The International Cessna^® 170 Association

My project plane is a 1953 170B. The engine has been majored with an STC Skytek starter designed for key start. Skytek provides a push button starter control. However, I would like to use an ignition switch with a start function instead of the push button. Per Skytek, the starter button switches an inrush of 20 amps followed by about 7 amps. I am concerned this may exceed the key switch capacity (but I have not been able to find the capacity rating of the start switch). Can I use a starter solonoid? Has anyone done this on a 337? I had thought about mounting it on the battery box somewhat like early model 172. Comments?

Yes, you may use a starter solenoid. In fact, that's what many key-start systems use.
There are two types of solenoid: Constant duty and intermittent duty. The intermittent duty is only used for starter circuits.
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Depending upon application, the constant duty may be used for either master solenoid or starter solenoid.
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You will also need to install a key-start ignition/magneto switch.
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I do not know of any STC for this modification, but it sounds like a minor alteration that should be satisfactorily addressed with a logbook entry and reference to FAR43.13(b).

Thanks for the response. I have a new Cessna starter solonoid that I can use. Steve.

Keep in mind that Continental engines generally are equipped with two impulse couplings and start on both mags. Some mag switches that incorperate a start position are desigined to ground one mag that is not equipped with an impulse when switched to the start position.