Too much compression??

[dart451]

Working on a Craftsman tractor, 917.287121 Briggs 31P977-0635-E. The owner bought a new battery cause the starter was dragging, didn't fix the problem. I installed a new starter, solenoid, same problem. I have bypassed the both negative and positive cables, same problem. It's like it gets on a compression stroke and struggles to turn over the motor. Once it starts spinning, it spins fine. I just checked the compression, I'm getting a max of 135-140 psi. Pretty high for an older tractor I would think. First thought was that gas was escaping into the crankcase...I've had that happen before. Oil level is perfect! Any thoughts from those in the know?

[38racing]

you did check valve clearance ? Compression release works on the intake valve. Won't work if too much clearance. Common on these briggs models.

[dart451]

Never heard of that 38racing! Didn't even know they had a compression release built in!?

[dart451]

Would .023 on intake and .25 on exhaust be too much? lmao The book says .003-.005 intake and .005-007 on exhaust! lol

[KE4AVB]

Also Note these camshaft ACRs on the 793880 do fail so you will not get the ACR bump just TDC compression if it has failed.

Most times it is valve adjustment that is off but not always.

[KE4AVB]

Would .023 on intake and .25 on exhaust be too much? lmao The book says .003-.005 intake and .005-007 on exhaust! lol

Could like the 44M I working on that the intake is over 6-1/4"

[dart451]

Well, you guys did it again! Starts right up with no drag at all! Where do I send the beer? lol