Spark Plug Numbers

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February 13th, 2017, 11:20 AM
Don Cavey

Spark Plug Numbers

We have hashed this out before but I have seen recent questions about it. So, here is the information again for the benefit of our newer M715 owners.

I believe that the spark plugs that I originally used in my truck are Autolite 2344. These cause problems with the spark plug wires because the plug is longer than original and the wire nuts just about hit each other and are difficult to install and remove. One of our members suggested 2407 which is shorter. I have them but have not tried to install them because the truck runs so good and "If It Ain't Broke, Don't Fix It".

FYI, Autolite information, the longer plug:

http://www.autolite.com/Productfinde...il?partNo=2344

This plug is non-resistor and a little colder.

The shorter plug:

http://www.autolite.com/Productfinde...il?partNo=2407

This plug is resistor and hotter.

I know this has been hashed out before. Here is the thread started and researched by "Beast":

http://www.m715zone.com/vb/showthrea...t=26295&page=2
February 13th, 2017, 11:23 AM
Don Cavey

I got mine from NAPA and whilst they didn't have them in stock, they ordered them. I see that O'Reilly has them listed but not in stock for $7.49, which is a very good price. The local O'Reilly here has been very good at looking up and ordering things for me.

http://www.oreillyauto.com/site/c/de...2497&ppt=C2389
February 14th, 2017, 07:34 PM
Nailhead

I installed a set of AC-Delco 41-803 plugs last week, gapped to .030. Working great, so far.
February 15th, 2017, 10:04 AM
Don Cavey

Quote:

Originally Posted by Nailhead

I installed a set of AC-Delco 41-803 plugs last week, gapped to .030. Working great, so far.

Do you have a stock engine? The O'Reilly website shows them as being tapered seat and non-military. Just wondering...
February 15th, 2017, 10:15 AM
Nailhead

Quote:

Originally Posted by Don Cavey

Do you have a stock engine? The O'Reilly website shows them as being tapered seat and non-military. Just wondering...

As far as I know. It does have tapered seats in it, though, which the Champion RF12-YC plugs I replaced didn't fit.

I just wanted sparkplugs that would work in my engine, I wasn't looking for the military ones. I should have specified they were civvy plugs.
February 15th, 2017, 12:01 PM
Don Cavey

If you have the military Kaiser Jeep overhead cam 230 CID engine, the head is not made for tapered seats. It has a flat surface where the plug bottoms out and is designed to have a crush washer between the head and the spark plug. You might have a problem with heat transfer between the plug and the head with heat not being transfered to the head from the plug.

Just my 2¢ though...
February 16th, 2017, 10:00 AM
Nailhead

Quote:

Originally Posted by Don Cavey

If you have the military Kaiser Jeep overhead cam 230 CID engine, the head is not made for tapered seats. It has a flat surface where the plug bottoms out and is designed to have a crush washer between the head and the spark plug. You might have a problem with heat transfer between the plug and the head with heat not being transfered to the head from the plug.

Just my 2¢ though...

When I opened the first spark plug box, I was annoyed to see a tapered-seat plug. I checked the spark plug hole, and saw a tapered seat. I checked it again with a BRIGHT flashlight & reading glasses. I'm going to check it again today, but I know a tapered spark plug seat when I see one and I swear that's what my engine has.
February 16th, 2017, 06:43 PM
Nailhead

Indeed, sure as the sun rises and beer satisfies, this cylinder head has tapered spark plug seats.
February 16th, 2017, 06:46 PM
Nailhead

I tried to get a decent pic, but the phone wouldn't focus, and I've given up uploading from an actual camera.
February 16th, 2017, 08:11 PM
Nailhead

Actually, it almost looks like it has a combination of seat types, like you could use either type of plug.
February 14th, 2018, 03:23 PM
ColoradoSpringsRob

Final Word: 2407?

My brush truck livery 67 M715 was just delivered Saturday, and ohhhhh I am in love. Man, what a beautiful expression of utility. Love it.

Anyway, she is at the muffler shop now, and I have a carb kit coming to me via ebay, but regarding plugs, is the 2407 the final word on plugs? I have read several threads, and given heat range and length, and price too, sounds like this is the plug to buy?

Can someone weigh in on this, who has run these plugs, and confirm they are the way to go?

Thanks fellas. RB
February 14th, 2018, 04:05 PM
Beast

Quote:

Originally Posted by ColoradoSpringsRob

My brush truck livery 67 M715 was just delivered Saturday, and ohhhhh I am in love. Man, what a beautiful expression of utility. Love it.

Anyway, she is at the muffler shop now, and I have a carb kit coming to me via ebay, but regarding plugs, is the 2407 the final word on plugs? I have read several threads, and given heat range and length, and price too, sounds like this is the plug to buy?

Can someone weigh in on this, who has run these plugs, and confirm they are the way to go?

