Bethlehem 360 Spark Plugs

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Tadpole
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Bethlehem 360 Spark Plugs

Post by Tadpole » Wed Jun 22, 2022 2:57 pm

Does anyone have experience running these 360 one-point style plugs? Will they work in a T?
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Re: Bethlehem 360 Spark Plugs

Post by OldFord » Wed Jun 22, 2022 3:14 pm

Those particular plugs do not have 1/2" pipe thread. If you found bethlehem plugs with pipe thread, there is no reason the wouldn't work.

Frank

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Re: Bethlehem 360 Spark Plugs

Post by Tadpole » Wed Jun 22, 2022 3:29 pm

Mr. Iaccino, It doesn't look like the threads are tapered on these plugs but they measure 1/2". Does this mean they will not properly seal? Would a copper washer maybe help?

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Re: Bethlehem 360 Spark Plugs

Post by Steve Jelf » Wed Jun 22, 2022 4:22 pm

No, you need ½" pipe thread. It looks like this.

IMG_3544 copy.JPG
IMG_2515 copy.JPG
Notice the slight taper. It doesn't take washers.
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Re: Bethlehem 360 Spark Plugs

Post by OldFord » Sat Jun 25, 2022 8:08 am

The thread on those appears to be straight. If they measure approximately 1/2", they are most likely 14 mm. The threads will cross and not provide a proper seal....

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Re: Bethlehem 360 Spark Plugs

Post by TXGOAT2 » Sat Jun 25, 2022 8:47 am

A 1/2" male pipe thread measures 3/4" OD, or a little more.

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Re: Bethlehem 360 Spark Plugs

Post by Tadpole » Sat Jun 25, 2022 11:14 am

Thank you all for the input, I passed them up for the reasons you provided. But if anyone is still interested they are on T-bay for sale, six of them tested.

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Re: Bethlehem 360 Spark Plugs

Post by Tadpole » Wed Jan 25, 2023 9:42 am

I'm reviving this thread because I found more examples of this 1/2" straight thread plug NOS labeled "Ford Special". I bought them so I will test them out on a T, not sure what other kind of Ford applications there could be? It's trivial but fun to do these kinds of experiments.
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Re: Bethlehem 360 Spark Plugs

Post by speedytinc » Wed Jan 25, 2023 10:38 am

Cant read the thread on the label. If they are not 1/2 pipe thread, they wont work.
If you insist on trying them, leave the hood off & stand clear to start.


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Re: Bethlehem 360 Spark Plugs

Post by Art M » Wed Jan 25, 2023 10:56 am

Possibly, you could use an adapter that goes from 1/2 in pipe thread to 14 mm. Langs, Snyders and other vendors have them.

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Re: Bethlehem 360 Spark Plugs

Post by Steve Jelf » Wed Jan 25, 2023 11:05 am

Flathead Ford V8 plug threads are 14 mm x 1.25 pitch. Is that what these are?
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Re: Bethlehem 360 Spark Plugs

Post by TFan » Wed Jan 25, 2023 11:16 am

Model "A" possibly. JIm
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Re: Bethlehem 360 Spark Plugs

Post by Adam » Wed Jan 25, 2023 11:17 am

Anything with a flat shoulder at the top of the threads and a seal is not a pipe thread. If it says “Ford Special”, either that means “Model A”, or the wrong spark plugs are in the box.

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Re: Bethlehem 360 Spark Plugs

Post by RajoRacer » Wed Jan 25, 2023 11:27 am

Pretty sure Model A are 18mm or 7/8".

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Re: Bethlehem 360 Spark Plugs

Post by TRDxB2 » Wed Jan 25, 2023 12:17 pm

speedytinc wrote:
Wed Jan 25, 2023 10:38 am
Cant read the thread on the label. If they are not 1/2 pipe thread, they wont work.
If you insist on trying them, leave the hood off & stand clear to start.
ONE BOX says 1/2 doesn't mean the others are
beth.png
Discussion from an old thread not box colors are different
beth3.png
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beth2.png
By Donnie Brown North Central Arkansas on Monday, June 04, 2018 - 09:06 pm:
I tested the "fire ring" plug in a Model T head. The threads just fall into the hole and are a "sloppy fit" (hillbilly technical term). So they obviously do not fit a Model T
I did not have a metric thread gauge, but the thread count/pitch of the "fire ring" plug is between 16tpi and 18tpi. so I assume it has Metric threads. I measured the outside diameter of the threads to be 0.705.
That only leaves V-8 Ford and the early "letter" series cars, if these are to fit some Ford product. Maybe someone knows what the size of the V-8 plug or the "letter" series plugs are ?????
I think Dale is correct about them being motorcycle or aviation plugs.
Possibly there were several sets that were labeled wrong back in the day. That may be the reason of these surviving in their original boxes. Some dealer may have just stuck them on the top shelf and forgot about them when he found out they were incorrect and had no market to sell them to . ????
These may be super rare, but I probably will never know for sure what they fit. They do look nice with the other spark plugs I have.
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Re: Bethlehem 360 Spark Plugs

Post by Scott_Conger » Wed Jan 25, 2023 3:13 pm

per Donnie's measurements, those threads are m18 x 1.5

it is a perfectly standard 18mm spark plug.
Find an engine which takes 18mm plugs and knock yourself out.
A 1933-37 FORD should suffice.
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Re: Bethlehem 360 Spark Plugs

Post by Art M » Wed Jan 25, 2023 6:22 pm

I have that size tap in my ollection and now I k own why.

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Re: Bethlehem 360 Spark Plugs

Post by Scott_Conger » Wed Jan 25, 2023 9:32 pm

Art

old spark plugs and O2 sensors on modern cars.
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