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1939 248 Rebuild step-by-step


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Hello Friends.

Found and bought a complete 1939 Buick 248 from a gentleman in Florida. While I've done basic engine maintenance over the years I've never attempted an engine rebuild. I would like to believe that someone at sometime has composed a comprehensive how-to guide for such a quest.

Anyone reading this aware of a source for or can provide a step-by-step guide for rebuilding a 248?


Thank you!


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  • 2 weeks later...


Here's the engine I bought in Florida.

I'm hoping that out of all the folks out there in the world who rebuilt a 248, someone recorded their experience and is willing to share same.





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There is two most important things to do.  First, replace the original oil pump with a new or rebuilt one from a 1941-53 248 or 263 engine.  The gears are larger.  (memory does not permit me to recall exactly how much larger)  In addition replace the bottom plate, if it is pot metal and replace it with one made of steel.  Buick put out a kit with a new steel bottom plate and separate neck.  The original bottom plates would warp (belly) and cause loss of oil pressure.  In addition, do not reinstall babbit rod bearings.  The 1950 series 40 (only) had insert bearings that retrofit to 1937-1949 248 engines.  If you can't find rods you can have the old ones re-machined to accept the insert bearings.  However, your machinist has to be very good and the rods have to be weighed before use.  In fact, it is a mistake not to have the engine balanced after being rebuilt, if there is a machine shop anywhere around who can balance a straight 8 crankshaft, assuming you have to turn the crank.  After that it is pretty straight-forward.  Make sure the machine shop also weighs the new pistons, again assuming they will bore the cylinders to true them up.  Rings are available in the various sizes, i.e. .010 oversize or .020 oversize.  You can go to .030 oversize as I did on one of my '39 Specials, but only do that if you have to to clean up the cylinder.  These Buicks were famous for the rings breaking in little pieces, turning and breaking out the ring lances and scoring the cylinder walls.  This happened to my car and why I had to go to .030 o/s.  This is more likely to happen if the car had a simple ring job years ago and especially if the nuroulized (sp?) the pistons at that time.

Edited by Dynaflash8 (see edit history)
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