MTFCA Forum

I'm fairly new to model T's and have had lots of fun putting noisemakers on my '24.

I'm trying to learn about the whistle spark plugs.

I see many of the whistle portion of the assembly available. but not the plugs themselves.

teach me about the spark plugs.

I would assume these are specially built plugs, and as usual they are a wear part.

I would like to install one on my car.

but I would prefer not to drill into my head to install just the whistle part.

What is the lifespan of the dedicated plugs? ARE there a plethora of them sitting on the shelf at NAPA?

Can current plugs be modified?

Believe you mean an “explosion whistle”.

Those devices for a T have a 1/2” pipe thread base, which has tapped opening to place any 1/2” pipe thread Spark plug. The spark plug does the ignition fire.

The whistle cylinder then carries gases of compression to make the sound, activated by the lever valve via pull chain. The spark plug and whistle component are separate.

DanTreace wrote: ↑

Thu Jul 24, 2025 5:01 pm

Believe you mean an “explosion whistle”.

Those devices for a T have a 1/2” pipe thread base, which has tapped opening to place any 1/2” pipe thread Spark plug. The spark plug does the ignition fire.

The whistle cylinder then carries gases of compression to make the sound, activated by the lever valve via pull chain. The spark plug and whistle component are separate.




IMG_9440.jpeg

Yes that's the one.

I see lots of the whistles for sale but not the plugs.

Any spark plug can be used. Isn’t a need for a custom spark plug. Fit any brand you wish as long as the threads of the plug fit the opening in the whistle.

Remove the existing plug. Install the whistle. Put the old plug in the adapter. There is no special plug.
FWIW, I have tried to run these types of whistles in my different T's, all the motors developed a rough running like miss.
So off they went. I have gotten similar feedback from a few other guys.

Haven't used an explosion whistle, and for that matter an 1/2" adapter in the cylinder head to install mm plugs.

IMO, it may be helpful to use a 'long reach' plug to get the electrode at least partially in the chamber.

Here is view of chamber with a standard reach plug.


The explosion whistle might be best done with a long reach, like the pretty green Splitdorf early plugs, note this collection shows these plugs with explosion whistles.

ahh... it's all making sense.

I had seen plugs specifically for the whistle that don't use the adapter...

like these....(pic stolen from a recent thread here) and that's what "sparked" my interest.





I had not seen the adapter before, but it looks like it is available from at least one of our regular dealers.

I do believe i would try to find some long reach plugs if I were to keep it on the car permanently, or find a few of the dedicated plugs -OR- try to find some long reach with the adapter.

I would imagine I'm reducing compression AND placing the spark in a less than ideal location for regular driving.... so not ideal.

It may be something I install for parades only....

I used one for parades only. I usually had to take the valve apart and clean and re-seat every couple of uses. I finally decided it wasn't worth the trouble and sold it at a swap meet.

Willy, the plugs that were specifically altered for the whistles keep the spark inside the combustion chamber where it belongs, better than the adaptors that were later made. These plugs were mostly (if not all) Splitdorfs altered and sold by Buell to go with their whistles. They are pretty scarce but not impossible to find, I’ve been collecting plugs for three years now and have acquired four. Only one of which fits a T. They were made from the late teens to early twenties. Most of these old plugs will last forever though if treated with care, occasional cleaning, and a spark that isn’t so intense as to cause heavy wear to the electrode.

With a welder, drill and some tubing I imagine one wouldn’t be too hard to make out of a Champion X, if you had the patience.

I like the idea of using a long reach plug with the adapter. I tried that once with a long reach Splitdorf but it wouldn’t fit all the way through the adapter, even when I bored the adapter out some. But there are many long reach plugs out there.

Also, if you find usable Splitdorfs, they must be cleaned by hand with gasoline or some other solvent (I’ve found gasoline to work well, and it was frequently recommended for cleaning plugs during the period. Likely because it was on hand anywhere automobiles were and will cut the carbon.). DO NOT use conventional pneumatic spark plug cleaners on mica insulated plugs. The mica sheets are resistant to heat and do not crack or shatter as porcelain does, but the sheeting is thin, brittle and flaky to the touch, especially after excessive wear. These are tough old plugs and resist dropping/cracking (a big selling feature at the time), but the mica is like paper and a wire brush or grit from a pneumatic cleaner will ruin one.

