Gregmarlow

Gregmarlow

Well Known Member
Okay, sorry in advance for the dumb question - I'm a turbine guy.

Anyway, I just received my new IO-320-X from Barrett, and pre-reading some of the material they provided about pre-oiling the engine I came across the idea of removing the top spark plugs in each cyllinder. Why only the top ones? I'm guessing that with the top ones removed, combustion in the engine is impossible, even with the bottom ones in.

Thanks for the enlightenment,
 
You could remove either the top or bottom plugs......the tops are most likely the easiest to remove. This reduces the load on the "dry" crankshaft when the engine is turned because of the lack of compression. It also allows the engine to be turned more easily and faster if you use the starter to build the oil pressure.
 
With the top plug removed you have to be EXTREMELY vigilant that no foreign object can fall into the cylinder. Obviously not much chance of that happening with the bottom plug removed.
 
Bottom plugs are better for the reason mentioned above and also because any excess oil in the cylinder will drain out as you crank, preventing fouling when you first try to start.
 
gasman said:
Just lay a shop rag over the open holes.........
Click to expand...

Don't forget that during the power stroke all valves are closed. If the engine is being spun by the starter, this can produce a pretty strong suck on those rags. Just make sure they're too big to get pulled in.
 
Kingsport

Greg,

I live in "The Model City" as well. Where is your project, have you move it to an airport yet? I'd love to see it sometime, if you don't mind. Although I haven't built a plane yet, I am an A&P and avionics tech; let me know if I can be of any assistance.

Freddy
423-276-4773
 
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