Small engine spark plug chart

[captain14]

I tried to search on GJ and the internet but it eludes me.

I am looking for a small engine compatibility chart to match my mower to the correct spark plug. I went to HD and they didn’t have the book by the plugs they used to. Previous attempt at AAP was useless. Said they couldn’t help me.


Small engine is a B&S Quantum 6.5 HP on a Craftsman lawnmower.

Last year the mower was running like garbage, pulled the plug and it was covered in black crud.
I hit it with the wire brush and it ran great. The last time or two I was mulching leaves it was starting to show the same tendencies.

I plan a getting a couple of new ones this week when I can find a match.

Thanks in advance.

 

[duneslider]

Is there not a number on the plug? I think my local walmart still has lawnmower plugs and the book.

 

[Bucko]

If your plug is the correct one there are a bunch of websites with cross-reference. Here is one...

sparkplug-crossreference.com

www.sparkplug-crossreference.com

The other option is to get the model number for the mower from the data plate. Put that into Google search with the "manual". Usually they are online somewhere and you can print it off. The correct plug will be listed.

 

[Leaflessshadetree]

There are plenty of sites search by engine model and /or serial number.
I also have downloaded complete part manuals from the Briggs and Stratton site.

 

[captain14]

Bucko said-
“The other option is to get the model number for the mower from the data plate. Put that into Google search with the "manual". Usually they are online somewhere and you can print it off. The correct plug will be listed.”

Thanks for the help.

I found the plug number on the owners manual online. I entered the model number and found what I was looking for.

I have two plugs for pickup at the local AAP tomorrow.

 

[nadogail]

A spare spark plug should be as common as a spare tire.

 

[Mick56]

Air filters can be pretty touchy on the engines too, even if they don't look bad. I would replace that at the same time.

 

[Ilchik]

From what I've found, the OEM plug is Champion QC12YC (946). Here are cross-reference spark plugs for it:

Champion QC12YC (946) Spark Plug Cross Reference

See the cross-reference plugs for Champion QC12YC (946) and similar plugs with 14 mm x 1.25 mm thread, 19 mm (3/4") reach and 0.75 mm (.030") gap.

vinsonar.com

 

[four.cycle]

Small engine is a B&S Quantum 6.5 HP on a Craftsman lawnmower.

The Quantum engine on a walk-behind lawnmower is a flathead engine and does not use a long-reach plug.

I run Autolite/Motorcraft #255 in all Briggs & Stratton and Tecumseh flathead mower engines. ($2.49 at O'Reilly's)

Factory plug was probably a CJ8Y Champion.

The ONLY time I will run a Champion plug is if I get stuck building one of those ****** "Intek" engines, in which case you run a Champion ONLY and bring the gap down to .017" (because of an inherent engineering issue with the coil pack.)

If it goes in the hole, it's a spark plug.

Generally speaking this is true. ANY 14mm thread x 3/8" reach plug will make that lawnmower run. AC #44 or #45 or #44S or #45S or Autolite A42 or A52 - they'll all run. Some models you have to use the tiny "peanut" plug because the lead from the ignition module (coil) won't reach the longer (conventional) plug. Otherwise, anything that screws into the hole that doesn't hit the piston will make the engine run. It's a lawnmower - not a Lamborghini.

QUANTUM engine in walk-behind lawnmower:



INTEK engine in walk-behind lawnmower:

 

[BillK]

Go to Jacks Small Engines and use either your mower model number or the engine model and serial number.

https://www.jackssmallengines.com/

Either that or find a "real" mower shop near you and give them a little business.

 

[four.cycle]

^ or partstree.com

you need the MODEL, TYPE, and CODE numbers for a Briggs and Stratton:
on that Quantum they're stamped just above the spark plug on the blower housing - see photo above.

 

[Motown]

The correct plug is Champion RJ19LM

 

[laser3kw]

The B&S Quantum engine uses different spark plug type depending on the date code. Check the date code and then find the recommended plug for that engine.

 

[nbpt100]

The B&S Quantum engine uses different spark plug type depending on the date code. Check the date code and then find the recommended plug for that engine.

