Briggs 17.5 PROPER valve Adjustment method Debate

Hello all,
Ok, watched 1000 videos and read a ton. Can you guys tell me best way to adjust the valves on a Briggs single cylinder OHV engine?

Debate is:
Method 1- These people say set to TDC and a little past (engines with compression release) and then adjust both valves to specs.

Method 2- These people say turn engine until 1 valve is completely compressed and the adjust the other valve to spec. Then turn engine and repeat procedure on the opposite valve. (as an aside, many people say set both to .004 and disregard Briggs specs).

So.... which camp are you in? I am trying to set these valves and do not want to burn a valve by setting them too tight! Please weigh in and let me know which method you use and why its better then the other. It seems that the manual recommends the TDC method. I AM CONFUSED.
Jeff

I set mine at spec using method 2 ,have NEVER had a problem doing it that way.

It’s taught and taught my students method #1. Haven’t ever had a problem. Method #1 is what you will find in every manufacturers service manual.

It matters not which one you use they both give the same result.
Method 1 is what Briggs recommend
Method 2 is what most auto mechanics are taught.
They are both right so stop obsessing over it.

The reason for method 2 is a lot of air cooled MOTORCYCLE engines have closing ramps ground into the cams.'
These are designed to make the valve shut slowly which drastically reduces the amount of noise that the valve train makes so it does not sound like your engine is about to blow up every time you run the engine;

Indian motorcycles use them and Harleys do not
If you ever hear them side by side the Indian engine is a lot quieter , note this is clatter from the engine, not exhaust .

Quietening ramps cost power and create more wear on the cam followers.
The ideal cam shape would be a sawtooth profile so the valve opens very quickly then slams shut under spring pressure with no resistance from the cam.
This is one reason why race engines are so mechanically noisy.

Depending upon the grind the gap between the valve stem & the rocker can make a big difference to the engine and is there to allow for thermal expansion.
The size of it controls when the valve opens , when it closes & how long it will stay open.
Just how critical it is depends totally on the grind ( shape ) of the pimple on the end of the cam.
With a tall and narrow pimple a difference of 0.0001" cam has a massive effect where as on a short & wide pimple ( most mowers ) 0.001" makes almost no difference.

Mower engines have what is called a "Soft" grind where the valves lift slowly, stay open for a long while & close slowly.
This robs the engine of potential power but it makes the engine a lot more robust.
Because of the soft grind there is a wide range of valve lashes over which the engine will run just fine.

Because the exhaust valve gets yellow hot during use while the inlet valve only gets to around 300 deg the exhaust valve needs a bigger space to allow for the extra thermal expansion.
Thus the valve lash for the exhaust valve is bigger than the lash for the inlet.

On a Briggs engine 0.004" is near the maximum for the inlet & minimum for the exhaust .
So to make it easier for those who have no idea about why they are setting the valve lash or are just plain lazy, a lot of techs will use 0.004" on both
Thus it rules out the chance that Mr brain dead sets the inlet to the max clearance for the exhaust and the exhaust to the min space for the inlet.

To get your head around how "softly tuned" a mower engine is look a the Hp of a single cylinder motorcycle engine of the same cubic capacity
A 500cc motorcycle engine will be 30Hp to 60Hp on the showroom floor standard
A 500cc mower engine will be 15Hp to 25Hp on the shop floor.

Neither. I use EIOC.

I set the intake valve at the point where the exhaust valve is just starting to open. (EO)

I set the exhaust valve at the point where the intake has just finished closing. (IC)

Method 1
Using the factory specs..


http://outdoorpowerinfo.com/engine_specs/briggs_valve_gaps.asp

Fish said:

Method 1
Using the factory specs..


http://outdoorpowerinfo.com/engine_specs/briggs_valve_gaps.asp

Click to expand...

Yes, that is easy, use the method specified by the people who designed and manufactured the engine as Fish and Rivets said. There is always some one who thinks they are wise on any subject.

Walt Conner

If you understand what you're doing, you don't have to follow any rote memory procedure.

http://wallaceracing.com/cambasics.htm

Question: What difference does the 1 or 2 make, when they both account for the cam not touching the tappit?

At 19:10, this shows what's going on.
https://www.youtube.com/watch?v=dWHPHGZAvj4

PTmowerMech said:

Question: What difference does the 1 or 2 make, when they both account for the cam not touching the tappit?

At 19:10, this shows what's going on.
https://www.youtube.com/watch?v=dWHPHGZAvj4

Click to expand...

The difference is if you adjust one valve while the other is fully compressed, the tappet is at roughly a right angle (90 degrees) to the cam lobe. You want the tappet you're adjusting to be directly opposite of the lobe, on the base circle. The sides of a cam lobe are not part of the base circle.