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Big gap between pistons?

  • Thread starter Thread starter Wicked_306
  • Start date Start date Sep 13, 2005
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Wicked_306

New Member
Aug 14, 2005
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Sep 13, 2005
#1
  • Sep 13, 2005
  • #1
What would cause a gap between the pistons and the piston wall. It is at the front of each piston. It looks like the pistons are not square in the cylnder. What would cause this? Thanks
 

Rick 91GT

Mustang Master
Nov 29, 1999
9,692
95
99
PA
Sep 13, 2005
#2
  • Sep 13, 2005
  • #2
Are you looking at an assembled shortblock?
 

wht93gtEd

Active Member
Nov 11, 2004
0
9
29
Jersey Shore, New Jersey
Sep 13, 2005
#3
  • Sep 13, 2005
  • #3
Wicked_306 said:
What would cause a gap between the pistons and the piston wall. It is at the front of each piston. It looks like the pistons are not square in the cylnder. What would cause this? Thanks
Click to expand...

i thought pistons were round .

















haha, j/k

sorry, but I couldn't help on this one; so I figured that a smart a$$ remark was best
 

rd

Founding Member
Jan 12, 2000
3,316
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109
Ocean Springs MS
Sep 13, 2005
#4
  • Sep 13, 2005
  • #4
If you are looking at the engine with the heads off, there is a fair bit of movement available to the pistons. It is normal, especially on the pin axis, not quite so noticable on the rod bearing axis, but still enough to be visible. Should not be a problem.
 

ECU5.0

Banned
Jan 10, 2004
1,803
1
0
raleigh, nc
Sep 13, 2005
#5
  • Sep 13, 2005
  • #5
i think what he is talking about is the cylinder being out of round. thats what it sounds like to me at any rate
 

vristang

15 Year Member
Mar 31, 2005
4,933
101
124
Seattle
Sep 13, 2005
#6
  • Sep 13, 2005
  • #6
rd said:
If you are looking at the engine with the heads off, there is a fair bit of movement available to the pistons. It is normal, especially on the pin axis, not quite so noticable on the rod bearing axis, but still enough to be visible. Should not be a problem.
Click to expand...


The pistons are not round. This is due to the expansion characteristics of the piston material and the thickness of the material. Thicker material will expand more. In a round bore it will look bad, but it is fine. I was aware of this when I put my motor together, but had to double check all the dims before I felt safe putting it together.
 

giddyup306

Founding Member
Oct 22, 2002
3,041
2
59
Sep 14, 2005
#7
  • Sep 14, 2005
  • #7
Pistons are "cam" ground. The Skirts will not change while the other parts will expand .001-.003" to allow for heat expantion.
 
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