Yes but the Rj19lm or j19lm will work just fine and are available at most all autoparts stores for under $3. Some of the later models came with a RJ19LMC. It has a solid copper grounding strap vs. copper plated.. When ever I tried to buy one at the autoparts store they never had one and said if they did it would cost something like $13. While other later models came with the eco clean plug in the link below. I assume it burns cleaner or has some eco benefit. The gap on most of the auto choke (Ready Start) carbs is .020. The others are .030.
I usually ask for the J19LM and they work just fine. Otherwise, I will take the RJ19LM if that is all they have. In some instances I get the NGK if all other stuff is out. I think it is a BR-2 Don't quote me but what ever it x-refs to it works just fine in the Briggs engines.
In my experience Champions run great in Briggs and Tecumseh Engines. Not so well in Asian. That is my experience.

Champion Eco-Clean 13/16 in. J19LM Spark Plug for 4-Cycle Engines 861ECO

Champion spark plugs have a fine-wire center electrode that creates a sharp-focused spark for faster, more consistent starting. The patented rib core nose fights fouling and provides an alternate spark

www.homedepot.com

 

[Junkdrawer Dog]

A spare spark plug should be as common as a spare tire.

Well said! I grew up on 60s and 70s vintage two stroke motorcycles. You wouldn't ride down to the mailbox without a spare plug and plug wrench!

 

[Showkey]

Between plug improvements and “electronic“ ignition system the need for plug swap and plug fouling is far less of a problem. I have two mowers that are 30 plus years old with the original plug. Same with a chain saw, tiller and snow blower ….they see less use……but are over 20 years old.

Prior thread on Vehicle plug maintenance……..many have plug swap at 105k miles. Even at that point there’s no issues. Modern vehicles have a very sensitive misfire detection so theres an immediate indicator there is a problem. But, misfire still might not be a plug issue.

 

[nbpt100]

Between plug improvements and “electronic“ ignition system the need for plug swap and plug fouling is far less of a problem. I have two mowers that are 30 plus years old with the original plug. Same with a chain saw, tiller and snow blower ….they see less use……but are over 20 years old.

Prior thread on Vehicle plug maintenance……..many have plug swap at 105k miles. Even at that point there’s no issues. Modern vehicles have a very sensitive misfire detection so theres an immediate indicator there is a problem. But, misfire still might not be a plug issue.

Your experience is close to mine. On my stuff I will check the gap and put it back in. They last so much longer than the general public has been led to believe. In most late model small engines the Maintenance interval is about 100 hrs of run time. On a healthy engine they can usually go much longer as your example shows. It use to be be 30 to 50 hours. Pulling the plug and looking at it can give clues as to how the engine is running and can help trouble shoot other problems.
Plugs are pretty cheap and a lot of shops will just change them out almost reflexively. The labor is the same and the part cost is low. I have been guilty of that myself in some cases.
I just do not want to deal with a potential issue on a snow blower in 10 degrees. etc. On lawn mowers I just keep them going until they look bad or have running issues.

 

[gahrajmahal]

All I could find. Interesting for me is I often find loads of engineering charts and helpful summaries on Pinterest. I looked there for small engine spark plug charts and none came up, but I won’t be surprised if something shows up later on.

 

[cpttuna]

Check Wal-Mart at the end of mowing season. most of their lawn and garden parts are put on clearance. i got plugs last year for $.99 each.

 

[Two Speed]

On a whim I checked on rockauto since I was getting some car parts anyway, and scoreed an NGK for 99c.

 

[nbpt100]

On a whim I checked on rockauto since I was getting some car parts anyway, and scoreed an NGK for 99c.

I hope the shipping wasn't $8. Just kidding........ sorta. Good find.

 

[DenisG]

Here's one from Stens:

https://www.stens.com/web-assets/media/quickref/Chart%20-%20Spark%20Plug%20Application%20-%20Gas%20Engines.pdf?_ga=2.124823242.1527863810.1659788366-392228585.1659788366

Other quick reference guides from Stens:

Quick Reference Guides

www.stens.com

 

[Two Speed]

I hope the shipping wasn't $8. Just kidding........ sorta. Good find.

I was ordering other parts, so it didn't add anything to the shipping. I'll do that with filters, or other small items that are at a good price and keep adding one until the shipping gets bumped up and then toss one from the cart.