Author Topic: Petteroid piston to cylinder clearance  (Read 4116 times)

mkdutchman

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Petteroid piston to cylinder clearance
« on: October 18, 2007, 07:16:39 PM »
Does anyone know what the piston to cylinder clearance is supposed to be on an Ashmawegh 3.5 Petteroid? That is between the piston and the cylinder wall.

mobile_bob

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Re: Petteroid piston to cylinder clearance
« Reply #1 on: October 19, 2007, 12:43:03 AM »
i don't know for sure, but i would expect it to follow a good rule of thumb of about
.001" per inch of diameter.
so for a 3" piston, .003"

maybe a bit more if the engine is going to be run under heavy loading, or
if it is running cool and then asked to take a max loading before the engine is up to normalized temps
in which case maybe an extra thou or two, but this would be for an unusual application in my opinion.

why do you ask? are you looking for a max limit? such as after a rehone of the cylinder?

also the piston (if made properly) will not be round but more like an oval in shape, wider perpendicular to the
wristpin (grudeon pin for our english purest's), so be sure to measure for clearance in the center of the skirt
90 degrees from the pin.
(just in case you didn't already know, if you already knew that,, then nevermind)  :)



bob g
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rmchambers

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Re: Petteroid piston to cylinder clearance
« Reply #2 on: October 19, 2007, 01:04:29 AM »
Gudgeon Bob, like the fish  :D

mobile_bob

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Re: Petteroid piston to cylinder clearance
« Reply #3 on: October 19, 2007, 01:45:04 AM »
ah hell,, grudgeon, gudgeon, pidgeon,, :)

you say potatoe .. i say pototo,,, lol

:)

bob g
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Tom

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Re: Petteroid piston to cylinder clearance
« Reply #4 on: October 19, 2007, 02:44:48 AM »
Do all the petteriods come with aluminum pistons? Because the .001 per inch of piston may be to much for a castiron piston.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

Doug

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Re: Petteroid piston to cylinder clearance
« Reply #5 on: October 19, 2007, 03:08:44 AM »
I don't know, a machine rated to 1800 rpm with a cast piston might be a problem.

For the 102mm its 1.25 - 1.5 mm, but this is a considerably bigger engine
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listerdiesel

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Re: Petteroid piston to cylinder clearance
« Reply #6 on: October 19, 2007, 07:54:52 AM »
I don't know, a machine rated to 1800 rpm with a cast piston might be a problem.

For the 102mm its 1.25 - 1.5 mm, but this is a considerably bigger engine

Sounds like a typo, Doug.

0.125mm - 0.15mm sounds better?

Peter


rcavictim

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Re: Petteroid piston to cylinder clearance
« Reply #7 on: October 19, 2007, 08:12:07 AM »
Beware.  You start introducing engine internal dimensions in metric and you can expect a train wreck.  All my feeler gauges are in thousandth`s of an inch and I like it fine that way thank you. Millimeters were for making cigarettes longer when I was growing up.   :D
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mkdutchman

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Re: Petteroid piston to cylinder clearance
« Reply #8 on: October 19, 2007, 12:31:26 PM »
why do you ask? are you looking for a max limit? such as after a rehone of the cylinder?

Because I got a new cylinder from Atul, and I was surprised at how loose the piston is inside the cylinder. Then I checked it in the old rusty carboned cylinder and it was quite loose there too

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Re: Petteroid piston to cylinder clearance
« Reply #9 on: October 19, 2007, 09:24:54 PM »
OH I'm way off I thought we were talking bump clearence.

All I can find is .010 max wear for the liner
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