I did find a couple older threads here and while some poo poo the idea, I also found where somebunny said they had one installed with no issues for 50 years, and sumbunny else blamed a crankshaft break on one...


I like to fiddle around enough that I think it will be a fun toy.....

it looks like the whistle itself is the easiest part to find, so can be patient.


by the way, I have... so far...

1) the factory horn

2) a bermuda bell

3) an aermore train whistle

4) a wolf whistle

and I put a non-factory pin stripe on my wheels... so irreverent...

the cutout for the aermore, has been a royal pain, but I'm not deterred.... still working on fixing it's perpetual leak...

I'm enjoying my car immensely...

All that stuff will make your car reel Kool, and wheel pinstripes have been proven to increase acceleration.

I'm enjoying my car immensely...

And that makes it all worth while

Remember, as you fine tune your car - 'If it works for you - Then it works'

I have an adapter style 'explosion plug'. It is great fun for parades - the faster the engine runs the louder the noise. When you 'pull the chain' you do notice a bit of a drop in engine power while they are chirping.

Considerations:

I found they tend to work loose over (a not very long) time. Nuisance value in regular tightening.

They can make the engine run a little rougher (especially when they are loose) and need more than usual cleaning (plugs carbon up quicker).

I have not really noticed any marked loss of power when running with them in place (when not in use 'sounding').

My solution - put them in for displays/ parades, then whip then out for 'normal running'.

I think I’ll hold out for a splitdorf plug or two, depending on the going rate…

The adapter should be under $20 including shipping if the splitdorf is too expensive.

Just bought this on the ebays for $85 shipped…

The seller says the valve actuates, so I should be a leather washer away from functioning….




I’ll place an wanted add here for the splitdorf…


Is that spelled right?

I will also ask for the adapter and long reach plug if anyone has spares of either.

I call the explosion whistle in the picture that Dan posted - a crankshaft breaker. Back in ‘76 during the Colorado centennial tour I was a 26 year old kid with an explosion whistle on a T. I loved its ‘chortle’ sound when actuated going down an incline road. When ascending a Rocky Mountain road the actuated singular loud whistle could be heard for miles. This was when my crankshaft broke. My forensic determination was that cylinder explosive power was stolen from the T’s forward momentum and assigned to this damn “hey look at me” device causing engine carnage. I threw the explosion whistle away.

Steve Jelf wrote: ↑

Thu Jul 24, 2025 5:14 pm

I can imagine myself using an exhaust whistle, but not this. I want four good spark plugs, intact and well-adjusted. Brand doesn't matter. Champion X, Wards, Splitdorf, Horseshoe, whatever.

I agree 100%.

WillyR wrote: ↑

Thu Jul 24, 2025 11:06 pm

I will also ask for the adapter and long reach plug if anyone has spares of either.

I just found one in my stash.

big2bird wrote: ↑

Fri Jul 25, 2025 5:14 pm

WillyR wrote: ↑

Thu Jul 24, 2025 11:06 pm

I will also ask for the adapter and long reach plug if anyone has spares of either.

I just found one in my stash.

20250725_141456.jpg

Yeah, that looks like the adapter..

I'll place an ad here for the buell plug or the long reach plug/adapter....

I thank you all for your knowledge,

too bad J.C. Whitney isn't around, I'd probably order every damn gadget and gizmo they ever had for a model T....

