Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  

Spark Plug differences

Recommended Posts


Hey Everyone,

I've got a spark plug question maybe somebody can shed some light on. Currently at my shop I have 2 push mowers a 1978 Sears/Roper with a Tecumseh LAV35 and a 1997 Murray with a Tecumseh TVS90. The Tecumseh LAV35 calls for a Champion J8C and the TVS90 a J19LM. Both the LAV and TVS are exactly the same except the LAV is points and condenser and the TVS is solid state, is there any difference between the J8C and J19LM? And why would 2 engines that are identical take 2 different plugs? Also Champion's part finder is saying to use a J19LM in stuff that previously called for a J8. Is there any difference/advantage between the J19LM vs the J8C? Thanks

Share this post

Link to post
Share on other sites

Spark plugs are like "beauty is in the eyes of the beholder", which means everybody has their own opinion. I look at it this way, the engine builder wouldn't be using it if it wasn't a viable product.The gospel from Briggs:


Share this post

Link to post
Share on other sites

J-8 and J19LM are different in heat range only. The higher the number in Champion speak means a hotter burning plug. You can run an .030 gapped J19LM in either or both engines with no ill effects, you may even get faster starts due to the smaller electrode giving better spark intensity.

I use the Autolite rapid start plug iridium (258?) for a lot of engines as the last longer, don't foul out and are less than $4 here. You can use that in place of J19LM.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Who's Online (See full list)

    • Chris727
    • TommyK1
    • Paul M.Murphy
    • NateShedivy
    • Sovereignm88
    • Ronald Hribar
    • CarlH
    • PhanDad
    • tripleguy
    • simplewrench
    • MercerRec
  • Today's Birthdays

    1. Carchief
      (57 years old)
    2. Geoff
      (56 years old)
    3. mohrds
      (51 years old)
  • Recent Status Updates

    • SonOfCreepfeed


      Thinkin' about this old girl.

      · 2 replies
    • Dean McFadden

      Dean McFadden

      Good morning peeps! I’m always searching for helpful information with my AC collection. Hope to find out new information and pass on my own experience in restoration. Here are some pics of my babies. I’m still looking for front rims for the 410 so yesterday I put the 310 wheels on took it for a drive. Working pretty good but still needs some carb work. Gotta get the 310 running next. Have a great day!😁

      · 1 reply
  • Adverts