REFLECTOR: Franklin Engine

Tue Feb 18 17:13:57 CST 2014

One more thing to consider is the spark plug.

In my Franklin, I have light speed ignition and run their recommended spark
plug.

It is DENSO X27GPR-U.

It is a long reach and available from your local Honda Motorcycle shop for
cheap.

                Part Number 98061-59626

The proper spark plug adaptor is available from Light Speed.

I run the timing at 0 to start and 32 degrees for full power - Cylinder
Temps OK.

wj

WJ Wilbeck

620-727-3596

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of John Dibble
Sent: Tuesday, February 18, 2014 11:25 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: It's been really quiet this week

On 2/18/2014 9:43 AM, Brian Michalk wrote:

Hmm, I am a proponent of reducing timing to lower CHT's, and have my mag and
EI set to 28BTDC, advancing to 32BTDC above 2600 RPM.  The book value is
28-32 degrees.

I will retard it some more and we'll see what happens.

On the EI, I am running NGK Iridium IX plugs, with a fairly shallow reach.
I don't have the exact rating available at the moment.

I am seeing conflicting data.  My gasket thermocouples are reading redline
temps on takeoff, but the bayonet thermocouples are reading cool.  Do you
know what could be causing this?

Are they on the same side of the cylinder?  There's typically a 100F
difference between the inlet and exit air sides.

On 2/18/2014 8:51 AM, John Dibble wrote:

On 2/17/2014 11:44 AM, Brian Michalk wrote:

I've been flight testing.  It's a slow process for me, since my engine
design while Franklin based, has EFI and EI.
I have been battling high CHT's even in the cooler weather, and am seeing
positive results as the engine breaks in.

Sorry for repeating myself, but I really think you need to reduce the timing
advance to 24-25 degrees.  My anecdotal experience has been that any
departure from the mag/massive electrode combination increases the
detonation tendency for the Franklin engine.  Further, multiple changes
compound the problem.  When I bought my plane it had one mag and one EI,
both using massive electrode plugs.  I experienced minor detonation symptoms
such as an occasional plug fouled with metal and an occasional high CHT.
When I switched to auto plugs for the EI, the symptoms worsened with more
frequent plug fouling, erosion of the electrode and an occasional engine
stumble right after takeoff, a real attention getter.  When I switched the
mag plugs to fine wire, the engine stumbling became more frequent and I had
to replace a cylinder and piston due to severe pitting.  I have eliminated
the symptoms by reducing the timing advance.  I manually increase the EI
advance once I'm above 9k for max power.  Maybe Mike W will comment also.

John

  _____  

 <http://www.avast.com/> 

This email is free from viruses and malware because avast! Antivirus
<http://www.avast.com/>  protection is active. 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20140218/ce568d51/attachment.html>