1950 mercury Flathead Engines
 

I cant seem to find any thing on the Mercury pistons that have the expansion slot in them. I need to know when you install them in the engine does the slot face the Thrust side of the cylinder wall or towards the intake. The engine I took apart was 50/50 2 one way 2 the other way. Those 4 pistons were burnt with a hole on the thrust side of the pistons. I would think the piston slots would need to be all one way not random. I need a Flat head expert to answer this. I have rebuilt lots of Ford engines but never a Mercury with these pistons ,

A picture or two would be nice. By slot, would you be referring to the chip taken out of the piston face that is on the thrust side to clear the head?

Or, try this: http://www.hotrod.com/techarticles/e.../photo_15.html

No
 

the side of the piston has a long slot cut right into it. it is an expansion slot and only on one side of the piaston all 8 have this all mercury engines have this from 1949 on

If no answer
 

i'll take a photo tomorrow but a Flat head man would know this I would think

Mark the spot on the picture below.

Some of the smartest flathead guys hang out at the HAMB, try there then.

Last time, check the pic.

1950 Mercury
 

Hers some photos of the slots in the Mecury pistons 2 of them were on the thrust side with numbers on the rods facing out. And the other 2 were facing the intake side with the numbers on the rods facing out.

1950 mercury
 

pistons with the slots on them

As you know the oil squirt holes should face inward... I have never seen expansion slots like that... must be an aftermarket piston?

Nope
 

Standard Mercury pistons because on the increased stroke Ford original

>>true about the oil hole but you can pin these pistons either way my engine had 2 going one way and 2 going the other way. i think a shade tree mechanic did the engine at one time. After Ford sold it

Many pistons have a mark, notch, arrow, etc. to show "front" of the piston.

In your case, the photo shows how the pistons are installed:

http://www.hotrodders.com/gallery/da...rientation.jpg

EDIT- The photo above shows a basically stock piston, if you look closely you can see the front orientation on the crown, pointing to the left. The last photo (I removed it and replaced w/this one) I'm unsure of the way the slot was slanting- but it should have been correct anyway.

Unless there are "left bank" and "right bank" pistons, one bank will have the slot on the major thrust side, the other bank will have the slot on the minor thrust side.

So unless there is a pin offset or a relief in the piston crown facing the valves, it really doesn't matter how they're installed, IMO.

Good Thanks
 

Now I wont have to worry when i put others back

The reason
 

I was concerned about the orientation of each piston and the slot. 2 pistons on each side had a burn hole through to the top ring. The only other odd thing I found was in the chambers of the head, on each head I found a square bump in the chamber casting right in front of the spark plug hole on the thrust side in all 4 pistons. Is it possible the bump impeded the flame travel and over the miles it burned a hole through all the pistons where the chamber had these bumps. The other 4 chambers did not have these bumps.