Here is something else I do to gasoline engines, index the plugs. You get a plug insert and drill a hole in a plate to mount the insert. Then mark the plate off in 10 degree increments. You wrap a plug with a piece of tape and mark the side that is facing the piston in this case a Kohler K17 engine. Screw the plug into the plate and see where the mark is aligned degree wise.

You can see that that the spark can be blocked if the open end is facing the wrong way. On car engines this can have a big impact on gas mileage.

Something else I do to the Kohler engine is add a MSD-5 capacitor discharge ignition. This allows the ignition points to last forever.

The Honda Insight is a model that utilizes indexed spark plugs from the factory. These plugs are designed with a specific orientation of the gap to optimize combustion efficiency and fuel economy.

The Honda Insight has indexed spark plugs from factory, with four different part numbers available corresponding to the different degrees of indexing to achieve most efficient combustion and maximum fuel efficiency.

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Originally posted by 41:

The deck measured .220 inches thick. The lawn tractor weighs about 1400 pounds with a 200 pound person.

A 5 gauge deck, almost 1/4" thick. That'd take quite a press to mould those decks.

New John Deere X730 up to the X758 model machines are running 9 gauge steel for the deck shells for their new Hi-Capacity decks. (0.1495")
The John Deere X720 with the commercial 7-Iron deck that I recently traded in was 7 gauge for the deck shell. (0.1793")
It took three men and a boy to tip it up on edge for doing tasks underneath the deck.

quote:

Originally posted by 41:
Here is something else I do to gasoline engines, index the plugs...

Thanks, 41, I had no idea this was a thing. So if out of index, compromised performance, a little or a lot? Is it a big deal in a world of maximized efficiency but only so much otherwise?

In your typical single cylinder flat head 1980's vintage air cooled lawnmower engine, the performance increase is going to be so small, it cannot be measured.
The higher the power density (HP output vs displacement), indexing spark plugs results increase. But still likely less than 3% even in a best case situation.
In almost all cases, the "juice" simply isn't worth the "squeeze" and is needlessly complex.

Here is an AI generated answer about indexing spark plugs.

Spark Plug Indexing Performance Gain.

Indexing spark plugs can typically result in a performance gain of less than 1% of the total engine output. For a 500 horsepower engine, this translates to only about 5 horsepower.
Some users have reported slightly higher gains, such as up to 3% more power on a turbocharged 4-valve 2.3L engine, but these are exceptions rather than the norm.
In most cases, the gains are minimal and often difficult to measure without specialized equipment like a dyno.

NGK Spark Plugs: Reports that indexing can make only a few more horsepower, usually less than 1% of total engine output.
Speed-Talk Forum: Mentions a 3% power gain in a specific turbocharged engine scenario, but generally agrees that gains are minimal and often less than 1%.
These sources indicate that while indexing can potentially improve performance, the gains are typically small and may not be noticeable in most applications.

My 1990 C2500 went from 17 to 21-22 MPG. I change plugs every 25 to 30 thousand since the insulator breaks down and the plug arches over down inside the plug.

I changed plugs one time and the mileage didn't improve. So I thought a plug was bad but further investigation showed that two plugs had the ground electrode blocking the spark.

My water pump will run 1 1/2 hours on a full tank of gas but with the plug indexed will run 1 3/4 hour with the same output pressure or load.

I was unaware of the Honda Insight doing that from the Factory. That's the EPA squeezing auto/truck makers for every 1/10 of an MPG.

I see another problem with the steel plate and spark plug thread insert spark plug clocking tool.

For every other spark ignition engine made here on earth, there is no guarantee the lead in thread in the actual cylinder head starts at the same degree position as the degree plate/threaded insert.
The spark plug threaded holes in the cylinder heads are done with automated machinery.
They don't give a rats ass where the tap or thread milling cutter start point is rotationally.

So in my humble former ASE Master Certified Auto Technician and tool & die/model shop machinist background, totally unnecessary and grossly over complex, for a sub 1% gain at best.

We use to race cars and index plugs with washers.


SPi Spark Plug Indexing Washer Kit for Twin Cylinder Machines

Indexed spark plugs provide better fuel mileage and increased spark plug life
Align electrode with intake port
Hottest part of spark flame meets fuel charge head-on
Mark electrode side of plug and index with various washers to achieve correct aim
Includes 8 anodized aluminum washers for 2-cylinder applications

https://www.partsgiant.com/p41...1282205d0c3322f3f2c5

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For every other spark ignition engine made here on earth, there is no guarantee the lead in thread in the actual cylinder head starts at the same degree position as the degree plate/threaded insert.

That is the whole concept of measuring where the thread starts for each cylinder. I go to Advance Auto with my index plate and a list of plug indexes and select the plugs that match my list.

So you open up many packaged spark plugs and try them in your index plate. What about the spark plugs in sealed cellophane wrappers. Do you open them up?
Please let me know where your Advance Auto store is located that allows you to paw through their stock of spark plugs.
I don't purchase spark plugs very often, but I do want to be certain I don't purchase spark plugs where you are buying them.

If you are using small engine spark plugs with compressible gaskets used for sealing, how do you account for gasket crush and the effect on degrees of rotation while the gasket crushes?
Do you torque crush style sealing washer spark plugs into your index plate with a torque wrench prior to buying them? If so, then they are "used" spark plugs, being resold as "new" spark plugs.
What about variations in spark plug gasket crushability?
Never mind, don't tell me.

It's a good thing I am not the Manager at your Advance Auto store.
I personally would tell you not to return with your index plate.

The Advanced Auto Manager lets me select the plugs. He was curious about the index plate and how it works. He made up a plate for his two cars and was all smiles the next time I went in there.

quote:

Originally posted by 41:
The Advanced Auto Manager lets me select the plugs. He was curious about the index plate and how it works. He made up a plate for his two cars and was all smiles the next time I went in there.

If I was racing cars, I might go to the trouble. Cutting grass with a lawn tractor, not so much.