Starting a 220 Stearman

We periodically have starting troubles. Maintenance is being done by a good shop, but this one is the only round engine they deal with.

I think the mags are Scintilla SF-7. We cannot find a "shower of sparks" box or any equivalent. Engine is nearing its overhaul hours, but compression is mostly good. Fine wire plugs.

When it arrived it started like a Cub- fuel, ignition, start. I know that several times it has become recalcitrant - once all we did was replace a fairly good Concorde with a brand new XC Concorde, and it dramatically changed the starting (not the starter rotation speed, just the ignition). That led me to think there was a "shower of sparks" box somewhere.

Lately we have had to flood it, then crank WOT to start it, and last week even that failed. Mechanic was able to start it by seven shots of prime and hard idle on the throttle, but not without some grinding.

Putting new fine wires in it (owners have more bucks than me, although I put them in my Decathlon and changed its entire personality).

Any hints from folks with more W-670 experience than we have?

How old are the mags, do they ever get oiled? There’s a little cup with spring loaded cap on the rear of the mag (hard to see) to put 10 or so drops of engine oil in or they could burn out. I’d say the E-gap/dwell needs checking, super easy to do. There is no need for shower of sparks on a W670.

I had a W670 that would not start unless you used the accelerator pump while cranking. Two or Three quick full throw throttle pumps. Try that. (No priming).

It's been a long time and I threw away a lot of my old manuals (I regret this) during a clean out.
Do you have a manual for the VMN-7? Try here: https://theunfamousseries.com/bendix-scintilla-magneto-service-manual.html

As I recall some of those mags had a separate set of retarded points for starting and a separate booster coil input. Others had a spark advance/retard lever which rotated the point assembly for starting.

Check the color and size of the spark. This can be done just by removing a plug lead or the plugs and holding them against the cylinder while rotating the engine. A weak yellow spark could mean the points are not set properly which happens over time with the wearing of the points and/or the cam follower. Or the magnet may have loss some of it's magnetism.

From your description it sounds as though this has been gradually worsening over time. Try resetting the points to peak magnetic flux prior to "E" gap. This is the most often fix for a weakening spark.

AKjurnees said:

How old are the mags, do they ever get oiled? There’s a little cup with spring loaded cap on the rear of the mag (hard to see) to put 10 or so drops of engine oil in or they could burn out. I’d say the E-gap/dwell needs checking, super easy to do. There is no need for shower of sparks on a W670.

I had a W670 that would not start unless you used the accelerator pump while cranking. Two or Three quick full throw throttle pumps. Try that. (No priming).

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There’s two spots to oil. The forward one is really hard to see

Edit, here’s a manual for the mags on the 220 I maintain

https://hangar603.org/wp-content/uploads/2018/02/wacoownman-07-magnetomanualocr.pdf

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My 220 has a “starting vibrator” which I am told makes a big difference. Sort of like a shower of sparks system.

We had troubles starting a 220 Stearman. Turns out hand primer was not working …. Removed, new o-rings, reinstalled … easy as pie to start (when it got fuel!).

You get smarter at starting when you have to crank the inertia handle each time. Just easier to pull blade thru.

Glenn

The local aero museum had a 220 stearman with an inertia (wind-it-up) starter, what a PITA.
If it had been me, I woulda just propped it, but they screwed around with that crank every time.
About two years ago, the master rod failed and the airplane was pretty well totalled in the resulting forced landing.
So I guess they won't have to worry about starting it any more- not for a while anyways.

Cranking the handle was always a crowd pleaser.

Glenn

I owned a Fleet 16B with a 220 Continental on it. The Flaglor Hi Tow, serial number one. Built as an “Experimental “ in 1957 by Ken Flaglor. You could get away with that, then.

It had retard breaker/shower of sparks starter. There was an unmarked toggle switch on the panel that would disable the shower of sparks so you could avoid kick backs. Get it cranking then put the switch on. We usually left it on all the time since up till that point we didn’t know what it was.) One day somebody turned it off (remember, unmarked) and the airplane was hard to start so I assumed the shower of sparks was not working. I buzzed the whole circuit out and guess what, it came back to that switch. Turned it on and all good!

Bob, if you have shower of sparks there should be a high tension lead going into the center of one mag. In addition the shower of sparks should activate only when the starter button is pushed. I guess you could test it by disconnecting power to the starter and pushing the start button to see if that center lead sparks to ground. If you don’t have the center lead, disregard. True retard breakers don’t work that way. They use the retarded set of points when the started is engaged, I think. The 220 in my Fleet came off a UPF -7 and had the HT lead going into one mag.

This is a 30 year memory so I apologize in advance for any mistakes.

Rich

I was going to join the Stearman Society, but you guys are a wealth of information. Thanks! Is the "box" inside the starter?

bob turner said:

I was going to join the Stearman Society, but you guys are a wealth of information. Thanks! Is the "box" inside the starter?

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No, separate. Just activated by the starter switch. As Rich mentions, look for an extra high tension lead feeding the magneto and trace it back. You'll find the box if you have one.

With a good E-80 starter(yes they get slow means it needs overhaul), good battery, and points set correctly there’s no need for shower of sparks. I’ve gone through seven 670’s to TBO and not one had it.

bob turner said:

I was going to join the Stearman Society, but you guys are a wealth of information. Thanks! Is the "box" inside the starter?

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We had the same issue..... installed a booster coil on the firewall and wired it into the starter button...works perfect !!!

hotrod180 said:

The local aero museum had a 220 stearman....
About two years ago, the master rod failed.....

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That looks like the main crankshaft journal, I wonder what caused that!

The Master rod is actually located on the #1 cylinder (the top cylinder) which the rest of the connecting rods join to. Ingenious design.

AKjurnees said:

That looks like the main crankshaft journal, I wonder what caused that!

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Looks to me as though the rod journal (crank pin) has fractured and half the crankshaft is separated. No idea how common that failure mode is but wonder if there was an earlier prop strike. Whatever happened it's a nasty mess.

I thought the crankshaft / master rod assembly was collectively referred to as the master rod.
But yes, as you can see, the crankshaft itself was what failed.
This airplane belongs to the local aero museum-
it was a donation, so no knowledge (other than logbooks) about previous history.
It definitely had a prop strike this go-round!

hotrod180 said:

I thought the crankshaft / master rod assembly was collectively referred to as the master rod.

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I'm certainly no radial engine expert but, for my own education and amusement, I downloaded a couple of manuals for the Wright R-1820. These documents refer to "connecting rod assembly", "master rod", "crankshaft", and "crankshaft and rod assembly".

Different manufacturers may use different terminology but for any radial engine doesn't the master rod have to be separable from the crankshaft? If so, you would have a master rod, 2 parts of a crankshaft, and, when assembled, a crankshaft and rod assembly. Referring to this assembly as a master rod would seem inappropriate but perhaps not for some engines.

Each radial engine has a single crankshaft throw for each row of cylinders. There is one master rod for each crank throw.
This is a single piece master rod. This engine would have a two piece crankshaft in order install the master rod. The articulating rods are sometimes called link rods.



This two row engine has a two piece master rod on each crank throw.