Small Engines (Lawn Mowers, etc.): hard to start Briggs engine, rubber insulation, old ford

Question
Hi and thanks in advance for providing this service.  I have a Briggs engine 31P777-0293-E2 that has become increasingly hard to start.  It seems to have a hard time passing the compression at TDC. The flywheel will spin once or twice, but can't keep up momentum to start. I resorted to jumping with my truck, but it has become hard to even do that, especially when it is below 45 degrees.  I have installed a new battery which will hesitantly start the motor if it is warm enough, but when the starting is hard, the battery weakens and has to be brought to full charge for a new start. I have adjusted the valves as per your instructions that I have read in your advice to others. I have checked the solenoid with a voltmeter(seems to be okay) and I have tested the voltage of the battery while running to test the charging system(also seems okay).  With the spark plug removed the starter turns fine and the flywheel spins freely. Once started the motor runs perfectly, but it is just so hard to start. I am wondering about the ACR but would like your advice on what else should be checked before open up the engine.

Answer
How old is the mower?  Snapper had a problem similar to the one you described years ago.  To test, you would need a DC shut to check how much current (amps) is moving through the wires.

The Snapper issue turned out to be too small of wires...could not carry enough current to turn the engine...and this was a brand new mower right out of the crate.

I've seen this same problem once on an old Ford starter.  We replaced the starter, battery, dis-connected and cleaned every connection with a wirebrush and still had the same problem.  We ended up measuring the voltage drop and found a bad cable...too much resistance built up inside the rubber insulation overtime.  

You could try measuring the voltage drop across the various cables as this would be a no cost test if you already have a voltmeter...just some research and time to learn how to measure voltage drop across a wire.

Or, you could replace the positive, negative and starter solenoid wires with heavier wires or run another wire in parallel to increase the current flow in the starter circuit.

As for the ACR they are very reliable as they are usually a mechanical grind on one of the canm lobes.  A few ACR's used a spring on the cam but not your engine.  Bottomline, if the valve clearances are correct the ACR should be working fine.  What are the valve clearances at TDC and 1/4 inch past TDC?

Eric