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short/long plugs

Old 06-23-2007, 01:02 PM
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Codeblack
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Default short/long plugs

hey hey,
what is the difference in long/short plugs in terms of looks? I have only one plug and no clue how to distinguish between the two. any dimensions are much appreciated. thanks folks.
Old 06-23-2007, 06:26 PM
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gubbs3
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Default RE: short/long plugs

Most plugs are considered "standard" or rather "long". The most common difference are O.S. plugs which are considered "short."

Look here: http://www.osengines.com/accys/glowplugs.html

Any of their non-turbo plugs would be the "short" variety. The LC-3 is their one offering which is the standard "long" plug.
Old 06-23-2007, 08:26 PM
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Default RE: short/long plugs

i see. thanks gubbs3, thats exactly what I was looking for. Ill carry on with breaking in my sts
Old 06-23-2007, 08:58 PM
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Default RE: short/long plugs

Plugs come in 3 lengths where there's what's usually called long and short but then there's the OS and Enya plugs which are a medium length. No one knows why both these Japanese plugs are different. The OS plugs don't even fit most of the OS engines properly! The photo shows the difference between them with an OS #8 plug in the middle.

There are no standards for plugs and even what's called a long or short can still vary slightly in length but only by a small amount. There are also differences in the thickness of the plug washers and that can be helpful in getting a plug to sit exactly flush with the surface of the combustion chamber which is the ideal.
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Old 06-23-2007, 09:22 PM
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Default RE: short/long plugs

Its easy to tell, short plugs usually has 1-2 less screw thread than long ones. Its best you get what kind of the plug the engine is made for.

Im guessing the extra short plug (above) is either for a tiny blocks for 1/16th cars or boats cause ive never seen them before
Old 06-23-2007, 09:54 PM
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Default RE: short/long plugs


ORIGINAL: Codeblack

i see. thanks gubbs3, thats exactly what I was looking for. Ill carry on with breaking in my sts
Is your D30M running away from you even after you have attacked all the air leaks and no tuning in the world will correct this? Does it overrev even while at idle and your slide calve is nearly closed inside the carb neck?

The D30M is designed and menat to use long plugs. If your engine runs away and you are trying to stop it by reducing the compression ratio (and thus the engine will cease running away), this is not a proper fix. It is only a band aid. This is the method I used to control my runaway D28M (the D28M and D30M share many of the same parts).

The problem in particular lies in the poor machining and production tolerances in manufacturing the carb (the D28M and D30M carb are the same). If you are experienceing a runaway engine such that you have to resort to useing a short plug, call STS and ask them to send you a properly machined and toleranced carb. Tell them the carb you have is faulty and is causing your engine to run away. They should be able to replace it for you since it is a production fault.
Old 06-24-2007, 01:43 AM
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Default RE: short/long plugs

thanks guys.
Jim, I havent really started officially breaking in my engine. I was looking for the differences between short/long plugs so I know what to purchase for this break in, thanks ill keep in mind what you said for the near future. And speaking of sealing sts, I was not able to get it completely dismantled. I tried to get the conrod off the crank while the sleeve was out but wasnt able to... I think thats because the engine is brand new and needs a little of wear and tear before completely taking it apart it. Have you had this problem with your new sts?
Old 06-24-2007, 02:15 AM
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Default RE: short/long plugs

Umm its fairly easy, i think you might just be doing it the wrong way. It usually comes out on TDC, with abit of budging on the piston

Why do u need to take out the crank to seal it anyway?
Old 06-24-2007, 10:02 AM
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Default RE: short/long plugs

The D30M is a beeyotch to get the conrod off, even at TDC.

To pull of the conrod from the D28M or D30M, you need to put the engine on a vise (use one with rubber pads and do not overtighten the vise), get a large zip tie and slip it around the conrod, and with pliers, pull the zip-tie firmly (apply a fair amount of stready force), and rock the crank left and right. So you can rock the crank left and right, leave the flywheel on so you can turn it with your other hand. You should hear a distinct "pop!" or "cling!" as the conrod comes off.

When purring the conrod back on, this can be as troublesome. I had to get a soft head mallet and a wooden dowel to tap the conrod back onto the crank pin.
Old 06-24-2007, 11:51 AM
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Default RE: short/long plugs


ORIGINAL: HeLLsGoD

Umm its fairly easy, i think you might just be doing it the wrong way. It usually comes out on TDC, with abit of budging on the piston

Why do u need to take out the crank to seal it anyway?
It is pretty tricky. I dont need to take everything apart in order to seal it, but I thought it was a good idea to completely inspect it before starting. Ill do what Jim said, and try to steadily force it out. thanks everyone. great help.

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