Briggs OHV Valve AdjustmentArticle by note Trotta

Through mechanical use and also wear, tiny gas engines require valve adjustment native time come time.If your engine is not starting or to run poorly, it might be the valves are not completely opening and also closing.

You are watching: How to adjust valves on briggs and stratton 12.5 hp


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To store your engine running it"s best, valve clearance need to be checked and readjusted as part of periodic maintenance.The procedure for adjusting valves on Briggs OHV motors is usually the very same for every models.

NOTE: Lawn mowers, lawn tractors, and also pressure washers all run at a short RPM level.Unless your engine is powering a race kart, over there is no require to adjust valves if they"re only out the spec through .001" or .002".

This article describes how to readjust valves on two various Briggs & Stratton motors.The an initial is a Craftsman press washer through a 7-hp motor, the 2nd is a man Deere lawn tractor with a 19.5 hp motor.

Why Valve Clearance Is Important

If a valve has too much clearance, that doesn"t totally open.This robs the engine of power.


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If a valve doesn"t have enough clearance, that doesn"t completely close. This allows some compression come escape with one or both valves.Aside from losing power, the affected valve(s) may come to be overheated.

Valve Clearance Specs

Valve lash, or the room between the valve and also rocker arm, different slightly native engine come engine, so check the specs top top yours.Valve clearance specs deserve to be uncovered in an owners hand-operated or shop manual. Friend can additionally find the specs online, however will need to know the engine design number.

NOTE: constantly check and change valves once engine is cold.

Set Up your Workspace

Rather 보다 kneel and bend down while working, I prefer to bring the work up to a an ext comfortable height.The much less contorting you have to do, the much easier the service will go.


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Briggs-powered Craftsman press washer (7 horsepower)

Tools Needed


3/8" socket (1/4" journey ratchet preferred)Spark plug socket (3/8" journey ratchet preferred)Feeler Gauge3/16" Allen key5/8" Open finish wrenchLong screwdriver (optional)
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NOTE: You execute not have to drain the engine oil before taking the valve sheathe off.

Remove Valve Cover

Here"s another advantage to propping up the work-related to a better working angle.The valve cover comes turn off with four 3/8" headed bolts.The very first time i took a Briggs OHV valve sheathe off, I only saw the 2 side bolts, and after removed those two, behavior to try prying off the still-bolted-on cover!


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Looking within the valve cover provides you a great indication as to whether the engine oil was changed regularly.On this motor, i was pleased come see just how clean the rocker arms, valve springs and also valves were.

Remove Spark Plug

Removing the spark plug reduce engine compression, making that much less complicated to traction the begin rope to move the piston and valves into position.With the valve covering off and also the spark plug removed, you can pull the begin rope and also watch the valves open and also close.

How To examine Valve Clearance

There are two well-known methods for checking valve clearances.The encourage procedure native most service manuals is technique #1, wherein a screwdriver is supplied to gauge the piston"s range of motion.

Method #1

Insert a narrow screwdriver into the spark plug hole and also touch the piston. Traction the start rope and also move the piston/valves. The driver goes up and down accordingly. Once the driver sticks the end the most, the piston is at the top of it"s travel. This is recognized as optimal dead center, or TDC.

Move previous TDC until the piston has actually moved under 1/4".You will now have actually slack ~ above both entry (upper) and also exhaust (lower) rocker arms.


Check the valve clearances one at a time by put a feeler gauge between the every valve and also rocker arm.Adjust as essential (see "How To adjust Valve Clearance" below).

Method #2

For this method, friend don"t need to discover piston TDC, yet it will take an additional step.You will start with the intake side first, adhered to by the exhaust side.

NOTE: Some electric motors will have the intake rocker arm on the top.Some electric motors will have actually the exhaust rocker eight on the top.You deserve to usually follow the path of the input manifold (or the muffler pipe) to determine which is which.

Intake top top Top, Exhaust ~ above Bottom

Pull the start rope slowly.When the bottom rocker pushes the exhaust valve in, the height (intake) valve will have slack.You deserve to now examine the entry valve clearance and adjust if needed.


After the intake side is done, traction the start rope slowly, and watch for the optimal rocker to push the entry valve in.The exhaust valve will now have actually slack.Check clearance and change if needed.

How To adjust Valve Clearance

Loosen the lock nut on height of the rocker arm by turning it counterclockwise. Make a mental note as to how tight it was.This will help when re-tightening.


Set your feeler gauge to the recommended setting for your engine.Remember the intake and exhaust settings might be different.

Insert the feeler gauge in between the rocker arm and the valve and check the clearance.

If the void is too wide, take it an Allen key to rotate the center adjusting screw clockwise in the rocker arm.You will only have to turn it a very tiny amount.When the gap is correct, the feeler gauge have to fit snug, yet still may be to move in and out there is no binding.

Once the mediate is completed, hold the Allen an essential in place and tighten the rocker nut v an open-end wrench.

Remember as soon as you loosened the lock nut, how tight it was?The suitable torque value is about 45 inch-pounds.Hold the rocker nut v a wrench and also tighten the rocker round set-screw. Be cautious not to over-tighten it.


Using the same procedures, examine and adjust the exhaust valve.

NOTE: On part Briggs engines, the nut and set-screw room positioned over the press rod ends.

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The valve clearance specs on my Craftsman push washer were:

Intake Valve .004" to .006"

Exhaust Valve .004" come .008"

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When done, double-check the settings before re-installing the rocker cover and spark plug.

Rocker cover Gasket

Inspect the old rocker covering gasket.If it"s not ripped or torn, re-use it.If it"s damaged in any way, you have the right to either change it with a new one (easier) or usage RTV gasket machine (messier).Be careful not come over-tighten the bolts (a common mistake).


Shop:Briggs & Stratton 691890 Rocker cover Gasket


After the engine is ago together, begin it up and let it operation for 10 minutes or so.This will certainly burn off any residual grease and oil. Then inspect the rocker covering bolts and re-tighten as needed.

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Adjust Valves ~ above Briggs Intek OHV

Adjusting valves on my Briggs-powered lawn tractor was comparable to the push washer.A minor distinction was that the optimal valve was exhaust, not intake like the 7-hp motor.


Remove the bolts holding on the rocker cover.Remember that valve clearances are checked and readjusted while the engine is cold.


Since there"s no start rope to pull on this lawn tractor, here"s one alternate way to relocate the valves.With the spark plug removed, grab the height of the flywheel screen and you deserve to turn the motor over by hand.


Exhaust on Top, entry On Bottom

When the bottom rocker pushes the intake valve in, the height (exhaust) valve will have slack.You have the right to now check exhaust valve clearance through a feeler gauge.

If not within spec, loosen/adjust rocker nut to achieve the preferred clearance, climate re-tighten.Hold rocker nut and tighten the rocker ball set-screw come the ideal torque value (about 45 inch-pounds).

After the exhaust side is done, revolve the engine slowly, and watch because that the top rocker to press the exhaust valve in.The input valve will certainly now have slack.Using a feeler gauge, examine valve lash.

If no within spec, loosen/adjust rocker nut to achieve the wanted clearance.Hold rocker nut and tighten the rocker sphere set-screw come the ideal torque worth (about 45 inch-pounds).

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The valve clearance specs top top my man Deere LA110 lawn tractor were:

Intake Valve .003" come .005"

Exhaust Valve .005" come .007"

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After ns was done with the valve adjustment, i double-checked my settings, then re-installed the rocker cover with a new gasket (Briggs # 272475s).


Shop:Briggs & Stratton Rocker covering Gasket

I likewise installed a brand-new spark plug (Champion RC12YC) through .030 gap.