A Model A or other Oooga horn will draw j ust as much attention as a compression whistle, except for the earlier cars without a battery. I had one on one of my cars but didn't like the shaking of the car. I live in the hills where I need every ounce of power the engine will deliver. Also not sure it is good for the crankshaft to jerk like a misfire whenever the whistle is used. The exhaust whistle or wolf whistle is a better option.
Norm

Norman Kling wrote: ↑

Mon Jul 28, 2025 11:29 am

A Model A or other Oooga horn will draw j ust as much attention as a compression whistle, except for the earlier cars without a battery. I had one on one of my cars but didn't like the shaking of the car. I live in the hills where I need every ounce of power the engine will deliver. Also not sure it is good for the crankshaft to jerk like a misfire whenever the whistle is used. The exhaust whistle or wolf whistle is a better option.
Norm

Odd as it may seem, I don't think I want a model A horn on this T, I do also like the push horn on the T roadster cars, but I think I may just get a model A (or 40) and either a roadster pickup or a touring with the push horn.

I have everything to hopefully fix the leaky cutout for the train whistle, but I wasn't motivated to take the car out of circulation this weekend to fix it. (had errands to run)

So far the exhaust whistle sounds great on a long downhill. too high on the rpm's and it's just shrill with no redeeming qualities.....

The wolf of course only sounds good at low idle, due to the engine vacuum.

I'll figure out where the explosion whistle sounds best..

the stock horn and the Bermuda bell sound in any situation....

"With a welder, drill and some tubing I imagine one wouldn’t be too hard to make out of a Champion X" Credit to Tadpole.
There is the solution.
Spark plugs with the outlet built in are quite rare & big $$. A matching set with one with the outlet built in, like the splitdorfs are mega $$$
Using the adapter pockets the spark making for poor running.
There is no deep reach plug that will extend the plug thru an adapter.
Take apart a new champion & weld in a pipe nipple @ the base & reassemble. Use the same champions for the other 3 cylinders.
Another project to my list.

The explosion whistle should do no engine harm at light to moderate throttle at light engine loading, Running the spark a little late might modulate the sound and further reduce engine stress. I would not operate the whistle on a steep upgrade for more than a second or two.
The wolf whistle can be modulated using the throttle and the pull wire. A slightly richer than normal mixture might be a good idea if using the whistle a lot.

George House wrote: ↑

Fri Jul 25, 2025 6:46 am

I call the explosion whistle in the picture that Dan posted - a crankshaft breaker. Back in ‘76 during the Colorado centennial tour I was a 26 year old kid with an explosion whistle on a T. I loved its ‘chortle’ sound when actuated going down an incline road. When ascending a Rocky Mountain road the actuated singular loud whistle could be heard for miles. This was when my crankshaft broke. My forensic determination was that cylinder explosive power was stolen from the T’s forward momentum and assigned to this damn “hey look at me” device causing engine carnage. I threw the explosion whistle away.

George,

My take on this, is that your crank was about to break anyway if something that was essentially a misfire, caused by using an explosion whistle, was the last straw. I can see, however, that under a heavy load, the whistle did your engine no "favors". Probably a good idea to not use it under those circumstances.

WillyR wrote: ↑

Thu Jul 24, 2025 11:06 pm

I think I’ll hold out for a splitdorf plug or two, depending on the going rate…


I will also ask for the adapter and long reach plug if anyone has spares of either.

Willy,

If you're thinking of the Splitdorf plug with the whistle adapter, and you actually can find one, you're likely to end up with a used-up or "not so great" plug. These types of things work better as shelf decorations for spark plug collectors. In other words, it most likely will not be cheap and will also likely not work well.

As to the long reach plugs, for use in the more traditional style of explosion whistle, just be sure that the whistle adapter has room within it to accept the extra length.

speedytinc wrote: ↑

Mon Jul 28, 2025 11:50 am

"With a welder, drill and some tubing I imagine one wouldn’t be too hard to make out of a Champion X" Credit to Tadpole.
There is the solution.
Spark plugs with the outlet built in are quite rare & big $$. A matching set with one with the outlet built in, like the splitdorfs are mega $$$
Using the adapter pockets the spark making for poor running.
There is no deep reach plug that will extend the plug thru an adapter.
Take apart a new champion & weld in a pipe nipple @ the base & reassemble. Use the same champions for the other 3 cylinders.
Another project to my list.

