Pan cover screws

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ratchet449mc
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Pan cover screws

#1

Post by ratchet449mc »

Hey everyone. Just had a set of 48 panheads restored and I'm looking for a source for 3/16x24 short allen heads..I don't want to use phillips. I'm aware that the originals had 3 aliens for each head, but I want to use them all the way around. Any help is greatly appreciated...Ratchet...
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Re: Pan cover screws

#2

Post by Bigincher »

ratchet449mc wrote:Hey everyone. Just had a set of 48 panheads restored and I'm looking for a source for 3/16x24 short allen heads..I don't want to use phillips. I'm aware that the originals had 3 aliens for each head, but I want to use them all the way around. Any help is greatly appreciated...Ratchet...
Do you have a Fastenal store in your area? That's where I would go for something like that.

https://www.fastenal.com/

Or get them from Old Dude, but you'll pay dearly for them.
ratchet449mc
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Re: Pan cover screws

#3

Post by ratchet449mc »

Thanks, Yeah got fastenal here. I'll try them and if no joy, I'll try one of the local machinery suppliers. Don at head hog redid them and told me they aren't 10-24, but 3/16x24 as per the factory. Hard thread to find. Damn well cut my own if I have to..lol
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Re: Pan cover screws

#4

Post by PanPal »

I thought they were hex head flanged bolts on all pan covers? No?
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Re: Pan cover screws

#5

Post by RUBONE »

10-24 screws are .0025 larger than 3/16-24, so slightly less in thickness than a human hair.

The hex head flanged screws are standard on cast D-Rings, early laminate rings used several different screw types and not all the same head type within the same year.
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Re: Pan cover screws

#6

Post by awander »

What Robbie said.

If you can find 10-24 more easily, go ahead and use them.

On the slight chance that the tapped holes are too tight, just run a 10-24 tap through them.
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Re: Pan cover screws

#7

Post by ratchet449mc »

Not.... These are freshly restored by HeadHog 1948 heads.. I spent a lot having these brought back to original and The last thing I'm going to do is start modifying them. Even something that minor...
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Re: Pan cover screws

#8

Post by awander »

ratchet449mc wrote:Not.... These are freshly restored by HeadHog 1948 heads.. I spent a lot having these brought back to original and The last thing I'm going to do is start modifying them. Even something that minor...
Well, of course, they are yours, and you should do as you wish.

But 2 and a half thousandths of an inch is not something you could even easily measure.

I'd bet a 10-24 screws right in.
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Re: Pan cover screws

#9

Post by RUBONE »

3/16-24 is basically a hardware store thread used for low grade fasteners and generally ended in the late '50s for industrial use. 10-24 is a machine screw used in industry up to this day. Most 3/16 fasteners are grade 3 or less. #10 fasteners come in up to grade eight. The 3/16 will work fine for Pan D-rings, however the head profiles available will be extremely limited.
OEM fasteners are pretty much extinct, so general purpose types will have to be used if you are keeping to the 3/16. And unless the tap used was very special my guess is that a #10 will screw right in.
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Re: Pan cover screws

#10

Post by Andygears »

I found this interesting because I had never heard of 3/16 - 24 thread! So I consulted my "Machinery Handbook", not my regular use 1994 edition, but my 1943 edition inherited from my dad. It shows no listing of 3/16-24, only 10 -24 in various classes of fit. Now perhaps the .0025 size difference to which he was referring is the difference in tolerance between a class 2 fit and a class 3 fit.
Since this is important to you here's the difference in the screws:
Class 2 fit : Pitch dia. 0.1596 to 0.1629
Class 3 fit : Pitch dia. 0.1605 to 0.1629
If you have a pitch mike you can check whichever screws you decide upon. I generally use McMaster Carr if I need to be sure about high quality hardware. They have selection which has military specs.
I, not being a purist went to 10-24 x 3/4 screws instead of the original 5/8. The gain is one more thread engaged in the head and the incomplete (often) first screw thread hangs below the head surface. Visibly wrong for AMCA judging. The single blind screw by the motor mount must be shortened to suit.
After spending hours fitting AM covers and d-rings, sanding all flat, installing screws and sealing gaskets in place, I removed each screw, cleaned it and locktited in place. Seems to work so far.

My two cents.
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Re: Pan cover screws

#11

Post by awander »

It's interesting-I looked in my Machinery's Handbooks back to 1914, and could find no mention of the 3/16-24 as a standard thread size in the USA. They had already gone to using Number Sizes for anything smaller than 1/4".

But you can still buy 3/16-24 bolts and screws today.

And Robbie was correct, the 3/16 Nominal Major Diameter is 0.1875", while for #10 it is 0.19", for a difference of 0.0025" (or two and a half thousandths of an inch).
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Re: Pan cover screws

#12

Post by Larry »

I can't find 3/16-24 in my Machinery Handbook or in my Harley parts manuals.
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Re: Pan cover screws

#13

Post by awander »

Larry wrote:I can't find 3/16-24 in my Machinery Handbook or in my Harley parts manuals.
I also find it interesting that the '41-'54 parts manual shows the screws (P/N 2675 for '48-'51; 2674 & 2678 for '51-'54) in the parts diagram/list section, but in the back where they list hardware sizes, only P/N 2674 is shown, and is listed simply as "Allen Head Screw", with no size info given.
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Re: Pan cover screws

#14

Post by PanPal »

I did a google search on the 3/16 thread and found a guy that had written this
I consulted my machinist hand book and the overall information of the 3/16-24 BSW (British Standard Whitworth) and the 10-24 UNC ( American unified coarse) are very close as listed above. The most important dimension is the pitch diameter. This is a line in the middle of the thread that is measured to determine if the thread is cut to size. Both of the threads mentioned have pitch diameters within the same . 005 of an inch range so should not have any interference issues and should be interchangeable almost all instances.
Never heard of 3/16-24 myself.
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Re: Pan cover screws

#15

Post by awander »

BSW is a different thread form than used in the US. It is a 55 degree included angle instead of the 60 degree we use here.

Depending on the tolerance the threads are made to, one may fit the other, but I wouldn't count on it.
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