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Piston tool - how loose without a micrometer?

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Re: Piston tool - how loose without a micrometer?

Post  1/2A Nut on Tue Oct 06, 2015 8:03 pm

Mark has the right idea.

I do pitty pitty tap tap once I am close rotating the tool around the ball socket for a even all around flush fit if too tight no worries it loosen up quick to a snug fit. If done right you can get many flights without the need to adjust. Once the gap has been induced through use the socket tends to open up fairly fast based on prop size and load.
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Re: Piston tool - how loose without a micrometer?

Post  balogh on Wed Oct 07, 2015 4:50 am

My experience is that if you readjust the balljoint gap once or twice after the few initial hours of run i.e. aftre the natural the heat treatment of the piston, it will not loosen up anymore, the metal hardens.

A really tiny gap is desirable, though, to allow the build-up of the castor varnish in the cup and on the ball end of the rod that will efficiently keep metallic surfaces from touching and abrasing each other.

I killed one or two pistons already with zero gap but still free ball movement. The crown of the piston is punctured by the ball if no varnish is allowed to build.
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Re: Piston tool - how loose without a micrometer?

Post  Cribbs74 on Wed Oct 07, 2015 12:09 pm

I have reset dozens of pistons, have yet to screw one up. Not sure what is happening out there, perhaps some poor reset tools were sold at one time.

I don't tap, I whack, firm and straight down. I use a small hammer, maybe 1-2oz. I keep the anvil and reset rod super tight against the piston and ball socket I also work on a concrete floor.  1-2 firm hits and the slop is gone. If I over do it then I do what Mark suggested and add a drop of oil and work the rod. Then I run it and after the run it's usually perfect.

That's my method and it hasn't failed me yet. Yet... Shocked
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Re: Piston tool - how loose without a micrometer?

Post  getback on Wed Oct 07, 2015 12:33 pm

I also have done quite a few and have had no problems with them blowing the top of the piston out. I use like Ron said 1-2 oz. small hammer I put mine on an flat anvil at the vice and hold it down firm so as not to bounce, and rotate "Sharpe but light blows ,, Are you cleaning the socket out before you start , I do with carb. cleaner and dry with compressed air ? Eric Huh...
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Re: Piston tool - how loose without a micrometer?

Post  balogh on Wed Oct 07, 2015 1:29 pm

I do small taps on concrete surface with the resetting tool pressed down hard and constantly turning between taps, and rather fiddle around 10-15 minutes with the resetting than doing a "quick and dirty" job. Sudden blows may make the piston top a mushroom that practically renders the piston a scrap. Seen that, done that, mourned that.
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Re: Piston tool - how loose without a micrometer?

Post  Cribbs74 on Wed Oct 07, 2015 2:42 pm

Balogh,

I wasn't alluding to a two handed over the head swing, just sharp, firm and straight down hit.

If the piston is mushrooming then either the holding fixture is not flat or the piston is being lifted when tapping. That's the only way I can see it mushrooming.

I will say this, there are many ways to do something and have the same outcome. If your way works for you then keep doing it. I was only posting what works for me.

Ron

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Re: Piston tool - how loose without a micrometer?

Post  balogh on Thu Oct 08, 2015 3:25 am

No problem Ron, I also did not think you were steamhammering on the pistons. My positive outcomes always followed a slow, cautious tapping process, after I had killed 1 or 2 pistons by mushrooming.
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Re: Piston tool - how loose without a micrometer?

Post  OVERLORD on Thu Oct 08, 2015 4:13 am

Cribbs74 wrote:I have reset dozens of pistons, have yet to screw one up. Not sure what is happening out there, perhaps some poor reset tools were sold at one time.

I don't tap, I whack, firm and straight down. I use a small hammer, maybe 1-2oz. I keep the anvil and reset rod super tight against the piston and ball socket I also work on a concrete floor.  1-2 firm hits and the slop is gone. If I over do it then I do what Mark suggested and add a drop of oil and work the rod. Then I run it and after the run it's usually perfect.

That's my method and it hasn't failed me yet. Yet... Shocked

Ron, the concrete floor you mentioned is very important. With a solid underground, every tap with a hammer has its results. I tried a table and benches inside our house. It only makes a noise and everything bounces up and down without any change in the ball joint. I now use our granite front door step as a base. That works!!
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