I'd love to see a schematic, or have an example in my hot little hands to make my own, it wouldn't be above my abilities.

TXGOAT2 wrote: ↑

Mon Jul 28, 2025 12:00 pm

The explosion whistle should do no engine harm at light to moderate throttle at light engine loading, Running the spark a little late might modulate the sound and further reduce engine stress. I would not operate the whistle on a steep upgrade for more than a second or two.
The wolf whistle can be modulated using the throttle and the pull wire. A slightly richer than normal mixture might be a good idea if using the whistle a lot.

Jerry VanOoteghem wrote: ↑

Mon Jul 28, 2025 12:15 pm

WillyR wrote: ↑

Thu Jul 24, 2025 11:06 pm

I think I’ll hold out for a splitdorf plug or two, depending on the going rate…


I will also ask for the adapter and long reach plug if anyone has spares of either.

Willy,

If you're thinking of the Splitdorf plug with the whistle adapter, and you actually can find one, you're likely to end up with a used-up or "not so great" plug. These types of things work better as shelf decorations for spark plug collectors. In other words, it most likely will not be cheap and will also likely not work well.

As to the long reach plugs, for use in the more traditional style of explosion whistle, just be sure that the whistle adapter has room within it to accept the extra length.

I don't see using the whistle while climbing a hill or under a critical load.

Yeah, the existing modified plugs may very well be "used up" and that would explain why there are more whistles than modified plugs available on the ebays....

looking at online pictures of the adapter that is currently available....

I'm betting I could get it machined to sit deeper, and/or modify it to fit a long reach plug better/deeper into the chamber for more efficient combustion.... at least as good as stock combustion, or close enough that it won't matter.......

In making an adapter, I'd want to get the spark gap as close as possible to the stock position and keep the inside volume of the adapter on the cylinder side of the valve as small as possible.

Jerry, that’s so ludicrous that you could assume a ‘misfire’ couldn’t cause a T crankshaft to break if it wasn’t previously weakened. You’d have no idea what condition my recently rebuilt engine was in back in 1976. Granted, I foolishly allowed 15-20 consecutive loud explosion whistles to fire off when the crankshaft broke. Learned my youthful lesson..

George House wrote: ↑

Tue Jul 29, 2025 1:58 pm

Jerry, that’s so ludicrous that you could assume a ‘misfire’ couldn’t cause a T crankshaft to break if it wasn’t previously weakened. You’d have no idea what condition my recently rebuilt engine was in back in 1976. Granted, I foolishly allowed 15-20 consecutive loud explosion whistles to fire off when the crankshaft broke. Learned my youthful lesson..

Okay, so I'm ludicrous, so be it... Not sure why you need to be so defensive. Can I not have my own opinion, "ludicrous" as it may be?


BTW, do you think that every misfiring Model T will break a crankshaft?

If it's misfiring, it's still running....

I spoke with a gentleman at an online vendor and he had a suggestion for a plug to use with the adapter.....

If the experiment fails I'm out $15....

this is fun... learning more than I ever wanted to know about spark plugs.....

I'll order the adapter later today.

no luck finding a source for long reach 1/2" spark plugs.

-BUT- there are a plethora of long reach 14 mm plugs. 3/4" and 1"

once I get the adapter (and 14mm adapter) I'll see if a 14mm plug will reach far enough -AND- perform as well as a stock set of plugs...

-OR- a stock plug in the adapter... etc...

if none perform well for everyday use, then whichever performs good enough for parades will get used a couple times a year for parades..

One word of warning. Be care full how you route the wire you pull to operate the whistle. Spark plug wires bite!! Les

Lessumner wrote: ↑

Wed Jul 30, 2025 4:44 pm

One word of warning. Be care full how you route the wire you pull to operate the whistle. Spark plug wires bite!! Les

I'm proud of how I have my wolf whistle routed, maybe I'll post up how I did it.

I don't think I'll have a problem routing it around the plug wires, the T is one of the most neatly organized engine bays ever...

maybe I'll keep that on the passenger side just in case....