[DeTomaso] water pump mounting hole repair

Doug Braun doug at silicondesigns.com
Wed Jun 2 13:06:54 EDT 2010


In my younger days (30 years ago), one of the water pump bolt holes in my
block stripped out. Back in those days, I hadn't even heard of heli-coils
so I did a backyard fix by drilling and tapping the errant 5/16-NC-18 hole
out
to 3/8-NC16.  I then drilled out the corresponding hole in the water pump
to 3/8, installed a very non-stock looking 3/8 bolt and went merrily on my
way.

Fast-forward to now and I'm using the same block in a car that will be
concours judged. The water pump I'll be using is an original, unmolested,
"D0OE-D" 1970 water pump and I don't want to destroy it's value by drilling
out one of it's holes to 3/8 in order to use it.  So I'm looking for an
alternative.

Since the heli-coil approach is no longer viable, I'm considering using
either a 90259A139 or 92070A120 threaded insert from McMaster-Carr
http://www.mcmaster.com/

The hole in question can be seen here:
http://www.poca.com/index.php/gallery/?g2_itemId=21099
and is the one near the center of the picture next to right side of the cam
sprocket.  After tapping the hole to 7/16-NC14, the block will have about a
0.13" margin of cast iron block material left at the lower left quadrant of
the hole and a greater margin than that for the other 3 quadrants.

Does anyone see a risk in using this approach? Is one of the two threaded
inserts I referred to above superior to the other in this application?

Doug Braun, blue 73L #5505





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