Wrist pin bent

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1972ho
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Wrist pin bent

Post by 1972ho »

Will a wrist pin that .0002- .0003 out of shape cause any worry if the rest of the 7 or in good shape or should I buy a new set,This is a H11 tool steel pin.
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Re: Wrist pin bent

Post by mag2555 »

If your piston to Bore clearance is .007" or more maybe not, but I don't know if I would take a chance on beating up a cylinder wall for the price of a new pin, I am not the gambling type !
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Re: Wrist pin bent

Post by Mark O'Neal »

Why is it bent?
1972ho
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Re: Wrist pin bent

Post by 1972ho »

Piston hit the head when a rod broke bolt broke.
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Re: Wrist pin bent

Post by Newold1 »

If I had a piston and rod combo and the rod bolt broke and slammed the piston into the head to bend the pin , I would be replacing the rod, and the piston with a new pin. JMO
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Re: Wrist pin bent

Post by user-23911 »

Why did the rod bolt break?

Are you sure that the piston didn't get stuck in the bore first and the crank pulled the bottom out of it?


"Piston hit the head when a rod broke bolt broke."
Makes no sense to me.
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Re: Wrist pin bent

Post by modok »

Pistons hit heads when the rod bearings fry and clearance becomes huge.

Due to impact loads from huge clearance, bolt breaks.

These are two separate events, but the more power you make the closer together these events become.

Also, detonation can bend pins, and mess up rod bearings.
Which came first, chicken or egg? Anyway, pin bent .0005? sure run it :P i think it'll work.
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Post by dwilliams »

You're sure the pin is bent, as opposed to your measuring method picking up wear from the rod bushing or pin bosses?

I've never specifically checked a pin to see if it was bent. As long as it slips through the piston without binding, I've always considered it good to go.

The handful of times a pin wouldn't go through the piston, neither would any other pin. A few passes across the rod hone usually showed contact patches showing the two sides of the piston bore were not longer parallel and concentric, if not simply undersize.
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Re: Wrist pin bent

Post by Mark O'Neal »

What do the pin holes look like?
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Post by Mark O'Neal »

dwilliams wrote: Sat Jun 16, 2018 1:18 am I've never specifically checked a pin to see if it was bent. As long as it slips through the piston without binding, I've always considered it good to go.
What if the pin holes aren't straight......as none of them were, back in the day.... :lol:
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Post by Mark O'Neal »

dwilliams wrote: Sat Jun 16, 2018 1:18 am I've never specifically checked a pin to see if it was bent. As long as it slips through the piston without binding, I've always considered it good to go.
What if the pin holes aren't straight......as none of them were, back in the day.... :lol:
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Re: Wrist pin bent

Post by Mark O'Neal »

'twas so funny, I had to post it twice....
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Re: Wrist pin bent

Post by mag2555 »

Lol, of course with I beam type steel rod and the right vise set up to span around the piston and support the pin you could bend that 0005" into the rod and have things play well!
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Re: Wrist pin bent

Post by 1972ho »

I just called trend and bought a new one.
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Re: Wrist pin bent

Post by stealth »

1972ho wrote: Fri Jun 15, 2018 10:59 am Will a wrist pin that .0002- .0003 out of shape cause any worry if the rest of the 7 or in good shape or should I buy a new set,This is a H11 tool steel pin.
Can’t hurt to replace...

Seriously though how much does the pin flex in dynamic condition...at 6-7000 rpm? Bet it’s well over .0003...
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