EVO piston orientation
Tourer
Joined: Aug 2014
Posts: 302
Likes: 49
From: Gambrill, MD
I think it is a piston used on early Evo`s, I think they had bigger valve reliefs in them.
According to the FSM, the raised area on the wrist pin boss is the left side of piston.
Remember, OEM pistons are the same for front and rear, don`t go by valve reliefs
The wrist pin is slightly offset, that is what makes the orientation of the piston critical.
OEM pistons use the raised portion on the pin boss to denote the left side of piston, later part number OEM pistons use an arrow to denote front.
This piston has both markings...
According to the FSM, the raised area on the wrist pin boss is the left side of piston.
Remember, OEM pistons are the same for front and rear, don`t go by valve reliefs
The wrist pin is slightly offset, that is what makes the orientation of the piston critical.
OEM pistons use the raised portion on the pin boss to denote the left side of piston, later part number OEM pistons use an arrow to denote front.
This piston has both markings...
"The arrow on top of the piston points to the front of the engine"
-Dave
Seasoned HDF Member
Joined: May 2008
Posts: 20,996
Likes: 12,523
From: South Carolina
Not sure why he came here and asked...
Last edited by Dan89FLSTC; Jul 20, 2020 at 11:13 AM.
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Intermediate
Joined: Jun 2020
Posts: 27
Likes: 4
From: crawfordville
I came here for advice. i got different opinions here that were more confusing. I was sure the arrow went to front but after they showed up with arrows marked all over then maybe i had something i had never seen before. I was just making sure i was right. They went in arrow to front. But i guess there are smart *** every were you go. Just looking for confirmation not smart *** comments.
Seasoned HDF Member
Joined: May 2008
Posts: 20,996
Likes: 12,523
From: South Carolina
You got conflicting instructions from the people who sold you the pistons, not from me.
I told you how they were supposed to go in, raised portion on wrist pin toward left, and arrow toward front.
You said the guy told you that the raised part on the wrist pin goes toward the cam, which was the opposite of what I told you.
Go back and read your own posts.
Now you are saying they went in with the arrow toward front (which is the way I told you from the beginning).
Bye
I told you how they were supposed to go in, raised portion on wrist pin toward left, and arrow toward front.
You said the guy told you that the raised part on the wrist pin goes toward the cam, which was the opposite of what I told you.
Go back and read your own posts.
Now you are saying they went in with the arrow toward front (which is the way I told you from the beginning).
Bye
Last edited by Dan89FLSTC; Jul 20, 2020 at 05:53 PM.
Ultimate HDF Member
Joined: May 2006
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From: Ohio
(What we have here is a failure to communicate)
Seasoned HDF Member
Joined: Mar 2010
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From: Poolville
It's not easy being a teacher some will listen and others will listen to too many and get confused.... As a novice it's hard to decipher between right and wrong... At times there will be conflicts We all have them... I'm just glad the OP put that one piston in that had the arrow pointing forward in the front cylinder pointing forward cuz that definitely was the exhaust valve relief from the top of that piston...
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From: Nor Cal
