Motor Swap ?

[Ciltech]

Anyone familar with crossing over Briggs & Stratton motors? Replacing a locked motor on a zero turn mower.
Needing to know if a B&S 33S877-0019-G1 would be a good crossover for replacing a 31E777- 0136-B1.
I want to stay with a pressure-oiled system.
Looking at the specs on the Briggs site for each motor I can't see any particular difference, other than CC size. Cable placement, fuel line placement, etc. all appear to be the same. Buying new so at that price I want to be sure the first time.
No looking to change to different brand motor, or rebuild the current one.
Minor hookup changes aren't a problem, I've done enough automotive mods over the years, so changing a few minor items around isn't an issue.

 

[bertsmobile1]

It should drop strait in
There may be different alternators & regulators but they will swap over from one engine to the other mounting centres are universal
Short block castings are all the same so every thing from one will swap to the other but you may need to tap a hole or two if the control plates are different to swap old to new
Fans & engine covers do vary
buy new engine mounting bolts , thread the holes about 3/4 before you pop the engine in because you will not be able to start the self tappers unless you strap the engine down
I like to use a little ( note little ) nickel anti sieze on the bolts.
Flanged bolts with teeth on the bottom loose their gripping power because the sharp edges on the teeth round over when undone .

 

[Ciltech]

This will be a 'drop-in' replacement as there are not covers, fans, etc to mount. Want to replace complete engine. But your tip on tapping is understood, I have a machinist training background.
Thanks, R.

 

[bertsmobile1]

Took me a couple of mouth fulls of alloy chips laying under a mower before it dawned on me that I should start the threads before I drop the engine in.
Then a couple of loose fits because the self tappers are not quite the same as a proper UNC thread before I twigged to only 1/2 to 2/3 threading the holes
I learn eventually and as luck would happen I have a lot of aluminium electrical wire I salvaged for the scrap and it comes in really handy to fix loose threads .