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RPM drop Problem

 
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dennisvh



Joined: 21 Aug 2006
Posts: 3

PostPosted: Mon Aug 21, 2006 6:35 pm    Post subject: RPM drop Problem Reply with quote

I have a 1946 Ercoupe with a 85 HP (started out as a 75HP) Continental engine with a 200 RPM drop on the right mag at run-up. Mechanics have 100% eliminated as the problem both mags, all plugs, P-leads, and switch system. Also, the engine ran perfectly for the last 25 hours after a new wiring harness was installed. The harness was checked out and all wires were fine. We do not know what to check next. I would appreciate any advice anyone can give us. Thanks. Dennis Hatfield Question

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Kellym



Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

PostPosted: Mon Aug 21, 2006 7:19 pm    Post subject: RPM drop Problem Reply with quote

Well, you don't mention the timing being checked.

dennisvh wrote:
Quote:


I have a 1946 Ercoupe with a 85 HP (started out as a 75HP) Continental engine with a 200 RPM drop on the right mag at run-up. Mechanics have 100% eliminated as the problem both mags, all plugs, P-leads, and switch system. Also, the engine ran perfectly for the last 25 hours after a new wiring harness was installed. The harness was checked out and all wires were fine. We do not know what to check next. I would appreciate any advice anyone can give us. Thanks. Dennis Hatfield [Question]



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altoq(at)cebridge.net
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PostPosted: Mon Aug 21, 2006 7:23 pm    Post subject: RPM drop Problem Reply with quote

Dennis,

The only thing left is timing. If the Mags have not been moved, the timing
might be off because the impulse coupling does not return to the stop or
because the point gaps are wrong. Point gaps change because of metal
transfer at the contacts indicating a condenser problem or the fiber block
that follows the point cam is worn away by a rusty cam.

Good Luck
John D.

DO NOT ARCHIVE

We do not know what to check next. I would appreciate any advice anyone
can give us.
Thanks.
Dennis Hatfield


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jindoguy(at)gmail.com
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PostPosted: Mon Aug 21, 2006 7:31 pm    Post subject: RPM drop Problem Reply with quote

You say that mechanics have 100% eliminated. What did they do to eliminate those items? It'll save a lot of guessing games if you tell us that.

On 8/21/06, Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:[quote] --> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)>

Well, you don't mention the timing being checked.

dennisvh wrote:
Quote:
--> AeroElectric-List message posted by: "dennisvh" < dennisvh(at)adelphia.net (dennisvh(at)adelphia.net)>

I have a 1946 Ercoupe with a 85 HP (started out as a 75HP) Continental engine with a 200 RPM drop on the right mag at run-up. Mechanics have 100% eliminated as the problem both mags, all plugs, P-leads, and switch system. Also, the engine ran perfectly for the last 25 hours after a new wiring harness was installed. The harness was checked out and all wires were fine. We do not know what to check next. I would appreciate any advice anyone can give us. Thanks. Dennis Hatfield [Question]
--

Rick Girard
"Ya'll drop on in"
takes on a whole new meaning
when you live at the airport. [quote][b]


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FLYaDIVE(at)aol.com
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PostPosted: Tue Aug 22, 2006 2:42 am    Post subject: RPM drop Problem Reply with quote

Dennis:

Here are a few things I would check:
~ Timing
~ Fuel - Have you been using AvGas? If so you may have some coking around the
exhaust valve(s).
~ Spark Plug - Bad plug, carbon or lead fouling, cracked porcelain (swap left
and right plugs. If the problem follows the plugs, then just search down the
bad plug.)
~ Harness - Check the length of the coil springs. Give them a slight pull to
stretch the length. Also check down into the plugs looking for carbon or
arcing. (I'm assuming you are using massive plugs?)
Plugs - While looking down, make sure the screw down there is tight.
Mags - You said you eliminated them as being the problem, but why and how?
Have you looked inside? What is the e-gap and condition of the coil? Does the
problem get worse with time and heat?

OK, that is all I can think about before I have my coffee. Let us know how
you make out.

Barry (McCoy)
"Chop'd Liver"

"Show them the first time, correct them the second time, kick them the third
time."
Yamashiada
=============================================
I have a 1946 Ercoupe with a 85 HP (started out as a 75HP) Continental engine
with a 200 RPM drop on the right mag at run-up. Mechanics have 100%
eliminated as the problem both mags, all plugs, P-leads, and switch system. Also, the
engine ran perfectly for the last 25 hours after a new wiring harness was
installed. The harness was checked out and all wires were fine. We do not know
what to check next. I would appreciate any advice anyone can give us.
Thanks. Dennis Hatfield


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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