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how tight can I torque the spark plugs ?


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you dont need to torque the plugs. you should screw them in until they bottom out and give them a little bump and that should hold them.. if they are backing out you could possibly have some detonation. that can cause plugs to backout. look at the electrode and see if there is any damage to it.

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Trinity makes them and some other company that makes a head that uses domes that will spin around because there is no tab to hold them in place.

 

I'm guessing you have other problems. I had plugs back-out when I had some Bad domes before. Another cause would be detination. My dome was vibrating a little in the head causing the problem.

 

When I checked before I put in the domes it was flush with the lower plate on the Noss head. But it was only the mounting tab holding it in place (hight wise; the tab was keeping it flush because the notched area in the dome was about .001 taller than the base of the dome), the last rib on the dome was cut too low (lower that the notched area), so it didn't take long to make the notched area on the dome imprint into the head leaving up and down play. (but not enough to leak coolant aparently.)

Edited by Justintoxicated
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Please don't buy a plug lock...these guys are just having fun with you.

Your motor is telling you there is something wrong...figure out if it's not getting enough fuel, if it has an air leak or if it has too much timing advance....

 

The first time I install plugs I snug them, then turn it 1/2 to 3/4 turn after.

After that (the washer is crushed) 1/4 to 3/8 turn after snugged.

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Please don't buy a plug lock...these guys are just having fun with you.

Your motor is telling you there is something wrong...figure out if it's not getting enough fuel, if it has an air leak or if it has too much timing advance....

 

The first time I install plugs I snug them, then turn it 1/2 to 3/4 turn after.

After that (the washer is crushed) 1/4 to 3/8 turn after snugged.

:stupid: I concur, you should not need a plug lock, something is wrong.

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I agree with these guys. You probably have something causing the plug to back out. Your mods aren't listed but try mixing up some race gas and see if it still happens. The plugs backing out might be saving you from trashing the engine because of detonation.

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25cc is a fairly high compression dome for a Super Cub, more so a 10mm with advanced timing. That is going to vary, of course, with the porting and stuff. I've made quite a few SC domes and most of them are 25cc to 28cc. My guess is that your compression is 220 to 240 but I don't know how it's ported.

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25cc is a fairly high compression dome for a Super Cub, more so a 10mm with advanced timing. That is going to vary, of course, with the porting and stuff. I've made quite a few SC domes and most of them are 25cc to 28cc. My guess is that your compression is 220 to 240 but I don't know how it's ported.

 

 

WOW...that's interesting to know Dave.

4 mil of bore creates that much more compression...Wow...

 

Stinky....get in touch with Dave, founder and owner of NOSS machine Ind. and get some domes cut for less compression...

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