Author Topic: .020 mag. piston  (Read 2961 times)

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Offline racer21

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.020 mag. piston
« on: September 16, 2012, 02:28:20 pm »
hey guys,
i have broke 2 pistons in 8 races.the piston number is 797010 this is a
magenium piston and both of them broke where the lock is at for the wrist
pin.is there any way to have them welded back up or do i need to buy another
one? i have run stock parts with a small cam for 4 yrs and never broke anything.
this year i buy all aftermarket and started broking pistons.
i have an arc rod,aftermarket piston,pc 246 cam and a stock flywheel.i have only
turned this motor at 6000 rpms.

thanks
harold

Offline Jeff McKelroy

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Re: .020 mag. piston
« Reply #1 on: September 16, 2012, 05:37:17 pm »
Hmm, that is a concern.  You said aftermarket, and by that you mean other than a B&S piston.  Is the lock pin area differently designed than a briggs, meaning a steel wrist pin with 2 locks?  Are you using new locks, or reusing old locks?  Reason is steel and Mg don't like eachother too much.  Can you post a pic of the failed piston, and all other components that have failed?  You can't weld Mg. It will catch fire.

Offline racer21

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Re: .020 mag. piston
« Reply #2 on: September 16, 2012, 05:50:40 pm »
sorry it is a briggs piston.i did use the new clips for the wrist pin and it
only needs 1.it cracks on the side that the clip goes on.

Offline trbinrat

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Re: .020 mag. piston
« Reply #3 on: September 16, 2012, 08:02:05 pm »
  You can't weld Mg. It will catch fire.

You can weld magnesium. I've done it a few times with limited success. 

Repairing a mag piston. I doubt that would work
Mark
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Offline BIG AL 202

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Re: .020 mag. piston
« Reply #4 on: September 17, 2012, 12:54:22 pm »
Be real careful welding mag, when heated it will produce it's own oxygen and will burn itself up. Talk to a welder that has done it before you try!
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!

Offline Jeff McKelroy

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Re: .020 mag. piston
« Reply #5 on: September 17, 2012, 02:28:06 pm »
You can weld magnesium. I've done it a few times with limited success. 


Huh!  I didn't know that, I thought the high welding temp would ignite the metal!  Learn something new on Heymow every day.
I just wonder if the coating is missing off of the clip, which would eat into the metal and weaken the pin boss?

I run into it all the time with people putting steel drain plugs in their NP246 transfer cases, instead of the coated Al ones.  It somehow destroys the Mg case on a molecular level...

Offline BIG AL 202

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Re: .020 mag. piston
« Reply #6 on: September 17, 2012, 03:36:34 pm »
MAYBE, ALSO IF YOU SCRATCH THE PISTON IT PUTS IN A FAULT LINE TO CRACK OR BREAK.
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!