(800) 853-2651
SHOP NOW

Onan Twin with Two coils

O

olddog

Well-known Member
John T & others....
older opposed twin Cylinder Onan flathead uses a
Wasted Spark ignition, where both cylinders are fired at the
same time, the cylinder that's on the intake stroke being wasted.
They used a double (unique Hi $$$) coil.
Question is... can a single set of points be made to saturate 2 single
(nominal 12V) coils simultaneously? Maybe with two condensors?
PS: Onan points are on the camshaft, so have twice as long to remain closed
per revolution as compared to a crankshaft driven set of points.
 
I tried exactly what you want to do, wasnt happy with results. It works, but... I gave up and bought a coil from CNH for 138$ , later saw them on line for under $30
 
Yes, these engines will run with 2 seperate coils. The only problem is that the spark is not quite as hot to each cylinder with this set up. I have seen them run set up this way for years though. The OEM coils is made so that one spark plug fires + to- and the other fires - to +. This is not anything that would casue problems if done with 2 coils. If you have to buy 2 regular coils it would be almost as cheap to order one Onan coil from Amazon to use. Gene Davis Tennille, Ga.
 
YES Ive seen and used myself TWO COILS and YES it worked...........YES a single set of points can provide current for two coils

HOWEVER

A limiting factor as far as the points are concerned IS TOO MUCH CURRENT WILL SHORTEN THE LIFE OF THE POJNTS

If you powered up two coils conducting at the same time you could (subject to the coils LV primary resistance) cause the points to conduct excess current and burn them prematurely

Its best if the plug gaps current arc goes from a Hotter (electrode tip) to a Cooler (plugs ground strap) although sure it still work at either polarity

While Ive done it BOTH ways and it works, my advice is the correct single coil and waste spark system

John T
 
Would an early Harley coil work?

Same principle, single coil firing 2 secondaries at the same time.

Not too expensive aftermarket, but who knows about the quality.
 

You can buy replacement coils for Onans in the $30 range on Amazon and fleabay, a MUCH better plan than reinventing the wheel, buying TWO coils and doubling the current through your breaker points.
 
Yes they will work. As will the coils used by a lot of GM v6s with wasted spark systems, 3 coils two terminals each, but will require a resistor to limit current.
 
You must log in or register to reply here.

Similar threads

J
How to wire ignition (not a tractor)
Replies
18
Views
854
SparepartsTN
S
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top