7/8-18 spark plugs

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amtrac

Member

• Feb 5, 2019

• #1

Reading a topic below about the B that is missing on one cylinder and someone suggested using a hotter spark plug. What would be a "hotter" plug than AL 3076 that I am now using for my 37 B? I heard that AL is no longer making 3077s. My plugs DO foul with carbon because it is just a show/parade tractor and doesn't have to work hard. Anybody using Champions in unstyled B's?

 

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Hayfarmer

Well-known Member

• Feb 5, 2019

• #1

When I worked for JD dealer we recommended Champion D23 in A and B tractors. They have a longer base and don't seem to foul as much. There are autolite plugs that are supposed to be the same but don't have the long base.

 

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Mike M

Well-known Member

• Feb 5, 2019

• #1

The D23 are 18mm thread so they will not fit.

 

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Mike M

Well-known Member

• Feb 5, 2019

• #1

Lean your carb. down since it is carbon fouling. Also put a curtain on the front to close off the radiator and let it get warm.

 

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amtrac

Member

• Feb 5, 2019

• #1

Yessir you are correct. They have to be 7/8-18 thread.

 

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amtrac

Member

• Feb 5, 2019

• #1

Leaned her out until she started to miss. Temp gauge says medium most of the time. Do I want to run the engine till the gauge says H?

 

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Mike M

Well-known Member

• Feb 5, 2019

• #1

Many times plugs when fouled do not seem to respond to cleaning very well. Also gear it down and run it more RPM may improve it if just idling around. May also have a weak spark issue too ?
I used to think if fouling bad maybe the engine needs overhauled. But after the 1 unstyled B I had started and ran so good even when it was blowing droplets of oil out the stack that does not seem to always cause issues ? found out later from the guy I sold it to the wrist pin scored up the cylinder.

 

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buickanddeere

Well-known Member

• Feb 5, 2019

• #1

Get the coolant temp up to 195F or higher . Fouling with go away . Engine will run smooth when leaner and cleaner with the manifold , ports and combustion chambers hot . Gasoline will vapourize instead of staying in a liquid form .

 

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John T

Well-known Member

• Feb 5, 2019

• #1

In light duty or oil burners I prefer the hotter deep reach side wire electrode Autolite 3077. I see them for sale at about any antique tractor show I attend. That's the 7/8 plugs of course.

It helps if you get and keep the temp up to 180 and over and lean the carb as much as possible for light duty parade use

John T

 

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ET

Well-known Member

• Feb 7, 2019

• #1

Autolite has changed their number system. Try an autolite 386.

 

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John T

Well-known Member

• Feb 7, 2019

• #1

ET, correct me if I'm wrong but aren't the 386 388 and 3116 (non resistor) all 18 mm plugs while 3076 and the hotter deep reach side wire electrode 3077 7/8 plugs???????? At antique tractor shows I see all kinds of 3076 and 3077 for sale.

Good talkin to ya

John T

 

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buickanddeere

Well-known Member

• Feb 7, 2019

• #1

The reach is too short on a 388 or 3116 as it is . Worse in an engine intended for the 3076/3077.
I have started chucking new 3116 plugs in the lathe and cutting the shoulder back until it’s just 1/8” wide. This allows the plug to thread in deeper and unshroud the electrodes .

 

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ET

Well-known Member

• Feb 7, 2019

• #1

I just tried to get 3116 for my 50 and they said 386 was the replacement from their supplier. I have used the 3076 with good results also.

 

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buickanddeere

Well-known Member

• Feb 7, 2019

• #1

(quoted from post at 13:18:25 02/07/19) I just tried to get 3116 for my 50 and they said 386 was the replacement from their supplier. I have used the 3076 with good results also.

Click to expand...

Supplier was just taking the easy way out with less shelf stock . The catalogue does cross reference the 3116 to the 368/388 . They look about the same however the 3116 is non resistor.

 

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nlastovi

Member

• Feb 7, 2019

• #1

(quoted from post at 09:19:46 02/07/19)
I have started chucking new 3116 plugs in the lathe and cutting the shoulder back until it’s just 1/8” wide. This allows the plug to thread in deeper and unshroud the electrodes .

Click to expand...

that's a real clever idea. I like it!

 

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buickanddeere

Well-known Member

• Feb 7, 2019

• #1

(quoted from post at 14:40:02 02/05/19) Leaned her out until she started to miss. Temp gauge says medium most of the time. Do I want to run the engine till the gauge says H?

Click to expand...

200-205F is good

 

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John T

Well-known Member

• Feb 8, 2019

• #1

Yep the 386 is around the same heat range as 3116 but 3116 is a NON Resistor which I highly recommend if a Mag ignition is used. However they are 188 MM instead of the 7/8 like many older unstyled tractors use.

John T

 

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John T

Well-known Member

• Feb 8, 2019

• #1

Your question: What would be a "hotter" plug than AL 3076 that I am now using for my 37 B?

3076 is a 7/8 plug so you cant use 386 or 388 or 3116 (Non Resistor) which are 18mm. A hotter then 3076 Autolite (a 7/8 plug) is the deep reach side wire electrode 3077 which I see for sale at most antique tractor shows, that's my recommendation along with get the temp up higher and run the carb on the lean side if possible.

John T

 

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amtrac

Member

• Feb 8, 2019

• #1

General consensus to my question is to find hotter plugs and run the engine up to "high" temp. Tractor shows are few and far away from where I live, but I did locate some Champion 44 plugs with the long porcelain and the side wire. I will try them instead of the 3076 plugs that I have in there now. We'll see if it helps. Thanks for all the suggestions.