Engine wont turn over. too much compression. ehaust valve is opening. new starter and battery.take out plug and it will start. put back in , nothing

Put your brand new battery on a battery charger. Many places don't look after them in storage. It may have the volts, but not the amps. Also make sure the battery contacts and leads are shiny bright using a wire brush, and smear Vaseline on them.

Very can be if it is an OHV engine that either the valves are needing adjusting or the decompressor has failed.

Most 4 cycle small mower engines have decompressors to help with the starting, These are only active at start-up and does not effect normal engine compression when running.

starter or battery not sufficient capacity to crank the engine fast enough under compression

Now it's time to become the gearhead in you and get this critter moving. The engine needs fuel, compression, and ignition (spark) to run. You must have heard the steady whuff, whuff, whuff of the cylinders pushing air out the sparkplug holes when you cranked it over with the plugs out, right? That was a good test of compression, if nothing else. Now look down the carburetor throat (with air cleaner removed) and operate the throttle with your hand. Does gas squirt down when you open the throttle plates. If it does, you know the engine is getting gas. The next thing is to check your ignition system-start at the spark plug and check for spark.-your '76 is heavenly simple compared to later models-but a good place to learn the basics. Still, I'd recommend buying a Haynes or Chilton repair manual for your truck. It can lead you step-by-step through any procedure you want to try, including the very problem you are having. .
Good luck.

Sometimes on the Briggs and Kohler engines, the compression release fails to operate at the proper time or is malfunctioning. A remedy for this is to remove the valve cover(s) and adjust the OH valves per the manufacturers specifications. This enables much easier starting, produces less wear and tear on the starter and may allow your new battery to completely turn that engine over. Out of adjustment valves mimic a weak or failing battery quite well and the engine hangs up on the compression stroke because the compression release system is not working properly. Adjust those darn valves.

If the engine is turning over too slow, the engine will not start. Try either charging the battery first or attach a charger while starting. If it is still turning slow, the starter may be drawing too many amps and need to be replaced.

Faulty MAP or MAF sensor, EGR valve stuck open, spark plug wires don't match firing order, large vacuum leak to intake manifold, very dirty fuel injectors, idle air control valve defective, poor compression in cylinders due to incorrect valve timing or leaking fuel injector o-ring seals.

It sounds like a starter problem. If the starter was used heavily -long runs or multiple times to start the engine- it could be shorted. Overheating is the enemy of the starters and happens when a starter is used hard to start a balky engine. Repalcing the starter isn't a big job and many B&S engines use the same starter. Find a working starter, replace yours with it and try to start the engine (with clean plug and full battery.)

It is also very possible that the compression relief valve is malfunctioning. It s mounted on the cam shaft and opens the exhaust valve to bleed compression from the cylinder(s) when starting. When it doesn't hold the valve open the starter can't throw the cylinder past top dead center TDC) to relieve compression. The work around is this: turning the pulley manually past TDC will allow a good starter and fully charged battery and clean plug to turn the engine and fire.

B&S has a high failure rate for the compression relief valve and states that the valve clearances are critical for the valve to function properly. And when the engine is worn and valve clearances are set right but it still malfunctions... the company has various reasons why YOU caused the problem.

Replacing the compression relief valve etc takes 3-5 hours and at $65+/hr you can see what the cost is- not including the relief valve which costs somewhere around a $100 (more for larger engines.) Even after replacement, it might not fix the problem.

You likely need to get the valves adjusted,it sounds like the decompressor is not working.You need to get the compression down to 130 lbs while cranking or the starter can't overcome the compression.Try turning the motor past the compression stroke by hand and see if it will crank faster,if so then the decompressor is out of adjustment.If the decompressor is not just a lob on the valves then you need to call the repair depot for craftsman and find out what you need to do to fix the problem.If none of the above works then you may need a battery,or just clean the cables and battery posts.

Have the battery tested at an auto parts store to ensure there is enough power in it. Sounds like it's strong enough to turn the motor with no compression (spark plug removed) but too weak to turn the motor with compression. Also check for loose or corroded wires.