white M3A1: correct spark plug reinforced cyl. head

[bing]

Hi,

I recently acquired a NOS cylinder head for my White M3A1 scout car.
It's in top condition, and aparently it's dated 9-8-47.
It holds the same patent numbers and AC mark as the original head which is not reinforced.
Only 2 notable differences:
- reinforcements similar to the popular DAF engine heads
- big *ss diameter spark plugs...

the later is what's troubeling me.
It came with 6 NOS Firestone spark plugs of which 1 is broken in 2 (something must have been dropped on it at some point)
The spark plugs still show some cosmoline wrap and cary the number: S-40-CF

The only problem now is, does anyone have a conversion table to Champion or NGK or something from nowadays?
Because I can't seem to find any replacements for it.

As an extra, has anyone ever had any experiences with these cylinder heads and/or big diameter spark plugs?

Thanks!
Erwin.

[Kim Sievert]

Plug sizes in 14mm, depend on if you install the RF shielding componets or do not use the RF shielding componets.
The plug sizes the manuals call out,,, like Champion #,,, the modern day plug with that number, is to tall to use with the plug RF shielding.
I found the right height size of plug, that is common to lawn mowers usage, fits great with the RF shielding.

[steveo916]

this guy has about 100 of the original plugs

http://cgi.ebay.com/ebaymotors/Fireston ... 500wt_1182" onclick="window.open(this.href);return false;

[algor]

Other spark plugs for hercules JXD, are available here:

http://cgi.ebay.com/ebaymotors/CHRYSLER ... ccessories" onclick="window.open(this.href);return false;

http://cgi.ebay.com/ebaymotors/NGK-3522 ... aleQ5fLots" onclick="window.open(this.href);return false;

http://cgi.ebay.com/CHAMPION-SPARK-PLUG ... 1e59586d63" onclick="window.open(this.href);return false;

In any case in accordance with SNL G67, the Scout Car uses two different types of spark plugs:

- 14 mm. Champion J-10 (Lots 1 through 4)
- Champion JC-10-64C (engine Lots 5 and up)

Alberto

[scoutcarM3A1]

Hello,

Does this mean that the regular sparks type Champion C8J (hope got the right configuration!) used on a lot of WWII vehicles would not work properly on SC??

Rudy

[bing]

Thanks for the replies guys,

I know a guy who has the shielded versions for sale, so I'll have a look to see if those are the ones that would fit. Just a wild guess, but the regular 14mm spark plugs will probably fit in the shields?

Otherwise I'll order some from the ebay link, as those are the exact same ones that were in it.
They measure almost 20 mm in diameter.
If anyone would have any cross reference to any other spark plug make for a Firestone S-40-CF plug that would be very welcome anyway.

I tried looking for the Champion make spark plug for engine lots 5 and higher, but could not find anything about it. My guess is this is not a current number any more.

I'll get some pictures and measurements up as soon as I get the chance, and keep you posted on the solution.
I'm probably going to look for some busses you can put in the holes to make them take the regular 14mm spark plug if the shielded versions don't work.

Thanks!
Erwin.

[bing]

Hello,

Does this mean that the regular sparks type Champion C8J (hope got the right configuration!) used on a lot of WWII vehicles would not work properly on SC??

Rudy

Hi Rudy,

someone told me to check the spark plugs after a while to see if they are too hot/cold.
Usually the lower the number the hotter the spark plug and the higher the number, the colder.
I'm not completely sure anymore, but if I remember it right:
If the ignitor at the bottom is bent after driving for a while, the plug is too cold, this can't cause too much harm to the engine though
if it looks really dark like burnt, the plug is too hot and will eventually cause a hole in the piston as the spark always hits it in the same spot and weakens it...

Again, a pro should check this out again first as I'm not 100% sure anymore if this was the correct way to see it.

regards,
Erwin.

[algor]

does anyone have a conversion table to Champion or NGK or something from nowadays?

Here you find a conversion table for different spark plugs manufacturers:

http://www.rpw.it/Files/Tabella_compara ... andele.pdf" onclick="window.open(this.href);return false;

Alberto

[bing]

Thanks Alberto,

but there's the same problem with all current conversion tables.
They don't cary old spark plugs like the Firestone S-40-CF.
In fact, I haven't found any yet which hold Firestone conversions...

Nevertheless, this could help out other people though!
Thanks for trying.
Erwin.

[Kim Sievert]

If you can, take a photo of the head and of the plugs and post them.
My bad,,,, I did not pick up the fact, (that in the original posting), that the plugs were bigger than normal 14mm.
From what I know, the Hercules JX series of engines, were in production from 1935 to 1975.
I believe in MVPA supply line, there is an ad from a company that has parts, for the Hercules Motors.
That person also sells on Ebay.

Kim

[bing]

Hi,

update on the spark plugs.
Got the pictures on my computer at home, so I'll try to get them online asap.
However, can't do this from here.

I found some interesting links on the internet to companies that actually produce adapters for the 22mm (7/8") spark plugs, so you can put regular 14mm in them.
http://www.sparkplugadapters.com/services.html
http://www.gsparkplug.com/shop/spark-pl ... -14mm.html

The first website gives you the choice between steel and brass. I thought steel would be better to withstand the heat of the cylinder head, but brass ones are more expensive, so there's not much logic in that... anyone got any experience with this?

In my search for extra spark plugs, I tried a supplier nearby, but they only have NGK plugs and those are only made in 14mm and 18mm threads... still too small.

Finally, I was able to find a match in Champion spark plugs using the thread and hex sizes to match:
http://www.sparkplugs.com/product.aspx?zpid=26089
The Champion W14 spark plugs shows the exact same sizes as the original firestone and is still being produced.
The champion websites furthermore indicates them as being used in various industrial motors and vehicles (tractors, lift trucks) that have a Hercules JXD as their power unit:
Davey, Worthington, Cleveland, Galion, Ross

This indicates that the cylinder head in question would be used in rather stationary engines as I first thought.

So for the time being I'll get it up and running on the original Firestone spark plugs (got 6 good ones now), but will change to the Champion W14's as soon as they arrive.
Other than that, i would still consider the use of adapters as that would make it easier to find spark plugs during a breakdown... However they would need to be a bit longer because of the nut on top of the adapter.

I also measured the original head and the reinforced head. The compression chambers are a bit deeper on it, but then again I haven't got any records on how many times the original one has been flattened/scraped (not sure what the correct word in english would be). It will result in a little less compression and power, but then again I'd rather have a little less power than to not being able to drive it at all )

Getting pictures up soon.

Erwin.

[snooopy]

I believe that the larger (18mm) spark plugs were used in stationary engines.... in things like welders and the Sperry searchlight...as I have a NOS 18mm plug in a 1941 dated Sperry packet. I have a NOS engine with the normal head...i.e. no reinforcing ribs, with the standard 14mm plugs. Also a NOS head WITH THE REINFORCING....AGAIN with 14mm plugs. Keep up with the research mate!

[bing]

Hi Snoopy,

that would mean there were 3 different types of spark plugs being used...
The regular 14mm,
your cyl. head with 18mm
and my cyl. head 22mm

interesting...

Anyway as promised, the photos of the head and spark plugs.







cheers from overseas,
Erwin.

[Kim Sievert]

Found this Spark Plug chart in a Diamond T Service manual.
Has plug #s for both 14mm and 18mm and their heat ranges.

[Jack Morrison]

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