Thanks fellas. RB

Yes. the 2407 is the proper plug to run. I run them in both my trucks and the shorter plug makes installing the waterproof cap much easier than with the taller 2344's
July 21st, 2018, 02:45 PM
Ec4fish

I am running civi lines from a distributor. The plugs that came in mine were an Ac 303. I had them switched over to the 41-803. Man what a difference. It immediately went from 20 mph to 50mph. Might even go higher, I just keep running out of road to see. Hole is tapered. ( the ac 303, were definitely not what should have been in there. 1/4 to short, and non tapered head.)
July 21st, 2018, 08:15 PM
Don Cavey

Quote:

Originally Posted by Ec4fish

I am running civi lines from a distributor....Hole is tapered. ...

If you are saying that the plug that you are using is for a tapered hole in the head, that is not correct. The Jeep 230 CID engine head is for a plug with a gasket.

Sorry if I misunderstood what you were saying.
July 22nd, 2018, 07:51 AM
Ec4fish

Don, I wouldn’t know a tapered hole from a hole in the ground. I have a mechanic helping me. When the plugs were pulled, he told me I had the wrong new plugs, because they were tapered and too long. I asked him to inspect the holes to see if they were tapered (because of this thread we are posting on.) He found two things: that the holes were tapered, according to him. That the plugs installed by the last person working on this, used a plug to short in the threaded area, by at least a quarter inch. This pulled plug was also not tapered.
After using a thread chaser, to clean the carbon, the new plugs were gapped to .030, and installed. It ran like a champ. Before the new plugs, top speed was 35, at best, and slow on the pick-up. With the newer plugs, 50 mph, and much better acceleration.
I would like to get Nailhead to weigh in on how his is running. If the plugs are too hot for this vehicle, and I should find something else. I used his plug numbers, because I had civi leads off the distributor. I was not looking to replace the distributor, also.
July 22nd, 2018, 08:57 AM
Don Cavey

2 Attachment(s)

This is what we mean when we say, "Tapered Plug". Note the pencil is pointing to the seat and it is tapered meaning that it uses no gasket, rather the taper to seal the plug to the head.

And the next Champion plug is a representative of what our original military plugs looked like albeit silver instead of the normal black. Notice that it has a flat seat and uses a metal gasket.
July 22nd, 2018, 09:02 AM
Ec4fish

Gotcha, thanks for the lesson. The new ones did have a crush washer. Not sure if there was a taper behind it, but I guess it doesn’t matter. They work, now I just have to worry about the heat you mentioned.
July 22nd, 2018, 10:56 AM
Nailhead

That spark plug bore really is deceptive in its appearance, looking like it has a tapered seat in it. You could get away with running tapered-seat plugs in a crunch, but they come loose pretty quickly.

After Mr. Cavey's patient admonitions, I switched to flat-seat plugs and they work great, obviously.
July 22nd, 2018, 01:41 PM
Don Cavey

Quote:

Originally Posted by Nailhead

That spark plug bore really is deceptive in its appearance, looking like it has a tapered seat in it. You could get away with running tapered-seat plugs in a crunch, but they come loose pretty quickly.

After Mr. Cavey's patient admonitions, I switched to flat-seat plugs and they work great, obviously.

Admonitions! I hope not, if so, I'm Sorry. :D

BTW, a plug with a washer will never have a taper seat. It is one of the other. Our trucks like the crush washer, which are technically made for one time use. But... many of us (yes, me too...) have been known to use them more than once.
July 26th, 2018, 09:38 AM
Nailhead

Quote:

Originally Posted by Don Cavey

Admonitions! I hope not, if so, I'm Sorry. :D

BTW, a plug with a washer will never have a taper seat. It is one of the other. Our trucks like the crush washer, which are technically made for one time use. But... many of us (yes, me too...) have been known to use them more than once.

Absolutely no apologies necessary, Don-- I thank you for your guidance!

The seat I was describing was in the head, not on the plug: the plug hole is chamfered, and that's what threw me initially.
September 19th, 2018, 08:25 AM
Mopic

How about the AER72S plug?
September 19th, 2018, 08:27 AM
Mopic

Is the 2407 plug the same as AER72S plug?
September 24th, 2018, 10:35 AM
Mopic

AER72S spark plug

I found this on a different discussion board. Can ANYONE tell me if its accurate?

Warning, The Ols Champion Number AER-72S was the spark plug for the M-715 OH Cam Tornado Engine, only. It is 1/2 " Reach, the 2245 is 3/8" Reach and is the latest Autolite version for the M-151.
September 24th, 2018, 02:38 PM
Don Cavey

Quote:

Originally Posted by Mopic

How about the AER72S plug?

I am not familiar with that plug so I can't comment. I have only seen the Autolite. Hopefully another member has the info.