Spark plugs with 3/16 x 40 thread.

[Bruno Mueller]

Guys, I am looking for a delivery address for spark plugs with 3/16 x 40 thread.

 

[stevehuckss396]

Same as #10-40. Rimfires are out there somewhere. I think the Chinese are making them now also.

 

[SmithDoor]

Guys, I am looking for a delivery address for spark plugs with 3/16 x 40 thread.

Try Ebay
It hard one use model engines in 1930 to late 1950’s. The it was all glow plug with think is a odd size ¼" . There maybe 3/16" glow plug that with some work could be a spark plug.

It can be hard one to find

I would try what

stevehuckss396
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Today at 5:17 PM
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#2
Same as #10-40. Rimfires are out there somewhere. I think

and modify to fit.

Dave

 

[Bruno Mueller]

I can see that it will be difficult to get spark plugs of this type. I may drill out the spark plug thread and cut 1/4 x 32 threads. However, I still have a question about this. Does this thread have a flank angle of 60° or 55°?

 

[gbritnell]

60 degrees. 55 I believe is Whitworth

 

[SmithDoor]

I can see that it will be difficult to get spark plugs of this type. I may drill out the spark plug thread and cut 1/4 x 32 threads. However, I still have a question about this. Does this thread have a flank angle of 60° or 55°?

Where I live everthing is 60° unless it was made in the UK then bring out the dies .

I would check the plug

Dave

 

[SmithDoor]

Guys, I am looking for a delivery address for spark plugs with 3/16 x 40 thread.

To see if 55° or 60° I like using this a pocket comparator. I have a 10X and about 6 disk only two I use.
The first has both 55° and 60°.
I only use this for threads on old British equipment and engines.

Dave

 

[stevehuckss396]

3/16 = .188
#10 = .190
Both 40tpi

#10 and 3/16 are basically the same thing. What am I missing? Why would you open it up to 1/4 inch? Just get a 10-40 plug.

 

[SmithDoor]

3/16 = .188
#10 = .190
Both 40tpi

#10 and 3/16 are basically the same thing. What am I missing? Why would you open it up to 1/4 inch? Just get a 10-40 plug.

I find and have plug in hand first then work out threading problem.

I was shown a model engine that use a brass insert in a aluminum head. The guy had this engine cross thread plug in and need a replacement. At time I was new to machine work to help him.

Dave

 

[BobsModels]

Hi
not sure if they still have them but check out this site, I got several of them when I built my Gade, the different types are shown if you click on side menu:

https://sparkplugs.morrisonandmarvin.com/order.php

Bob

 

[SmithDoor]

Hi
not sure if they still have them but check out this site, I got several of them when I built my Gade, the different types are shown if you click on side menu:

https://sparkplugs.morrisonandmarvin.com/order.php

Bob

Looks great.

Thank you
Dave

 

[Bruno Mueller]

I ordered two of these small mini spark plugs today.
I hope they are the right ones.
The spark plug is needed for this model.

https://de.aliexpress.com/item/1005...st_main.4.21ef5c5fkDQLbj&gatewayAdapt=glo2deu

 

[Bruno Mueller]

But It's nice to be a Prussian.
But it's better to be a Bavarian.
But It's the best to be a Rheinhesse.

 

[Bruno Mueller]

I have given the tiny thing a pulley. Now I can also start it with a cord.

 

[stevehuckss396]

That's

 

[BobsModels]

Dave
you have a plug in there could we see a picture of it out and the measurement of the thread length?

Bob

 

[Bruno Mueller]

Dave
you have a plug in there could we see a picture of it out and the measurement of the thread length?

Bob

Hello Dave,
I don't understand your question. Which plug do you mean?

 

[BobsModels]

Bruno

In post 12 and 14 you have a picture of an engine and it has a spark plug, I assume that is the plug you are looking for otherwise I do not understand the photo's. I would like to see the plug so as to determine the thread length you need, ie measure it. The 10-40 plugs come in short reach and long reach (maybe an in between) depends on the head of your engine. By showing a picture of it along with a ruler showing the length of the thread, we can better understand what you need. I agree with Steve I see no reason to change the threads.
Bob

 

[Bruno Mueller]

I hope the pictures say more than a thousand words.
The thread lengths of the two spark plugs are identical.

 

[Bruno Mueller]

I've ordered two of these spark plugs from the Chinaman, I'm looking forward to seeing how long they have to swim before I get them.
The smaller the spark plugs become, the more costly they are. For 2 pieces ~ 36,-€.