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Adjust valves to specs. with engine cold.
post model, type, trim, & code #'s from your engine into website above for your engine parts & specs.

Please post the units serial number. With it I will be able to identify which engine you have. With what you posted so far, I doubt it you have a coil or valve problem.

"The mower seems like it might have a mild, almost unnoticeable miss sometimes while not under load,"
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A vacuum leak can cause that . There is more vacuum at low speed . Check hoses , carb mounting etc .

The mower is a 20334 with a Briggs 7hp, SN 10 0428 56 29693, build date 04/10. So far I've pulled the carb and cleaned it, replaced the plug and air cleaner, removed the muffler to be sure there was no clogged screen, pulled the top of the motor and cleaned the flywheel magnets and coil, made sure that the choke was working properly, then adjusted the gap to .010, sprayed seafoam in the carb while running, put Seafoam in the tank, and replaced the battery.

When cold, the mower will crank and crank and crank trying to start but won't... as if it's turning over too slow but it's not per the YouTube videos I've watched. If I pull the rope, it fires right up, unfortunately the owner is elderly and can't pull as hard as me. Once the motor has run, it usually starts on the electric starter. When I watch YouTube videos, these things light right off. The only thing that I haven't and most likely won't do, is get into the valve adjustment not being an OHV motor.

Please post the mowers serial number as I don’t remember Toro installing a 7hp Briggs engine on their steel deck mowers.

10 0428 56 29693

Those are Briggs numbers. I need the Toro numbers, look under rearbagger cover.

First, this is a 2010 model. When you cleaned the carb, did you replace the float needle and seat, plus adjust the float level? I’m guess that being that old the seat has swelled and it is resulting in a lean starting and running condition. I normally set the float level slightly rich which results in easier starting.

Rivets said:

First, this is a 2010 model. When you cleaned the carb, did you replace the float needle and seat, plus adjust the float level? I’m guess that being that old the seat has swelled and it is resulting in a lean starting and running condition. I normally set the float level slightly rich which results in easier starting.

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I did not, I pulled it apart and cleaned it, that was it. I was surprised at how clean everything was. I should have at least checked the float level.

See pages 9 & 10 in manual above, engine specs. your engine intake & exhaust valves should be adjusted to .004-.008 with engine cold.

Lyndmc said:

The only thing that I haven't and most likely won't do, is get into the valve adjustment not being an OHV motor.

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Unfortunately, that's probably exactly what it needs now.

Personally I doubt your problem is valve clearance. To many times valves are blamed before easier solutions are exhausted.

Rivets said:

Personally I doubt your problem is valve clearance. To many times valves are blamed before easier solutions are exhausted.

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Sounds like he's run through the easier options.

It’s a whole lot easier to check the float level in the carb than adjusting the valve clearance on a L-Head engine.

It’s not too difficult to check the valve clearance. Just remove the muffler to access the valve cover. Make sure the engine is a top dead center on the compression stroke.

Adjusting the clearance is more involved. You’ll need to remove the head and valves. The valve tip has to be ground or filed to increase clearance.

If my memory is any good, the cover to access the valve stems, is behind the carb.

Rivets said:

If my memory is any good, the cover to access the valve stems, is behind the carb.

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There’s a good chance you’re right. I haven’t worked on these late flatheads before. I looked up the 2010 Toro 20334 and found it should have a B&S126T05-0933-B1engine. The engine parts diagram shows the same basic configuration they’ve used for decades, which shows the valve access cover next to the exhaust port.