Adjusting valves on a 17 hp briggs & stratton motor

"gump 01, here is a general idea about some of the B&S engines. O could probably provide you with a bit more in depth information, if I would know which engine model you have. :"" Adjust Valve Clearance

All Models - Except Vertical Models 110000, 120000 Early Production

NOTE: Check valve clearance while the engine is cold.

1. Turn crankshaft counterclockwise until piston is at top dead center on the compression stroke. This prevents the compression release from holding the valves open.

2. Insert a narrow screwdriver or rod into the spark plug hole as a gauge, then slowly turn crankshaft counterclockwise until the piston has moved down the bore by 1/4” (6mm).

3. Using a feeler gauge (A, Figure 41), adjust rocker nut to obtain the clearance as listed on the bottom o this answer.

4. Hold rocker nut and tighten the rocker ball setscrew (B) to the torque valve of 45 lb-in. (5 Nm).

5. Check clearance again and re-adjust, if necessary.

6. Repeat for other valve.

NOTE: On some models, the nut and setscrew are positioned above the push rod ends.

Vertical Models 110000, 120000 Early Production

1. Using a feeler gauge (A, Figure 42) adjust the locking hex nut (B) to obtain the

correct clearance as listed on the bottom of this answer.

2. Repeat for other valve.

- OR -

1. Loosen jam nut (A, Figure 43) at base of rocker arm stud. Then, using a feeler gauge (B), turn rocker arm screw © to obtain the correct clearance as listed on the bottom of this answer.

2. Hold the screw and tighten the jam nut to value 45 lb-in. (5 Nm).

3. Check clearance again and re-adjust, if necessary.

MODEL 110000 HORIZONTAL SERIES

Valve Clearance – Intake .004 - .006 in. (.10 - .15 mm)

Valve Clearance – Exhaust .009 - .011 in. (.23 - .28 mm)

MODEL 120000 HORIZONTAL SERIES

Valve Clearance – Intake .004 - .006 in. (.10 - .15 mm)

Valve Clearance – Exhaust .009 - .011 in. (.23 - .28 mm)

MODEL 150000 HORIZONTAL SERIES

Valve Clearance – Intake .004 - .006 in. (.10 - .15 mm)

Valve Clearance – Exhaust .009 - .011 in. (.23 - .28 mm)"

"Additional info:

I have a 17.5 HP Model 31C707.

Valve Clearance – Intake .003 - .005 in.

Valve Clearance – Exhaust .005 - .007 in.

I prefer to not stick anything metallic down the spark plug hole. A disposable chopstick works fine and makes it easy to mark at TDC, then put a second mark 1/4 inch farther out."

This information is wrong!! Top valve on this engine is EXHAUST! Bottom is intake

"I used a pencil for marking TDC and it must have been brittle because a portion broke off in the spark plug hole.

I manually rotated the cylinder but can not see it.

Will I have to disassemble the engine to get this out?"

"Just like Mike I have a 17.5 HP Model 31C707 on a craftsman lawn tractor. But this information did NOT work for me, though it is the same as Briggs and Stratton -- https://www.briggsandstratton.com/na/en_...

Well first of all, I had a bent intake push rod. The stud came loose and messed everything up. It even broke a rocker arm. So after spending a good hour trying to put the new push rod in the valve and getting them to stay (I finally took the valve guide off and stuck the rods in it, finally got them to stay and then carefully put the screws in) I followed this guide exactly. I set the clearances as Mike said.

When I went to start it, the engine would barely turn over. So I asked the guy who sold me the parts how to do it. He said to turn the flywheel clockwise, the way it spins, until one push rod is extended out as far as it will go. THEN you set the clearance on the other rocker Arm. Do the same for the first rocker arm-- keep turning the engine until the other push rod is all the way out, and set the clearance. My engine started right up and runs better than it did when it was new.

So I don't know what is going on, but I tried setting the valves as this guide here says and I tried setting them when the piston was at top dead center without going down 1/4 inch. (I got that from a youtube video.) And I tried the way that worked. And the clearances were WAY different in each case! It's not like you can use one method the same as the other.

Oh, one other thing the mechanic told me to do- put some blue loctite on the the studs. They take a ten mm wrench. ALSO, you need a t20 torx bit to loosen and tighten the set screws."

No need to find top dead center (TDC)! Just adjust with both valves CLOSED.