Small Engines (Lawn Mowers, etc.): 402707 Briggs engine, vertical shaft, dot marks

Question
I have been rebuilding a 16hp opposed twin Briggs engine on an old Murray law mower. When i put it all together, the crank will not turn. Leave block bolts 1/4 turn loose and it spins like well oiled machine.

All original parts, just cleaned. Pistons and rings replaced but removedfor trouble shooting. Valve springs off for trouble shooting... I did replace bushing at top

Of shaft in block and seal on top and bottom where crank goes through. Timing gear was upside down and turned right. Thanks for your help.

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Answer
Hi  Paul  


Paul here ,  can you give me more detail  ie  type number from engine covers  
we know its 402707  but need  type   numbers and date code  

the 1st  set of numbers  indicate

40 cubic inch ,  
2 = design series   --    
7= vertical shaft , flojet carb , pnuematic or mechanical governor.     
0 = plain bearing ,non flange mount  
7= electric start 12 v with alternator


did the unit rotate free before replacing pistons / rings  and bushings at top ?

did you make sure the notches on  both pistons  face the flywheel side  ?
did you align the dot  marks on cam gear  and the crank pinion  for cam timming ?

could be a crankshaft end play  problem  , if shim on end of crank is to thick and wrong gasket is use on sunp cover  crank will go tight when tightned up  cover may well be pressing up hard against crank/ shim  

try a thinner shim on crank ,  or a thicker gasket on sump  

here is website for manual to download ,got  manuals  section   once you have typed in
model and type codes from you engine , let it load , then save a copy  

www.briggsandstratton.com


get back to me  and i will help further


cheers  paul