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Debating the Drag Pack - Radiator Support Holes

by Jeff Finley

This here is the hole truth and nothing but the hole truth so help me. . . somebody.
It has been thought that the holes in the radiator support allowing passage of the oil cooler lines were the tell tale sign of a factory oil cooler car. It was said the upper hole had to be a smooth, factory cut, oval. The lower oil cooler line hole should be round and should occur in the beveled area just above the lower oval A/C hole. The warning was if you saw any jagged holes or a simple rectangular upper hole that was formed by removing a knockout plate, beware, it's not a factory car. Recent research and photographic proof from Registry members has proven that this "old Mustanger's" tale just like other old Mustanger's tales isn't true. Never say never and never say all (or always).

Above: Hole thought to be the proper upper oil line hole on oil cooler cars.


Above: Original knock-out plate.

Let's go back in time to the year 1967. Shown to the right is a scan of the Ford print for the 1967/1968 Mustang radiator support. Why 1967/68 you ask? There were no oil coolers on those cars. Yes, that's right. Look at the drawing. You will see the familiar "look" of an oval hole. You see the note in the upper right side pointing to the oval hole? It reads, "2 DRILL DIMPLES 1.50 DIA. FOR A/C INSTALLATION." If this is supposed to be a clean, oval hole, why does it need two (2) drill dimples? Notice the other note, "LANCE THIS DISTANCE BOTH SIDES." That is to form the knock out. Also note the dimension, 1.74. and the .75R (radius) on the oval. 2 x .75 =1.50. Not a coincidence.

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Above: 1967/68 drawing

Moving on to 1969/1970. This is a scan of the 1969/70 radiator support drawing. Notice there's no oval hole. Well, there's no oval hole shown on the drawing. There is, however, the same note in the lower left, "2 DRILL DIMPLES 1.50 DIA. FOR A/C INSTALLATION." Look closely and you can see the two dimples. The arrow from the note points to the lower dimple. Look closely again and you will see an arrow pointing into the side of what looks like a square with the same dimension, 1.74. The line for that arrow goes off to a side note where it says. . . 69_70.jpg (151091 bytes)

Above: 1969/70 drawing


So, the 1969/70 drawing has the same notes and dimensions as the 1967/68 except for the oval hole. What about the hole? The 1967/68 drawing is probably technically incorrect because it depicts an oval hole which did not actually exist as the part was stamped at the stamping plant without the oval hole. Why put in the dimples and a drill note if you were going to stamp out the entire oval? The lancing formed the rectangular knockout.

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Above: 1969/70 drawing side note

With all that in mind, what the registry has found is that the upper "oval hole" was not a clean, stamped hole. How was it made? The oval hole was made by a 1.50" drill bit or hole saw centered on the dimples and done by an assembly worker. Two runs with a drill and knocking out the remaining material in the center between the holes created the oval hole. Trouble here is, there were humans involved. Where there are humans involved there will be errors. Not all oval holes are created equally. See the photos below from documented factory Drag Pack option cars. (BOSS 429, 428 SCJs and Cougars).

photos by Frank Bowers

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1969 BOSS 429 - top and bottom drilled off center

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1969 428 SCJ - missing top cut

belimtop.jpg (34871 bytes) 1970 Cougar Eliminator - not quite complete
"Okay, there is a round hole on the slanted surface just above the lower oval hole. When you see that round hole, you know it came from the factory with an oil cooler."  Look back up at the 1969/70 print scan. See the ellipse cut in half at the bottom? You remember your geometry, right? A circle shown in a slanted view becomes an ellipse, right?
Here is another view of that same hole. If you look closely you can see Section P is cut through this hole.

Right: 1969/70 drawing lower portion

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Here is Section P shown in another location on the print showing the true round hole. See the arrow coming in from the upper left?


Right: 1969/70 drawing lower round hole

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The note that arrow points from (to) says, "1.250 DIA HOLE DRILL AT ASSY FOR OIL LINE". ASSY is the Ford abbreviation for ASSEMBLY. The "BV" in the circle is a change notation. Change note BV shows this hole was added for the 1970 MY. You should not see this hole on a 1969 car. But remember, never say never.

So... this hole wasn't a round, stamped hole either. It too was drilled by a line worker.

Right: 1969/70 lower round hole note

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Jagged holes and radiator supports lacking holes have been found. Here again, there are humans involved and there will be "assembly variations."

photos by Frank Bowers

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Above: 1969 BOSS 429

Above right: 1970 Cougar Eliminator


Right: 1969 428 SCJ




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The whole truth is the holes in the radiator support don't mean a thing when comes to identifying a factory oil cooler car. The upper holes can be crooked or jagged or just the rectangle from the knock out. (Wonder how they knocked that out if they were supposed to drill it? Very creative line workers no doubt.) The lower hole can be perfectly round, rough and oblong or the lower oval might be extended from the drilling or the hole might not even be there at all. There may be holes in cars that were never intended to get an oil cooler. So the line workers drilled a few extra holes. Weight savings. Gets better gas mileage.

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This page last updated: January 27, 2013