The Ford Barn

Brendan1959 · 08-10-2020, 01:47 AM

Can anyone tell me which way the split in the piston faces, I marked the cap but not the rod (fool).
They must have had an issue finding piston rings at the last rebuild, Have a close look.

dave in australia · 08-10-2020, 02:00 AM

Some, but not all, pistons are marked on the top which way is forward.

Richard in Anaheim CA · 08-10-2020, 02:24 AM

1. Flat part up

2. Split toward cam

Brendan1959 · 08-10-2020, 04:15 AM

Thanks
No stamps on the top
split to cam will hep
Brendan

katy · 08-10-2020, 10:15 AM

The split goes opposite to the thrust side.

Bob C · 08-10-2020, 11:06 AM

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I've seen that before where they run three rings on four groove pistons.

Brendan1959 · 08-10-2020, 06:29 PM

I count 11 piston rings

Brendan1959 · 08-10-2020, 08:40 PM

If the pistons are supposed to have the split to the cam then they must have been in the wrong way round!

1930-Pickup · 08-10-2020, 11:54 PM

Quote:

Originally Posted by Brendan1959

If the pistons are supposed to have the split to the cam then they must have been in the wrong way round!

A few years back I had a 1925 Dodge Brothers roadster. Someone in the past had put all the piston split skirts in the wrong direction.

I was driving to work one day and...KER-BLAM-tinkity-tink-tinkle! One piston disintegrated and it rained small crumbly bits as gravity sucked them into the bowels of the engine.

Too fun.

Dodge · 08-11-2020, 01:33 AM

They probably cut the ring grooves and added spacers to save the pistons.
In any case those pistons have been more than once around the block.

Kurt in NJ · 08-12-2020, 08:18 AM

According to the service bulletins the split goes to the left side(left/right determined from drivers seat)
This makes the camshaft side the thrust side that has the solid skirt,

rotorwrench · 08-12-2020, 09:01 AM

The direction of rotation sets the thrust side. When a connecting rod is going down on the power stroke in a clockwise rotating engine (as viewed from the front), the piston thrusts the opposite direction. In the case of the model A, the thrust side is toward the valve chamber. Split skirts are for piston expansion as they heat up but that spit is a weak point on the skirt so you don't want the split on the thrust side.

abachman3 · 08-12-2020, 10:45 AM

I recently took apart a motor at the museum and it had two pistons facing each way... guess they were doubling down that at least they would be half right!

Kurt in NJ · 08-12-2020, 02:37 PM

For my smiths compresser I switched #2,3 because the thrust is on the upstroke for the 2 air compressing pistons

08-10-2020, 02:24 AM	#3
Richard in Anaheim CA Senior Member Join Date: May 2010 Location: Anaheim California Posts: 562	Re: Piston orientation 1. Flat part up 2. Split toward cam

08-10-2020, 04:15 AM	#4
Brendan1959 Member Join Date: Jul 2010 Location: Melbourne Australia Posts: 95	Re: Piston orientation Thanks No stamps on the top split to cam will hep Brendan

08-10-2020, 10:15 AM	#5
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,712	Re: Piston orientation The split goes opposite to the thrust side. __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

08-10-2020, 11:06 AM	#6
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 9,359	Re: Piston orientation Sponsored Links (Register now to hide all advertisements) I've seen that before where they run three rings on four groove pistons.

08-10-2020, 06:29 PM	#7
Brendan1959 Member Join Date: Jul 2010 Location: Melbourne Australia Posts: 95	Re: Piston orientation I count 11 piston rings

08-10-2020, 02:00 AM	#2
dave in australia Senior Member Join Date: May 2010 Location: Victoria, Australia Posts: 1,241	Re: Piston orientation Some, but not all, pistons are marked on the top which way is forward.

08-11-2020, 01:33 AM	#10
Dodge Senior Member Join Date: Nov 2011 Location: Sonoma, CA. Posts: 1,568	Re: Piston orientation They probably cut the ring grooves and added spacers to save the pistons. In any case those pistons have been more than once around the block.

08-12-2020, 08:18 AM	#11
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,554	Re: Piston orientation According to the service bulletins the split goes to the left side(left/right determined from drivers seat) This makes the camshaft side the thrust side that has the solid skirt,

08-12-2020, 09:01 AM	#12
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 17,410	Re: Piston orientation The direction of rotation sets the thrust side. When a connecting rod is going down on the power stroke in a clockwise rotating engine (as viewed from the front), the piston thrusts the opposite direction. In the case of the model A, the thrust side is toward the valve chamber. Split skirts are for piston expansion as they heat up but that spit is a weak point on the skirt so you don't want the split on the thrust side.

08-12-2020, 10:45 AM	#13
abachman3 Senior Member Join Date: Jun 2013 Location: Western Springs, IL Posts: 324	Re: Piston orientation I recently took apart a motor at the museum and it had two pistons facing each way... guess they were doubling down that at least they would be half right!

08-12-2020, 02:37 PM	#14
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,554	Re: Piston orientation For my smiths compresser I switched #2,3 because the thrust is on the upstroke for the 2 air compressing pistons