72jd 400 spark plug question

[Recoil]

Hey guys, i went to the tech pages to find a spark plug replacement for my 400. I was surprised at the fact that the 1972 400s are broken into three groups?! My serial number is in the first group but i cannot find any of those listed plugs in my local shop. Why are they different? Why does the last group of sleds take a standard br9es but mine takes a plug i can't seem to find? Can i use a br9es in my machine?

Recoil

[JD600]

The 400's used 3 different engines over their 6 year production run (340/4, 340/5, and 340/22 Reed) The reed engines had much different cylinder heads than the piston ported engines, thus the different reach spark plugs. I'm surprised that your local shop does not have a cross reference book, as they should be able to cross the old numbers even though they are no longer available. That being said, i believe you need BR9HS plugs, but i will need to consult the manual as my memory leads me astray sometimes.

DE

[Recoil]

So i take it that is just a shorter reach plug? Well i hope these old plugs hold up during my vintage run tomorrow! If you happen to find out please let me know. I would certainly appreciate it.

Recoil

[harleysportster]

Found this in the FAQ section.
http://www.jdsleds.com/community/viewto ... f=4&t=2077

[JD600]

Thanks Pat. I was looking for that last night, but i couldn't find it. As i recall, the heat range of the stock plugs falls somewhere in between a BR9 and a BR8, the BR8 being the hotter of the 2. Either one should work just fine.

DE

[400brian]

So i take it that is just a shorter reach plug? Well i hope these old plugs hold up during my vintage run tomorrow! If you happen to find out please let me know. I would certainly appreciate it.

Recoil

The 72 and 73s all take the short reach plugs. I have been running the B8s for the past seven years, so far that heat range seems to be working out OK.