Help on Lyc. 225 (R-680)

[Jeff Foley]

I need to converse with someone familiar with this engine. Having a
problem that is perplexing several of us. I get a normal 50 rpm drop
on the right mag, but get a 200 rpm drop on left. Have replaced left
distributor cap, rotor, high tension lead, checked all wires and
plugs....nothing helps. Replaced mag with overhauled unit...still no
luck....yet I can switch the high tension leads on the mag and the
left will run fine and the problem moves to the right. If I start it
and run it on the left mag only for a few seconds only....no.8
cylinder does not get hot at all, and no. 2 gets barely warm. If it
is a mechancial problem with either or both of those cylinders, why is
it only showing on the left mag position? We are getting ready to
check the compression to see if we are losing any...especially on
those two cyl. I flew the airplane a month ago and it was running
fine...then it sat in the hangar for about three weeks and this
problem appeared. This is driving me nuts and getting expensive.
About a grand so far on the o/h mag and dist. parts.

Thanks to anyone who can help

Jeff Foley

[Orval Fairbairn]

In article >,
(Jeff Foley) wrote:

> I need to converse with someone familiar with this engine. Having a
> problem that is perplexing several of us. I get a normal 50 rpm drop
> on the right mag, but get a 200 rpm drop on left. Have replaced left
> distributor cap, rotor, high tension lead, checked all wires and
> plugs....nothing helps. Replaced mag with overhauled unit...still no
> luck....yet I can switch the high tension leads on the mag and the
> left will run fine and the problem moves to the right. If I start it
> and run it on the left mag only for a few seconds only....no.8
> cylinder does not get hot at all, and no. 2 gets barely warm. If it
> is a mechancial problem with either or both of those cylinders, why is
> it only showing on the left mag position? We are getting ready to
> check the compression to see if we are losing any...especially on
> those two cyl. I flew the airplane a month ago and it was running
> fine...then it sat in the hangar for about three weeks and this
> problem appeared. This is driving me nuts and getting expensive.
> About a grand so far on the o/h mag and dist. parts.
>
> Thanks to anyone who can help
>
> Jeff Foley

Do your mags have the external "fingers" that insert into the mag? If
so, get a depth caliper and calculate the gap between the rotor and the
tip (electrode) of the finger.

I had this problem on the old SF-6 "lunchbox" mags and solved it by
taking a full set of fingers and drilling and tapping for #4-40 brass
screws, installed from the INSIDE of the finger (so they won't fall out)
and filing the ends so that the gap was around .010 in. The old gap was
about .060" and resulted in an ignition system that would not tolerate
any kind of dirt on the cigarette ends.

BTW, check the cigarette ends to make sure that they are CLEAN.

[Jeff Foley]

(Craig) wrote in message >...
> (Jeff Foley) wrote in message >...
>
> Check the plug lead for leakage and try changing out the plugs
> themselves. Since the problem moves when you change the leads from one
> mag to the other, the only two things that were common to both then,
> are the leads and the plugs.
>
> Hope this helps....
>
> Craig C.
>

The problem is solved!!!

Somewhere along the way...while fixing the original problem I removed
all of the plug wires from the Dist. cap. When reinstalling them in
the new cap I used the labels on the plug leads as a guide to insert
them in the proper holes on the Dist cap. Whoever labeled the leads
used a "6" where there should have been a "9" and vice versa....so you
can guess what happened from here. The No.s 2 and 8 cylinders were
firing.....but at the wrong time. After finally discovering the
problem and switching the two leads....viola!!! runs like a champ.
Compression checks good......annual is complete....time to fly!!!

[Craig]

>
> The problem is solved!!!
>
> Somewhere along the way...while fixing the original problem I removed
> all of the plug wires from the Dist. cap. When reinstalling them in
> the new cap I used the labels on the plug leads as a guide to insert
> them in the proper holes on the Dist cap. Whoever labeled the leads
> used a "6" where there should have been a "9" and vice versa....so you
> can guess what happened from here. The No.s 2 and 8 cylinders were
> firing.....but at the wrong time. After finally discovering the
> problem and switching the two leads....viola!!! runs like a champ.
> Compression checks good......annual is complete....time to fly!!!

Glad to hear that it's up and healed.

We had to finally hang a board up in the shop with the phrase:
"Numbers on the mags are firing sequence not cylinder sequence"
because most of the guys would forget on the Eismen mags and use the
mag numbers as cylinder numbers al-la the newer mags.

One trick on the numbering is to skip the number "9" and leave that
one blank or use a letter. That way you have no possible chance of
flipping it and #6

Craig C.