Spark plug type

RichJohnson · Post by **RichJohnson** » Sat Nov 15, 2014 10:35 pm

I found some spark plugs in a box of stuff I bought and didn't know they were in there. This is the part number Ms35905-2 What are they for?

I looked at my M38a1 and I have MS35905-1 plugs in it, which is probably what was sold to me when I requested them years ago from a parts dealer.

I cant tell what is in my M37, they are so rusty crusty outside that its impossible to tell.

4x4M38 · Post by **4x4M38** » Sat Nov 15, 2014 10:56 pm

Could they be MS35909-1 and 2 instead of MS35905-1 and 2?

Looking at this M37 plug chart it might be just a warmer plug than the dash 1:
http://www.garbee.net/~cabell/SparkPlugData.htm

Brian

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RichJohnson · Post by **RichJohnson** » Sat Nov 15, 2014 11:17 pm

Yeah darn I knew I should have wrote it down to bring in to the laptop.
Its the 35909-2
That chart even has the same numbers AR 5s and 7s that were on these and the ones in my jeep.

I read the article and I now understand why you would go to a cooler plug with horsepower engine upgrades, but...

What would be a benefit for the military in a stock M38a1 or M37 to go to a warmer or cooler plug? IE why did the military have them? Operating Climate?

What is correct for the typical M38a1 and M37?

Post by **wesk** » Sun Nov 16, 2014 12:04 am

The correct plugs are listed in the service manuals for both trucks. If your truck starts using a wee bit of oil and fouls plugs often then you would switch to a hotter plug.

I have a plug chart posted in my photo album. The primary plug for the M38 & the M37 is the Autolite 2243. For the M38A1 the Auto-lite 2245

My M38 has 2243's in it as does my M37.