Well, I've certainly learned that converting from 150 to 160 turns out to be somewhat more than just bolting on new cylinders, especially when starting with a narrow deck 150. Thanks to help from numerous members here I
think I have it figured out, with a reasonable path to accomplishing it. I'll be talking details with my IA (who has very graciously agreed to supervise my work on the project) tomorrow to see if he concurs with my conclusions, and then take action. HOURS of research were involved for this amateur!
Many thanks to all of you who have helped me with this!
FWIW, here is my research summary for converting A2B narrow deck 150 HP to B2B wide deck 160 HP, given that an A2B wide deck case is available.
No guarantees of this being perfectly accurate. I am not an A&P and this is not advice. It's the best I have to date, so thought I'd share as a preliminary report.
- Lycon STC to upgrade horsepower requires wide deck for the 160 engine.
- Crosswinds STC (160 HP in PA-12) specifies B2B with round airbox and rear-mount oil cooler. Airbox and rear-mount oil cooler can be deviated by IA discretion (I would want to deviate). Charly sez round airbox gives 10 - 20 additional RPM.
- Peterson STC for Mogas requires 91 octane (premium) auto fuel.
- AD 98-02-08 for 160 HP O-320 requires crankshaft internal inspection IAW Lycoming SB 505B. The overhaul yellow tag for my existing crankshaft specifies SB 505 complied with. However crank flange is not stamped PID to indicate the internal coating that terminates the AD. So appears to need visual internal inspection and termination of the AD by applying Urethabond 104. The SB specifies all O-320 engines, while the AD specifies only 160 HP versions. Seems like a good idea to re-inspect regardless?
- Lycoming Service Instruction 1304J specifies to mark data plate with a “C” as a suffix to the serial number, to indicate modification of the engine model designation.
- Lycon says there are some accessory case gear differences between narrow deck and wide deck. The differences weren’t specified on the phone. From the parts manual it looks like just the crankshaft idler gear and bushing.
- Per Lycoming parts manual (WCF = wide deck, and STD = narrow deck in parts book nomenclature):
- Case same for A2B WCF and B2B WCF
- Crankshaft same for A2B STD and B2B WCF (AD 98-02-08 applies)
- Crankshaft main bearings DIFFERENT for A2B STD and B2B WCF (fig 1-2)
- Crankshaft idler gear and bushing DIFFERENT for A2B STD and B2B WCF (fig 1-7)
- Camshaft same for A2B STD and B2B WCF
- Lifters same for A2B STD and B2B WCF
- Pushrods appear to be the same for all O-320. Different P/N’s available, different lengths? Might need some DIFFERENT length pushrods. Need to consult overhaul manual for determination. Shorter rods will result from milled case halves.
- Connecting rods and crankpin bearings same for A2B STD and B2B WCF
- Sump same for A2B STD, A2B WCF. and B2B WCF
- Piston pins appear to be “heavy” for low compression A models and “regular” for other models. Probably DIFFERENT fig 3-1
- Piston pin plug - no mention of what to use with nickel plated cylinders. Probably DIFFERENT Fig 3-1
- Accessory housing same for A2B STD and B2B WCF
- Carburetor same for A2B STD and B2B WCF Charly Center says carb may need re-jetting to be a little richer.
- Magnetos same for A2B STD and B2B WCF
- Dipstick same for A2B STD and B2B WCF