Forums Archive Index > Outdoor Power Equipment > spark plug

Author: launboy

Date: 20 Dec 2006 7:04 pm

Yes, I know me again, with more questions... :shock: :?
Ok, when I went to get some shear bolts the other day at Lowes I was looking at the snowthrowers, and I noticed that all of the Tecumseh 5.5 HP (smallest engine they had on a 2 stage) had RJ19LM spark plugs in them...
When I got my Snapper with a 4HP tecumseh, the spark plug wa a cj8, so thats what I replaced it with. I know that running the wrong spark plug can cause something to get to hot or not hot enough... :? :? (just read it in a book to :x ) so, my question is, do I keep the CJ8 in it or switch to the J19LM.

I also noticed that my mower and most other OPE that i have with 4 cycle engines have the J19LM in them so thats what makes me think I should change.

Thanks,
Adam


Author: sonofjabba

Date: 20 Dec 2006 7:34 pm

I personally Use Autolite plugs and I have seen both plugs in identicle engines. I think they used whatever was around. Most flat head OPE engine plugs are pretty interchangable. They only have 3 common sizes. The OHV engines however are a different story.
I use 458 Autolites in my Tecumsehs, and some of my briggs engines. They are the Champion CJ8 Equal.
Just remember the Gap is .030" for Tecumseh..


Author: launboy

Date: 20 Dec 2006 8:28 pm

Ok, thanks, I didn't think it would make too big of a difference since the one i have in there now is the equivalent of a CJ8, It's an E3 "with Diamond Fire Technology" Since I already bought the J19LM equivalent, I will just put it in the Lawnmower in the spring.


Author: newjerseybt

Date: 21 Dec 2006 9:09 am

Watch those sparkplugs!

I once handed my Champion Spark plug from my Arien's 11.5HP OHV Tecumseh SnowKing to a worker at Pep-Boys for replacement.

He came back with a plug and said "close enough".

Upon closer examination I noticed the tip extended much further than the old plug. I' ll bet if I installed it, the piston might have struck the electrode. :shock: A NGK BR7ES was the correct replacement.


Author: OldToroOwner

Date: 21 Dec 2006 11:00 am

Quote:
Ok, when I went to get some shear bolts the other day at Lowes I was looking at the snowthrowers, and I noticed that all of the Tecumseh 5.5 HP (smallest engine they had on a 2 stage) had RJ19LM spark plugs in them...

I've seen this before, also.
I still haven't figured out why some OPE have resistor plugs in them??
I mean, how much radio interference is a lawnmower going to cause??
Is it because of remote controlled garage door openers(or similar)??..
Anyone know??.... :?


Author: Vangellis
Subject: Re: spark plug

Date: 21 Dec 2006 7:02 pm

launboy wrote:
Yes, I know me again, with more questions... :shock: :?
Ok, when I went to get some shear bolts the other day at Lowes I was looking at the snowthrowers, and I noticed that all of the Tecumseh 5.5 HP (smallest engine they had on a 2 stage) had RJ19LM spark plugs in them...
When I got my Snapper with a 4HP tecumseh, the spark plug wa a cj8, so thats what I replaced it with. I know that running the wrong spark plug can cause something to get to hot or not hot enough... :? :? (just read it in a book to :x ) so, my question is, do I keep the CJ8 in it or switch to the J19LM.

I also noticed that my mower and most other OPE that i have with 4 cycle engines have the J19LM in them so thats what makes me think I should change.



Thanks,
Adam


Adam, don't be bashful. I think I asked the same question 3 winters ago. The cj8 and the rj19 are the same with the rj just being a resistor plug. AS OTO stated about interference with ? The TV on my handle bars?
Whatever. I'm here to learn and always ask questions and always get help from the knowledgable members. Thats why the forum is here. To share information and learn. I'm still a mechanical dummy, but a better one. :P

Kevin


Author: bez

Date: 27 Dec 2006 9:22 am

The cj8 and the rj19 are the same with the rj just being a resistor plug.


