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AC45-R

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=12427
Printed Date: 31 Jan 2025 at 7:52pm
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Topic: AC45-R

Posted By: EPALLIS
Subject: AC45-R
Date Posted: 13 May 2010 at 10:33pm

I needed to get a set of spark plugs for my model B. Hard to find A-C plugs. Anyway finally found an AC 45-R plug. The clerk convinced me this was the same thing as the AC 45 plug. He said "R" stood for resistor which is all plugs these days. Is this information correct and is the AC 45 "R" plug fine to use in my model B? Going orange is going great. Thanks for any assistance in advance.

Replies:

Posted By: EPALLIS
Date Posted: 17 May 2010 at 9:31pm

Anyone, any thoughts if the AC-45 spark plug and the AC-45R are one of the same??

Thanks!

Posted By: Hubert (Ga)engine7
Date Posted: 17 May 2010 at 10:19pm

They are not the same. Is your B magneto or battery and coil ignition? The resistor plugs are not to be used with a magneto. Try Autolite 295's.

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Just an old country boy saved by the grace of God.

Posted By: EPALLIS
Date Posted: 17 May 2010 at 10:55pm

I have 2 model "B's". One has a magneto the other I converted over to A-C delco ignition. So, I can't use the A-C 45R spark plug with a magneto? Why is that? Thanks.

Posted By: everett048
Date Posted: 18 May 2010 at 1:33am

As mentioned above ac45R is a resistor plug no good on magnetos will slowly kill coil untill it will not start been there done that lesson learned.

Posted By: JC-WI
Date Posted: 18 May 2010 at 10:12am

EPALLIS, DO NOT USE 'R' (resistor) plugs on a magneto. Have reworked to many magnetoes that had R plugs or carbon cored wires attached to them.

Like Everette says, they kill a magneto. Coils were not wound for bigger gaps than what the tip of a sparkplug is set for basically.

Posted By: Steve in NJ
Date Posted: 18 May 2010 at 10:48am

Never use resistor plugs with a Magneto. A Magneto makes its own power, and resistor plugs and or wires disrupts the magnetic field in the Mag that produces the fire power it needs to light off the plugs. You can install the resistor wires or plugs in your Battery powered Ignition system (Distributor equipped) without a problem... HTH

mailto:Steve@B&B - Steve@B&B

Posted By: EPALLIS
Date Posted: 23 May 2010 at 9:58pm

I really appreciate all this information, I'll remember to never use an "R"resistor plug with a magneto. Good information for anyone. Thanks again!!!!!!!!!!!!!!!!!!