need some advice..
Thread Starter
Teching In
Joined: Oct 2015
Posts: 46
Likes: 0
From: Central Texas
need some advice.. Ok,
so full disclaimer, I screwed up.
I haven't build an engine that didn't use dished or flat top pistons and with my current build I used forged JE pistons with 2cc relief cuts in them. I believe I've installed the pistons upside down. The fly cut is on the bottom of the engine instead of the top. To be clear, the choice for these pistons was not valve clearance. It was merely a forged piston that was in the correct size for my Iron LS1 build and it worked with the LS2 rods i'm using. The shop that installed my rods onto the pistons told me that for LS2 rods the casting dimple in the center points to the front of my engine. So that's what I did.
My Cam is the Z06 5308 cam. Not large at all and shouldn't be an issue for PTV clearance.
My question is this. Can I just remove the oil pan, windage tray and rotate the rods to correct orientation? Or will I have to remove the heads...
Or should I leave it alone since its not hurting anything?
I just torqued new head bolts on and was going threw old photos of my build and seen this.
so full disclaimer, I screwed up.
I haven't build an engine that didn't use dished or flat top pistons and with my current build I used forged JE pistons with 2cc relief cuts in them. I believe I've installed the pistons upside down. The fly cut is on the bottom of the engine instead of the top. To be clear, the choice for these pistons was not valve clearance. It was merely a forged piston that was in the correct size for my Iron LS1 build and it worked with the LS2 rods i'm using. The shop that installed my rods onto the pistons told me that for LS2 rods the casting dimple in the center points to the front of my engine. So that's what I did.
My Cam is the Z06 5308 cam. Not large at all and shouldn't be an issue for PTV clearance.
My question is this. Can I just remove the oil pan, windage tray and rotate the rods to correct orientation? Or will I have to remove the heads...
Or should I leave it alone since its not hurting anything?
I just torqued new head bolts on and was going threw old photos of my build and seen this.
On The Tree
Joined: Dec 2011
Posts: 118
Likes: 0
From: Colorado Springs, CO
You should be able to rotate the pistons from the bottom end without any issues. My only concerns would be: how sure are you that ALL the pistons are badly oriented? Also, if you rotate them, would that mess up the dimple that your machine shop was talking about?
For the record, I'm not sure about the dimple at all as I've never done anything LS2 related
Hope this helps
For the record, I'm not sure about the dimple at all as I've never done anything LS2 related
Hope this helps
Thread Starter
Teching In
Joined: Oct 2015
Posts: 46
Likes: 0
From: Central Texas
So the dimple debate has been going on a while. Their more of it on the GenIV section. But I'm under the impression that both sides of the rods are machined and it does not matter the orientation. I'm 100% sure all rods are in the same direction. My biggest concern is ring movement when I rotate the piston 180* is their a large chance of the rings lining up.
This is interesting. Sounds like something I would screw up myself. Probably twice. 
Seems to me that the rings will have more tension against the bore than the piston..so perhaps if you ever so slightly "lift" the piston just to take the force of gravity on the piston off the rings when you spin, the rings should stay put and the piston should rotate.
It occurs to me that anyone with a disassembled engine could test this theory.
Seems to me that the rings will have more tension against the bore than the piston..so perhaps if you ever so slightly "lift" the piston just to take the force of gravity on the piston off the rings when you spin, the rings should stay put and the piston should rotate.
It occurs to me that anyone with a disassembled engine could test this theory.
Thread Starter
Teching In
Joined: Oct 2015
Posts: 46
Likes: 0
From: Central Texas
I have some info on my pistons. But I wont know for sure until i drop the pan and take a look.
Can you tell me if this model has a thrust side?
JE Part number#321240
Last edited by Shaggykjb; Mar 7, 2016 at 04:15 PM.
TECH Resident
Joined: Apr 2014
Posts: 985
Likes: 12
In the pic. with both pistons you can see how the top is larger than the other top.
with single pic. maybe you can see the left and the right.
I looked at the website jepistons. but really could not tell if yours
are sided.
with single pic. maybe you can see the left and the right.
I looked at the website jepistons. but really could not tell if yours
are sided.
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I had an engine once with upside down pistons like that.
I didn't have it very long, but one thing I noticed when I tore it apart, some of the valves made contact with some of the pistons. Maybe the valves floated at some point; it was in a turbo/daily. Point is, if the pistons werent upside down, those valves likely would have never kissed those pistons, and gotten bent. They might not touch now, but, given the chance they might have an opportunity.
I didn't have it very long, but one thing I noticed when I tore it apart, some of the valves made contact with some of the pistons. Maybe the valves floated at some point; it was in a turbo/daily. Point is, if the pistons werent upside down, those valves likely would have never kissed those pistons, and gotten bent. They might not touch now, but, given the chance they might have an opportunity.
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