Are the 3rd and 4th piston rings backward?

Cameron Koehn

Cameron Koehn

Member
I am tearing down a 1952 EAB that was rebuilt in 1974. Dropped the first piston out and it looked different than all the pictures I've seen. I continued and took the other 7 out and they were the same as the 1st. The bottom and the second from the bottom rings were installed in the other one's groves, or not?

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According to Hastings instructions, the first oil ring (top) is three piece, second one cast iron.
So yours look reversed.
 
Or . . . leave the second oil ring out altogether . . . it is really not needed. (I'm talking about the lower one). Use the 3-piece unit in the upper groove and don't install the lower.
 
Bored&Stroked said:
Or . . . leave the second oil ring out altogether . . . it is really not needed. (I'm talking about the lower one). Use the 3-piece unit in the upper groove and don't install the lower.
Click to expand...

After much thought and conversations on this and another board, I installed a set of new 4 ring pistons without the bottom ring in my last build. I had the assembly balanced with just three rings, and it worked fine.
 
I agree with Denny on the bottom ring on new pistons .

But,,,I’m not sure about original Ford pistons .
The old stock pistons were not cam ground like a modern piston .
I believe the fourth ring helped with oil usage,,,,,but it also helped stabilize the pistons while they were running,,,,kept them more steady in the bore .
At least that’s my feelings .

Tommy
 
Jack E/NJ said:
Look pretty good to me if has some mileage on it. Maybe instructions should be reversed. 8^).
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Ya, I'm not sure on the mileage. I bought the engine used not running, and hasn't run since the early 80's. It came apart real nice. It was stored inside the whole time. Everything was still coated with a film of oil.
 
In some engines, the 3-piece scraper is actually placed below the wristpin to also help stabilize a long skirt piston in the bore. Only compression rings are above the wristpin. The perforated stabilizer ring above the wristpin in this case probably could've been left out, maybe yielding better gas mileage. 8^)
 
Desoto291Hemi said:
I believe the fourth ring helped with oil usage,,,,,but it also helped stabilize the pistons while they were running,,,,kept them more steady in the bore .
At least that’s my feelings .

Tommy
Click to expand...

The fourth ring helped with oil control when one piece oil rings were the norm. Not needed with modern 3 piece oil rings.
As for a ring 'stabilizing the pistons....keeping them more steady in the bore', actually, no! A ring has to float freely in its groove to do its job. A stuck ring will not control oil. A free floating ring (which is what we need) cannot "stabilize" a piston! In reality, the piston stabilizes the ring! The ring has to be held square to the bore or it will not control oil. The piston is what holds the ring in its proper place.

This myth reminds me of another myth: That an engine will not start if all the ring gaps are lined up. Not true! Ring gap is so small compared to the space between ring lands that it does not matter where the gaps are. Besides, rings rotate in their grooves when the engine is running, so the gaps all randomly line up by themselves as the miles go by.
 
>>>That an engine will not start if all the ring gaps are lined up>>>


I never heard of that myth. 8^)
 
"40 De Luxe" has it right. The piston stabilizes the ring; not the other way around.

The key thing here is the "modern" 3 piece oil ring; as long as you have them, the bottom (fourth ring) is not needed.
 
I've come to the conclusion that superchargers and BOOST stabilize the rings . . . just kidding boys! What I will say is when was the last time you saw a 4-ring piston in ANYTHING (and I know the skirts are short - just work with me here!). If you're using a modern 3-piece oil-ring, there is no reason to use the 4th ring. Why have more friction and less HP than is necessary.

Also, one "modern" trend in flathead performance builds is to use metric rings that are a lot thinner and create less drag and HP loss. I usually build my engines with 1.5, 1.5 and 3.0 mm rings. Part of the reason is that I get much better modern ring materials (moly top ring), the other is less drag in the cylinders.

The other key factor is that it is really hard to find a lot of overbore sizes for our flatheads these days - so by going to metric rings, I have a LOT more selection - especially if I order custom piston sizes that correspond to the metric ring "normal" sizes.

I know - this is not "normal" standard rebuilding stuff - but it is important that we consider the universe of options . . . there are more than most imagine.
 
Yea, the thick solid one goes in the bottom groove. There are so many opinions on to run the fourth one or not, it’s pretty much personal preference. I left them off my build. My thought was extra weight and drag. They felt heavy to me.
 
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