Solving Delco Main Bearing Problems

By Staff
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On left, old Delco bearing with inner and outer races. On right, new bearing with inner race and new doughnut filler bushing.

4001 Fox Run Road, Powhatan, Virginia 23139

I have several Delco one cylinder, 32-volt light plants which I
have been wanting to restore. They all seem to have a common
problem with the main bearings. Invariably, the ones I have found
have been discarded and exposed to the weather for many years, and
of course, have filled with rain water. This, I have found, seems
to enter the engine and follow the valve stems down to the
crankcase, settling beneath the oil and building usually to a depth
equal to or greater than the main bearings. At this point some
water and oil may seep outside around the main bearings, but by now
the damage has been done. The steel roller bearings are almost
always pitted and ruined beyond use, and the worst part is that the
races or bearings are no longer available today.

So, after some time looking at all these engines with their
parts lying about, an idea struck me. Why not use a different
bearing (heavy enough to carry the load, but not physically
smaller), and construct a doughnut spacer of steel to make up the
difference in size of the outer race? After checking again with
National Bearing in Richmond, Virginia, I found an inner race which
fit the shaft, with the same width as the old bearing. All I needed
to do now, was machine a doughnut filler to replace the outer race
and to make up the difference in size. Then, I allowed five
additional thousandths in diameter for a snug fit in the end bell.
(See photo).

Well, I picked up the bearings and inner race, made the spacer,
and I’m happy to say that this worked well and solved the
problem. The Delco engines are finally going back together again,
at least until the next problem arises!

This technique of adapting bearings by using spacers might prove
useful on other machinery as well. If you need to order the
bearings mentioned above, I purchased mine from American Bearing,
(804) 353-4407. The part numbers are: bearing HRBC SRF55 and inner
race HRBC IR 7275C.

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