[Charles Reese]

Originally Posted by Tom Wesenberg

Charles, did you mean to say "hex head" rather than "fillister head"? I don't recall ever seeing fillister head on engine side pans.

Hmmmm …. On boy! Me thinks I’ve open a can of worms (bolts/nuts)!!!
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As an aside, I found a typo in my original entry: A21666 Engine pan to frame bolt (should read NUT) (thick head, square) … slight chamfer on top face of nut: 1/4”-20 (3/16”t x 1/2”) …{plain}.
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My original engine pans (Jan 28 vehicle) were secured with the hex head bolts (w/ chamfered edges and cotter hole) I showed earlier in this thread … that doesn’t make it right, just what I found.
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The info I posted is from Mick Isbell’s Hardware Manuel:
* A-20553 1/4-28 x 9/16 fillister head screw (8 needed)
-- notation “deleted Dec 1929”
-- in retrospect, it makes no sense that this would be a ‘fillister head’ … this may be an example of the transposition of data in the Manual that has been discussed on FB previously. My apologies for leading us astray!!
* A-20534 1/4-28 x 1/2 bolt
-- no mention of cotter hole
-- presumably, this was after Dec ’29 and may have coincided with the change in the mounting of the pan at the front cross member
* A-21666 1/4-20 (3/16 x 1/2) square nut
?? notice that the bolt is 28 thread; the nut 20 thread {typo?}
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The 1-1-28 PPL & 10-1-28 PPL shows:
*A-20553 1/4-28 SAE x 9/16 square head bolt with cotter hole (8 needed)
-- this conflicts with the unique hex-head bolts which I believe were original to my vehicle
* A-21666 1/4-20 SAE (3/16 x 1/2) square nut (6 needed)
?? notice that the bolt is 28 thread; the nut 20 thread {typo?}
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I dont have the various PPLs between these dates ...
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The 7-1-31 PPL shows:
* A-20553 & cotter apparently obsoleted by now
* A-20534 1/4-28 x 1/2 hex head bolt (no mention of cotter hole)
* A-21666 1/4-20 (3/16 x 1/2) square nut
* A-22150 lock washer
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