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For the coil and control module, I used the GM HEI system with coil IC107 and control module TP45 (NAPA part numbers).

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I mounted the two coils and control modules on the firewall, close to the MSD coil selector.

Time to start! (May 2003)

I thought a little battery would suffice.  But it did not... I tried again boosting from my Ford Windstar and nothing...   I knew about a polarity problem with the pickup coils, but from what I read, that does not prevent the engine from starting.  

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So, I checked to see what was going on and I found that the coils would generate absolutely no spark.  Following my mentor's advise, I disconnected a TP-45 module and its coil and I connected my old Nippodenso ignition instead.   The engine started immediately!  So, I knew the problem was with the ignition.  After a series of email exchange with Paul Messinger, Dan Horton and others who lived through the same situation as me (such as Todd McLauchlin), I was convinced to try reversing the pickup wires.  

I didn't think about doing this before because I was so convinced that the polarities were right.  On my Nippodenso control module, the casing is marked for positive and negative.  The positive wire is red.  (the reader interested in understanding the background of this situation should read Contact issue no. 43 or Paul Messinger's Dual-Dizzy conversion manual)  Moreover, I confirmed the polarities of the pickups with my oscilloscope.

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Reversing the pickup coil polarity ended up working (partly).  The engine is pretty hard to start when compared with the Nippodenso ignition setup.  I suspect that the TP-45 module is less sensitive to the pickup signal than the Nippodenso module.  But at least, the engine runs smoothly on both ignitions.  The red and positive wire is now connected to the "G" terminal of the TP-45 (instead of to the "W" terminal).

I worked several days trying to improve this starting problem with the GM modules.  I tried replacing a module with a Standard LX-301 (equivalent to the Napa TP-45) and I got the same result.  I tried readjusting the air gap in the distributor and got slight improvement, but not enough.  One of the support for the ND pickup was not straight.  I corrected that while adjusting the air gap.

In the end (that was in July 2004), I abandoned this setup as I think that the starter/flywheel combination I have just does not rotate the crank shaft fast enough for the dizzy to generate a strong-enough signal.  A friend using a different conversion (the flywheel on the upper pulley of his belt-drive) has no problem starting his engine with that ignition system.

Not ignition related, but while we talk technology...

I discovered that my Engine Instrument System from Grand-Rapid Technology has a serial port for data transfer.  I called the company to ask about this and they e-mailed me the data recording software, which I installed in an old laptop that I normally use for planning my cave and mixed gas dives.  It is now a dual-purpose laptop!!  Once the data is transferred, I can load it into Microsoft Excel and I can create any graph I want trending RPM, CHTs, EGTs, Oil Pressure, Oil Temperature, Fuel Pressure, Coolant Temperature, Outside Air Temp and more. 

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April 25, 2004 update: Last week, I had a discussion with Tony Colucci (another CH601 builder and flyer); he uses the Nippodenso/GM HEI setup.  Tony uses the same engine/redrive combination as I do.... so I retested my distributor with the GM HEI on a workbench.  The combination requires less than 270 engine rpm to show good consistent sparks.  At 200 rpm, it will show sparks, but inconsistent.

So I went to Tony's place and found that his engines starter turns the engine at more than 320 rpm!  I went to my airport to check my own engine and it starts at more than 340 rpm!!  So I was puzzled... why this thing did not work last summer?  Would it work now?  I decided to re-install it and it worked!  I'm happy to use this setup now. 

A note on testing rpm...  What I did on the workbench was to attach the dizzy gear to my battery powered hand drill with duck tape, connect everything and use the timing strobe light to sense the pulses on the spark plug wire (one spark plug connected directly to the coil).  My timing light has a LCD display that shows RPM on a 4 cyl engine.  So, I divide the result by 4 and multiply by 2 (engine turns twice as fast as the dizzy).  On the plane, I attach one spark plug directly to the coil and use the timing light (this procedure prevents the engine from starting).




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Michel Therrien, (c) 1999 - 2003.