Briggs Intek new head gasket

[Dale_W]

Model: 33R8 77 0008 G1
Serial: 14 0325 ZD 21021

This engine is mounted in an MTG lawn tractor. It started and ran good, but it was really blowing the smoke out the exhaust.

The head gasket between the cylinder and push-rod galley was leaking.

I replaced the head gasket with a new Briggs gasket and torqued the head bolts down to 220 inch pounds in a crisscross pattern.

On a cold engine, I rotated the flywheel until compression stroke TDC, ( used a 1/4" x 6 inch long extension in spark plug hole ), the continued to rotate flywheel until piston was 1/4" past TDC.

Exhaust valve was at .006
Intake was at .004

Now these were a wee bit snug, but close enough I figured. So I did no adjusting.

Engine started and idled fine. No smoke now. Yay.

Set to full speed, still good. Engage blade, still good. BUT when I put in drive the engine does not run smooth. It has a fairly consistent miss.

All I can think of is I did something wrong with the valve adjustment.

Are those specs and the procedure I followed correct?

Thank you.
Dale

[bluemower]

hard to say without seeing. One suggestion is to examine the sparkplug.

Since this had a blown head gasket, oil may have contaminated the sparkplug. The oil and carbon accumulation along the insulation may provide a path for voltage to flow. At high speed - no load, the spark will easily jump the sparkpulg gap and the engine runs smoothly. As the engine is loaded with blades engaged, wheels turning, and the weight of the operator, the pressures in the cylinder increase and more voltage is required to jump the gap. So the voltage finds an easier path down the carbon trail and you have a misfire.

[Dale_W]

Hi Bluemower
Thank you for the great explanation. The minute I pulled that plug I said 'Yikes, time for a new plug.'
But in my excitement (yes) to try out the repaired engine did I put in a new plug? I did not.

I just put in a new spark plug and that engine now runs great no-load and full-load.

Thank you for putting me back on track.

When looking for valve setting specs, I had a wide variety of answers from various sites on the web.
The best and seemingly most correct spec was
exhaust .005 - .007
intake .003 - .005

Do any of you guys have a quick reference to check those against this engine? Or can I say since it seems to run fine I can just call it done?

Thanks again for the help.

Dale

[38racing]

Those are the spec for 28 and 31 ohv. So expect correct for 33.

[bgsengine]

Hi Bluemower
Thank you for the great explanation. The minute I pulled that plug I said 'Yikes, time for a new plug.'
But in my excitement (yes) to try out the repaired engine did I put in a new plug? I did not.

I just put in a new spark plug and that engine now runs great no-load and full-load.

Thank you for putting me back on track.

When looking for valve setting specs, I had a wide variety of answers from various sites on the web.
The best and seemingly most correct spec was
exhaust .005 - .007
intake .003 - .005

Do any of you guys have a quick reference to check those against this engine? Or can I say since it seems to run fine I can just call it done?

Thanks again for the help.

Dale

Why not just swing by the downloads section of the forum and go pick up a copy of the Briggs Intek OHV single cylinder repair manual .. than all your questions to specs and torques might be answered?

[KE4AVB]

There is some several related info also there including an fairly up to date engine specs cheat sheet but it will need to be downloaded as some comments are not visible online using the Google viewer.

[bobodu]

Don't fix anything whut ain't broke...

[Dale_W]

bgsengine - "Give a man a fish, and you have fed him for a day. Teach a man to fish and ...." you know the rest.
Of course. The Downloads, Manuals and Links section.
I found the spec for 33 vertical.
intake .003 - .005
exhaust .003 - .005
Now I feel better about the clearances actually being out of spec when I put the head back on.

And Bob, nice to hear from you again. You are not wrong. I am going to measure again. They were mighty close.

Thanks again for the help.

[38racing]

Teach a man how to fish ... and he spends the rest of his life sitting in a boat drinking beer?

[bluemower]

appears to be a conflict between the engine manual and the briggs web site. the specification below is from the power portal. The manual was probably published years ago. Briggs may have changed the specification and issued a service bulletin.

SKU 33R877-0008-G1
Technical Specifications

Model Series 33R8
Displacement 540
Oil Capacity 48 oz (1.4 l)
Valve Configuration OHV
Flywheel Torque 110 lb/ft (149.0 Nm)
Governor Arm Torque 40 lb/in (4.5 Nm)
Carb Mount 70 lb/in (8.0 Nm)
Plug Gap 0.03 in (0.75 mm)
Intake Valve .003-.005 in