That is not true the 19 is a hotter heat range that the 8. with champion the higher the number the hotter the plug. I know NGK the lower the number the hotter the plug. The R is for resistor. The J is for a 14mm thread with a 3/8" reach that takes a 13/16" socket.
The resistor is needed on some units with electric ign module. I have seen some unit need module replaced because a non-resistor plug was used and caused failure. I know I thought it was crazy when I first hear it too.


Author: AJace

Date: 27 Dec 2006 5:19 pm

Thanks for the confirmation, Bez.


Author: launboy

Date: 28 Dec 2006 3:17 pm

Ok, so if it makes a difference, then I want to use the right plug.
So, does anyone know the right plug for my engine?
It's a Tecumseh 4 cycle 4 horse power engine, if that helps any... :?

Thanks,
Adam


Author: Marshall

Date: 28 Dec 2006 5:33 pm

I just got off the phone with Tecumseh direct. You're engine classification is an H4 (Horizontal 4 cycle). The 4 HP takes a CJ8.


Author: jubol

Date: 28 Dec 2006 5:42 pm

Marshall,

Nice going!!!!!!!!

Fred :lol:


Author: Vangellis

Date: 28 Dec 2006 6:50 pm

bez wrote:
The cj8 and the rj19 are the same with the rj just being a resistor plug.


That is not true the 19 is a hotter heat range that the 8. with champion the higher the number the hotter the plug. I know NGK the lower the number the hotter the plug. The R is for resistor. The J is for a 14mm thread with a 3/8" reach that takes a 13/16" socket.
The resistor is needed on some units with electric ign module. I have seen some unit need module replaced because a non-resistor plug was used and caused failure. I know I thought it was crazy when I first hear it too.


Shows you what I know. :roll:

Thanks Bez. My info came from a Deere dealership when I went to get some extras. They told me they didn't have any CJ8 plugs and the RJ19 were a suitable replacement. I do remember that someone had stated on here a long time ago about the resistor plug being "hotter".

Nice work Marshall.

Kevin


Author: buttlint

Date: 28 Dec 2006 8:07 pm

Posting engine numbers is more important than most people realize. Having model and spec number when you walk into a dealer for parts is a must. It saves them from the "You sold me the wrong parts" BS.
(From the Champion catalog.)
HSK840......CJ8Y/RCJ8Y
HH40..........J8C/RJ8C
HS40..........J17LM/RJ17LM
HSK40........J19LM/RJ19LM
HSSK40......J19LM/RJ19LM
H40............CJ8/RCJ8
TVS840.......J19LM/RJ19LM
LAV40.........J8C/RJ8C
LEV100.......J19LM/RJ19LM
OVRM40......N4C/RN4C
VH40, TVXL105, etc........
All Tecumseh 4hp engines.
The hp of the engine really means squat too a good parts person.


Author: ramit

Date: 28 Dec 2006 8:18 pm

Nice post, great info Linty!


Author: Marshall

Date: 28 Dec 2006 8:38 pm

Lint, good info.

Are the J8 and the J19 swappable? If not, what's the downside. I know many do swap them, what gets hurt?

When I spoke with Tecumseh I told them I had no model number but the engine was a 4HP L Head Snow engine on a Snapper. They said use the J8. That info either told them all they needed to know or they feel safe in saying use a J8 even if it's a J19, or some other.


Author: buttlint

Date: 28 Dec 2006 9:12 pm

Marshall.
Just a couple of quick personal observations.
I've never seen a problem with a J19lm substituted for a J8C.
In 30 years of motorcyles and small engines I have yet too see a hole in a piston from a wrong plug. (Not saying it never happened....just I have never seen it.)
Sticking a long reach plug in a short reach application will usually lock the piston. (On the first revolution of the crank.)
Sticking a short reach plug in something like an OHV long reach application does cause some problems with carbon building up the plug hole threads. The chunks of carbon get knocked back into the cylinder when the right plug is installed and that cant be a good thing..... but that is usually not fatal.


Author: Marshall

Date: 28 Dec 2006 9:34 pm

Well, if da man's never seen a problem interchanging those two, I feel certain there is none. :wink:


Author: launboy

Date: 28 Dec 2006 10:26 pm

Thanks everybody, you really are great!!!!

And very helpful and figuring all this stuff out!!! :)

I guess I'll keep the cj8 in there

Thanks,
Adam