octane - Aviation 100/130
Wet Slump - Oil Capacity 6.6 Qts.
Oil Grade, Above 41 Degrees Ambient Air SAE 40
Oil Grade, Below 41 Degrees Ambient Air SAE 20
Valve Clearance:  
Valve Rocker Clearance With Lifters Bled Down And Engine Cold 0.0360 - 0.044 inch
Operating Limits:  
RPM - Maximum Limit 2800
RPM Idle 750-950
Cylinder Head Temp (Bayonet Thermocouple) 392F
Oil Temperature - Maximum Inlet 234F
Oil Pressure - Operating Range 50-80 PSI
Oil Pressure - Idle 25 PSI
Fuel Pressure (Carb. Inlet) 2.2 - 7.3 PSI

* - 125 HP SAE, 116 HP Metric

Check out these benefits of the 125 hp Franklin engine !

FAA Certified - Factory New

Direct Drive - no gear reduction box

Smooth running - low rpm power

Unmatched horsepower / torque ratio

Most Economical engine in its class

Built-in crankshaft torsion damper

Proven Reliability

254 lb-ft torque at 2800 rpm!


These are NEW FAA-certified aircraft engines, not a rebuild of a high time engine that has been subjected to years of unknown treatment. Because these engines are used in helicopters (6-cylinder model), where they are turned at 3200 RPM, they are under stressed in fixed-wing aircraft where they are operated at 2800 RPM.


The cylinders, bearings, valves, lifters, connecting rods, etc., are common throughout the engine line production, reducing cost and parts inventory problems. The cylinders have removable sleeves (cost only about $80 each!) that are field replaceable, the camshaft is on the bottom of the engine, and the oil pump is in the sump, so there is less chance of losing its prime and the resulting dry starts, especially in cold weather. There is a removable top cover on the crankcase so that the inside of the engine can be easily inspected. The exhaust ports have insulating sleeves to reduce cooling requirements and simplify installation of exhaust manifolds. Further, the engine can be easily adapted for inverted oil systems.


All Franklin / PZL engines have built in fluid damper on the crankshaft which makes then the smoothest aircraft engines of their size.

Copyright © 1998-2023 Franklin Aircraft Engines All rights reserved.