Ask Paul: Upgrading to a wide deck engine

Q: I read your article from the Oct .7, 2009, issue of General Aviation News on Wide Deck vs. Narrow Deck Lycomings with great interest. I am trying to figure out one detail that I think your article answers, but I just want to make sure.

I have a 1960 PA-22 Tripacer that originally came with a 150-hp O-320-A2B ND engine. It is ready for a major overhaul, and my IA recommends that I upgrade to a WD O-320-B2B engine.

I’ve had a tough time finding rebuildable cores, but have found yellow-tagged WD cases. I would like to buy one of these WD cases and build up a new engine for my plane, replacing parts as necessary based on inspections, or as required for the WD. The top end cylinder/piston/valve assemblies will be all new, of course.

The thing I’m still wondering about is how the paperwork for this plan would be handled. The parts vendor selling me the case says that all that is required would be a logbook notation and to stamp the “A” on to the end of the serial number. However, the data plate on the engine would still read “O-320-A2B” as no new data plate would come with the replacement crankcase.

Wondering if you could shed some light on the paperwork part of this project.

KELLY McARTHUR

A: Kelly, since you have, what I assume, is a normal running O-320-A2B in your 1960 PA-22 Tri-Pacer, why not go with what ya got?

Now this, of course, depends on the condition of your crankcase at the time of overhaul. If the crankcase is certifiable after inspection and shows no cracks, my opinion would be to use it and go ahead and put it back in service.

While your IA may have a valid point, I think his route may cost you more money for something you may not really need. You’ve already learned that rebuildable cores are very scarce. If your basic engine is still in certifiable condition, but the cylinders are all used up, then I’d consider using the original components, such as the crankcase, oil sump, and accessory housing and put your money in a set of brand new factory cylinder kits. These kits provide all of the major components you need from the crankcase out and are factory new.

I guess the perception in the field is that since Lycoming no longer supports the Narrow Deck engines, it no longer manufactures any parts for these engines. The truth is, in fact, it does continue to manufacture factory new cylinders and cylinder kits.

The Lycoming cylinder kits have been extremely popular since they were introduced to the market several years ago. Many of the reputable field engine overhaul facilities choose these kits versus going through the overhaul process on cylinders removed from high-time engines.

It’s simply an economic thing. If you spend X man hours disassembling, cleaning, and inspecting the cylinders from a high-time engine, and then discover they are cracked or worn beyond limits, your only options are to send them out for chrome and weld. While this process has been used in the industry for many, many years, you are still left with over all cylinder material that has tons of hours on it.

The cost difference between going this route versus the factory new kits really isn’t that great when you consider what you end up with. I’m not blind to the fact that there are other sources for cylinders available, but in the long run, I believe it’s hard to beat factory new.

Let’s get back the IA’s recommendation about upgrading to an O-320-B2B. First of all, the B2B is rated at 160 hp, so if you go with that engine, it would have to be done under an FAA STC. You can research what STCs for that conversion might be available by going to the FAA website and looking for Piper PA-22 engine conversion STCs. I must disagree with what the vendor told you — it’s just not quite that simple.

I honestly believe that were you to have your present engine overhauled and brought up to factory new limits, when you fly it, you’re going to think you’ve got a 160-hp engine. You are probably so used to flying your old, high-time engine that you haven’t noticed the slight degradation in power over time. When you fly the aircraft following overhaul, you’ll be surprised in the difference. Just for the heck of it, I’d also have your tachometer calibrated while doing the overhaul. I’d be willing to make a small wager that it’s off.

Comments

  1. Gary Hockensmith says:

    Paul, I need some some help from you or your readers in finding details on an aircraft. Several years ago I saw an aircraft parked at an airport in Texas that bore a strong resemblance to a Beech T-34 mentor only it was a 4 place. As best I can recall it looked like a T-34 fuselage and tail (no it was not a navion). I could swear that at the time I was able to determine that it was in fact a derivative of the T-34. Was I dreaming or does such a Beechcraft exist. I cannot locate any info on this bird now. Would appreciate any help on the identity of this aircraft.
    Thanks,
    Gary

  2. Linda S. Berl says:

    I’ve had welded cylinders come apart in flight (catastrophic engine failure). I second the idea of new cylinders!

Speak Your Mind

*