ACR

[hardscrabble]

I have a 44" Swisher trailer mower with an 11 hp Briggs engine. Up until last summer it"s been a good starter. Now, if I try to pull the rope, it almost tears my hand off. This engine is supposedly equipped with Automatic Compression Release, and I"m guessing that"s what malfunctioning. What do I open up to find this? And then what can I do to fix the problem? Thanks in advance for any suggestions.

Perry Moe

 

[joe csuti]

Before tearing eng apart,if eng an ohv,check valve clearances,after that if eng an L head or ohv,check that float valve in carb not leaking & flooding eng when at rest,filling cyl with gas & hydro locking piston on compression stroke,if valves/carb ok then side cover or crankcase will have to removed,depending if eng horiz or vert shaft to get access to cam,as acr mounted on/part of cam assembly

 

[Kentb of SWMO]

WHAT is the Model, Type and Code Numbers from the engine? There were many 11 HP Briggs engines built that DID NOT have an ACR. Is this a "L" head or an OHV engine? More info is needed.

Kent

 

[hardscrabble]

Model 21A302
Type 0166E1
Code 041222ZA
OHV
vertical shaft

 

[hardscrabble]

And also, I've had the spark plug out and turned it over. No gas or anything. Just air.

 

[joe csuti]

Check valve clearances,should be .004"-.006" on both intake & exh,try setting both at .004" and see if that works.

 

[Kentb of SWMO]

Since this is a Briggs OHV engine, the ACR is done by the intake valve. Turn the engine through until you can determine that you can position the crankshaft so the piston is slightly after Top Dead Center between the compression and power strokes. Remove the valve cover and adjust the valves. The other guy gave you some settings but I like to set the intake clearance at .003 inch, the exhaust at .005 inch. Now that you have gotten the valve adjusted, slowly turn the engine through several revolution while you are watching the valves. You should see the intake valve open on a downward stroke of the piston and then as the piston begins it's upward stroke, when it is about halfway up this stroke you should see the intake valve bump off it's seat for a few degrees of crankshaft rotation and the re-seat. Then as you turn it farther you should see the exhaust vale open and then close. Then this whole sequence should repeat. If after adjusting the intake valve clearance, you DO NOT see the intake valve bump off it's seat when the piston is about halfway up the compression stroke, you have internal problems with the ACR cam/weight assembly. If this is the case, you will need to open the engine up. MOST of the ACR problem can be cured with a valve adjustment.


Kent

 

[guido]

Hello Kentb Of SWMO,
Here is a picture of a 4 cycle B&S compression release. The models covered by this design are at the top of the article.
Guido

 

[Kentb of SWMO]

I have not worked on these models of Briggs engine so I was mistaken on which vale the ACR acts on. The 14.5, 16.5 and 17 HP engine, I do not have the model numbers handy, Have the ACR on the intake valve lobe.

Kent