MF 135 sparkplug reach

kidrod72 · May 23, 2015

I have a '71 MF 135 with the Perkins AG3.152 engine. There are 2 different reach sparkplugs listed for this engine a 3/8" reach and a 3/4" reach plug. I have not been able to find out when (serial #'s ?) the 3/4" reach plug is used. There is no change in head or pistons for this engine that I have found. Any help would be appreciated.

ptfarmer · May 23, 2015

Pull a spark plug, you can tell real quick which one you need. The 3/8" reach is Autolite 295 (or other brand equivalent). The 3/4" reach is Autolite 4265 (or other brand equivalent). The plug gap is .025".

kidrod72 · May 23, 2015

I have the 3/8" plugs in it right now, and that's what it had in it when I got it. The guy I got it from was not mechanical at all though, so I want to make sure I have the right plugs in it. I can't find anything that states which engines use the 3/4" plugs

ptfarmer · May 23, 2015

The amount of threads in the plug hole "should" tell you which plugs you need (I couldn't find any info on the two different reach spark plugs for the same engine). If there is any doubt use the short reach. I've worked on a couple of different engines where people put long reach plugs in instead of the short reach plugs, it can get expensive!

kidrod72 · May 23, 2015

That was the only thing I could think of to do. I was going to run a dental pick,basically, over the threads and count them as I pulled it over the threads. I was just hoping someone had some literature about the different plugs. My local MF dealer doesn't know anymore about why or when the plug reach was changed either , and I haven't been able to find anything on it at all. Only that 2 different plug lengths are listed for it, one head and one set of pistons. I figured I would be safe with the shorter plugs, but was worried about not having the spark where it needed to be.

MF 135 sparkplug reach

kidrod72

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ptfarmer

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kidrod72

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ptfarmer

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kidrod72

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