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Old 05-21-2008, 01:11 AM   #1
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Default Do engines need pinch?

Hi Guys,

I do know the top of the sleeve is tapered. But do we need pinch at all? All we want is compression right? Please correct me if I'm wrong. Thanks!
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Old 05-21-2008, 02:34 AM   #2
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Yes they need a pinch to help compression.
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Old 05-21-2008, 02:36 AM   #3
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i managed to lose all the pinch on the engine in my firestorm (first engine, lots of tuning problems) but it still has compression. and still runs ok!
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Old 05-21-2008, 03:38 AM   #4
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The upper area of sleeve is hotter than mid and bottom area, they expand more, that's why they are tappered.
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Old 05-21-2008, 03:59 AM   #5
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As long as you have compression with the glow plug in you should be ok. Does not really matter if the glow plug is out and you do not feel compression.
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Old 05-21-2008, 04:09 AM   #6
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Pinch is different that compression, on fully broken in motor with the glow plug out there should be no resistance to the piston moving in the sleeve. But when you put the glow plug back in it should be hard to turn the motor over warm or cold. That is compression, when a motor is easy to turn over warm then it is worn out, as a general rule. Along with that when the motor does get up to temp it has trouble idling and running well in general
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Old 05-21-2008, 12:29 PM   #7
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as long as it idles good and holds a tune you are good to go..
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Old 05-21-2008, 06:17 PM   #8
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Quote:
Originally Posted by schmidt452 View Post
Pinch is different that compression, on fully broken in motor with the glow plug out there should be no resistance to the piston moving in the sleeve. But when you put the glow plug back in it should be hard to turn the motor over warm or cold. That is compression, when a motor is easy to turn over warm then it is worn out, as a general rule. Along with that when the motor does get up to temp it has trouble idling and running well in general
That clears things up! Thanks!

Quote:
Originally Posted by joe of loath View Post
i managed to lose all the pinch on the engine in my firestorm (first engine, lots of tuning problems) but it still has compression. and still runs ok!
Yeah, we're in the same boat (nope I don't run a Firestorm, just similiar situation).
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Old 05-21-2008, 08:24 PM   #9
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Is this part of a why a turbo plug is so good? I have a JP.21and it got nothing with no plug in it. But with the plug it has some pop left in it and it runs fine.
With the best fuel mileage of any of my motors.
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