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TR2/3/3A TR3 Piston Orientation

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MGTF1250Dave

MGTF1250Dave

Jedi Knight
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Aloha,

I am about to reassemble my TR3 engine. It has 87mm sleeves and pistons that I am reusing. I know I need to install the con rods offset towards the camshaft side of the engine. I can not find any markings on the piston to indicate the front side. "STD" is stamped into the top of piston and is perpendicular to the axis of the wrist pin. Cast inside the piston in a raised logo "AE" which I believe is the manufacturer. Do I need to be concerned about this or is the wrist pin centered in the piston?
 
I would install the pistons exactly as they were when you took them out. They may have ovaled some, and the liners as well.
 
For the most part what I have found is the STD, .010, .020, etc is usually towards the front of the engine and used as the orientation mark. That being said I have found some that havn't been. If you look closely at the pistons there is usually a little more wear on one side over the other due to the angle of the rods on the power stroke pushing the piston the other way against the cylinder. Hope it helps.
 
I would have to look at it to be sure Dave and I kinda remember asking the same question, but I think they can only go in one way and still be able to travel around because of the off set in the rod.
Steve
 
Since you have 87mm pistons they would be aftermarket and perhaps different so this might not apply but the original pistons had the expansion kerf (slit) on the side opposite the cam. My crude measurements show that then pistons are otherwise symmetrical and the pin is centered. Any machine shop can confirm that. You do not need to match the wear of the liner as these are sometimes purposely turned 1/4 turn to even out the wear. Tom
 
Aloha,

Thanks for the replies. I guess I should have have asked if the 87mm pistons had the wrist pin centered in the piston. I'm still tring to determine this, but I can determine that one side does have a shiney wear marks and now know I should have marked the "front" myself before disassmbling the engine. So, lve and learn.
 
sp53 said:
I would have to look at it to be sure Dave and I kinda remember asking the same question, but I think they can only go in one way and still be able to travel around because of the off set in the rod.
Steve
Click to expand...

I Remember, when i rebuilt my first motor, TR4a, I put them con rods in with the wrong orientation, because the liners are held in by the head I did not spin the motor until the head was back on, luckily I was spinning it by hand, this was quite some time ago, but I still remember it was quite the WTF moment until I figured out the problem, not too hard as I recall I still had the oil pan off.
 
Back in our broke college student days(daze?)we would pull the liners, turn them 90degrees and drop them back in.This kept the pistons from slapping and sometimes the rings would even seat for a while!!!!
The moral is that these old girls could (and did) take a lot of back yard mechanicing and keep on running in spite of it!
I have in the garage an old motor done that way 40 years ago.It has the pistons out of my first TR3 in it.They were installed in a parking lot at Sin-city in 71...lots of beer,very few new parts.It ran like stink till it was wrecked,then put into a TR2 that was latter wrecked also....Cant throw it away NOW can I???
MD(mad dog)
 
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