Early aluminium ignition box

by joe turner in 912 / 914 Technical Questions 6 years ago

I have a very early 912 which has a remote aluminium box containing all the ignition system components. Although it runs well at the moment , I do worry that it will be the death of the engine should it malfunction.
Can these boxes be repaired as the components are accessible unlike the modern potted version?
Failing this, can it be replaced with modern modules?
Thanks for your help.

Re: Early aluminium ignition box

by Rob Seaton » 6 years ago

Rob Seaton

3 1.32k 240

It is unlikely to have an outright failure. More likely is some annoying high mag drops and if you take it apart you better label every connection really well as the horse trailer connectors are easy to miss-connect.
The biggest issue with the alum box was grounding (so many dissimilar metals). We always drilled a hole through the box, insert a grommet, and ran a good sized ground strap from the coil bracket to a good airframe ground. That solved most problems.
The secondary ignition wires can be replaced with the new type (with the new spark plug caps) but the clamp has to be modified to fit the larger diameter. This is a nice upgrade.
The modules can be replaced with new 965446 (but only do so if they have failed).
The P-lead capacitors can be removed and replaced with shielded wire.
The box can be eliminated and the ignition pack moved to the top of the engine. you would need to do some fabrication of brackets.

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Re: Early aluminium ignition box

by joe turner » 6 years ago

joe turner

6 10 21

Rob.
Thank you for your comprehensive reply. You've sorted every point and reassured me that the death of the box is not necessarily the end of the engine.
The small capacitors ( 0.05uf) have been removed after one burnt out and shielded wire to the switches is fitted.
I shall have a look inside the box and see if fitting a good earth to the coil bracket is within my skill level.
Am I correct to assume that the secondary ignition wires are there spark plug leads? If so, can I just make up leads using the correct cable or do Rotax do a replacement that allows for the extra length as my box is behind the firewall?
Joe

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Re: Early aluminium ignition box

by Rob Seaton » 6 years ago

Rob Seaton

3 1.32k 240

Hi Joe,
Correct; the secondary wire = spark plug lead. No kit available.
just make up the new spark plug leads using 865710 ignition wire, 860990 protection hose (this is mandatory) and 266248 or 265249 spark plug boots.
the wire screws onto a threaded prong in the coils and the spark plug caps.
You will need to order at least 5 meters of the wire and hose, depending on the location of your box.
remove the upper aluminum wire-clamp from the box (it will not fit the new wire). then trim out some of the lip from the lid so the wire is clamped but not damaging the wire. you can put some protective 3M rub tape or rubber
-run the secondary wire between the cylinder heads, just like the new engines. this saves some wire length and makes it much neater.

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Re: Early aluminium ignition box

by joe turner » 6 years ago

joe turner

6 10 21

Rob.
Thanks again for answering all questions- even the ones I hadn't thought of yet.
Joe

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Early aluminium ignition box

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