B&S L-Head Spark Plug Question
- Thread starter TriMoto
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That decade of the 90's, late in the decade.
Heat range and because they can.
+1 to jhellwig.
My hunch has to do RE: B&S trying to raise the compression ratio on their flathead engines, also attempt with their last ditching effort to compete/comply with EPA emissions standards imposed since the 90s (well into the 2k and beyond, as you noticed on all mower engine blocks there's an emissions rating bar).
Changing the spark plug to RJ19LM or so is to alter the heat range to compensate the raised engine compression ratio.
Q.
My hunch has to do RE: B&S trying to raise the compression ratio on their flathead engines, also attempt with their last ditching effort to compete/comply with EPA emissions standards imposed since the 90s (well into the 2k and beyond, as you noticed on all mower engine blocks there's an emissions rating bar).
Changing the spark plug to RJ19LM or so is to alter the heat range to compensate the raised engine compression ratio.
Q.
My Craftsman push mower uses a different spark plug than my edger and reel mower even though they're all L-heads. I just shrug it off and go buy what's specified.
Originally Posted By: Merkava_4
My Craftsman push mower uses a different spark plug than my edger and reel mower even though they're all L-heads. I just shrug it off and go buy what's specified.
does it spec a rj19hx? My Craftsman mower specs that, but they are a little hard to find. Seems to be a fine wire racing plug. I think they were used in some of the Easy Start engines
My Craftsman push mower uses a different spark plug than my edger and reel mower even though they're all L-heads. I just shrug it off and go buy what's specified.
does it spec a rj19hx? My Craftsman mower specs that, but they are a little hard to find. Seems to be a fine wire racing plug. I think they were used in some of the Easy Start engines
My Craftsman push mower uses a BR2-LM and my edger and reel mower both use BM6A. Those are NGK numbers.
NGK BR2LM equates to Champion RJ19LM.
http://www.sparkplug-crossreference.com/convert/CHAMP_PN/RJ19LM
of all the Champion RJ19LM varieties I have on hand: only the EZ start version has fine tip.
Q.
http://www.sparkplug-crossreference.com/convert/CHAMP_PN/RJ19LM
of all the Champion RJ19LM varieties I have on hand: only the EZ start version has fine tip.
Q.
J19LM in engine's that originally spec'd a J8/CJ8.
Are these plugs interchangeable. Uf so what advantage does either have over the other. My Husqvarna is likely an early 90's I bought used and says to use the CJ8. It is a 12 HP Briggs and is on one of their articulating mowers.
Thanks
Are these plugs interchangeable. Uf so what advantage does either have over the other. My Husqvarna is likely an early 90's I bought used and says to use the CJ8. It is a 12 HP Briggs and is on one of their articulating mowers.
Thanks
Originally Posted By: Quest
Changing the spark plug to RJ19LM or so is to alter the heat range to compensate the raised engine compression ratio.
OK, so what would happen if I installed a CJ8 into an engine that specifies the RJ19LM plug?
Changing the spark plug to RJ19LM or so is to alter the heat range to compensate the raised engine compression ratio.
OK, so what would happen if I installed a CJ8 into an engine that specifies the RJ19LM plug?
This all came about when Federal Mogul bought Champion/Cooper out in the 90s.They had a rash of complaints about the plugs failing at an early age.Champion blamed the fuel at the time claiming it wasn't 1960s fuel anymore.They had to re-do the heat ranges on many plugs and the recommendation no longer matched many OEM numbers.Its a time that they have been trying to live down for the past 20 years.Many people went Autolite due to the whole fiasco and never went back.
Originally Posted By: Merkava_4
Originally Posted By: Quest
Changing the spark plug to RJ19LM or so is to alter the heat range to compensate the raised engine compression ratio.
OK, so what would happen if I installed a CJ8 into an engine that specifies the RJ19LM plug?
You'd never know the difference... After 5-10 hours you could read plug and adj heat range if necessary...
As far as higher compression, generally colder plugs are used to prevent preignition... Probably the hotter plug is a emissions requirement, not something that actually beneficial for engine... Before computers & fuel inj, was also a practice of the auto mfgr's to use overly hot plugs(remember all those dieseling engines of the '70s? that wouldn't shut down on a hot day?)...
Originally Posted By: Quest
Changing the spark plug to RJ19LM or so is to alter the heat range to compensate the raised engine compression ratio.
OK, so what would happen if I installed a CJ8 into an engine that specifies the RJ19LM plug?
You'd never know the difference... After 5-10 hours you could read plug and adj heat range if necessary...
As far as higher compression, generally colder plugs are used to prevent preignition... Probably the hotter plug is a emissions requirement, not something that actually beneficial for engine... Before computers & fuel inj, was also a practice of the auto mfgr's to use overly hot plugs(remember all those dieseling engines of the '70s? that wouldn't shut down on a hot day?)...
dunno of the champion/FedMogul fiasco but regardless, there are 2 ways to find out if the plug works (rather crudely):
(*aside from doing all the usual measurements RE: thread lengths, tip exposure height, etc.*)
(a) find a fine wire and poke it all the way into the bottom of the gap where the ceramic center electrode meets the metal body part. Compare that length (distance) with the RJ19LM you have. If the depth is right, then the heat range should be close.
(b) run the spark plug for 8~20 hours and read the tip (ceramic electrode). Also: observe to see if there's any misfiring (too "hot" of the tip) or heavy carboning of the tip (too "cold").
Q.
(*aside from doing all the usual measurements RE: thread lengths, tip exposure height, etc.*)
(a) find a fine wire and poke it all the way into the bottom of the gap where the ceramic center electrode meets the metal body part. Compare that length (distance) with the RJ19LM you have. If the depth is right, then the heat range should be close.
(b) run the spark plug for 8~20 hours and read the tip (ceramic electrode). Also: observe to see if there's any misfiring (too "hot" of the tip) or heavy carboning of the tip (too "cold").
Q.
Merava_4, try it. I use what's in stock, they run like a Briggs.
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