That Fourth Piston Ring Again? 8BA

L

leon bee

Well-known member
Flathead newby here. Soon will be fitting the rings and getting pistons ready. I read all the old posts I can find: I want to delete that bottom ring on my 8BA but I get nervous. One day I was looking thinking, man, that is a long tall piston. What if the bottom oil ring helps keep her lined up in there? Then to add to that I even read the same concern expressed somewhere else.

So, I know Tubman and many of the rest of you frequent advisors leave em out, but maybe I need some hand holding on this. Or put em in?

This Ford Barn is my favorite place on the net these days.
 
The lower ring has nothing to do with piston stability! It's for oil control. The second oil ring was there because of the ring technology at the time, with modern oil control rings it is not required and only serves to increase piston drag.
 
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If you are racing the engine from my standpoint leave it off, or buy some racing pistons for that type of operation, as for me and a driver I use it and leave adequate clearance .my thinking is the long term effect of leaving out parts, I know that ring technology has advanced somewhat but Henry went to the 4 rings as an improvement to stop oil consumption , no doubt there will be a little more drag on the pistons which equates to wear but if it has a place for 4 rings I use 4 rings.
 
I don't want to cause any more stress but the steel Pistons use only 3 rings . If it's only function is to control oil , why wouldn't the steel Pistons have 4 rings ? This specified clearance is the same for both steel and aluminum .
If it has a groove for a ring I would use it . But my curiosity is getting me .
 
Ggmac said:
I don't want to cause any more stress but the steel Pistons use only 3 rings . If it's only function is to control oil , why wouldn't the steel Pistons have 4 rings ? This specified clearance is the same for both steel and aluminum .
If it has a groove for a ring I would use it . But my curiosity is getting me .
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The rings float in the piston ring grooves, they do not support the piston, they are for oil control. The real answer would be to not use the four ring pistons in the first place! LOL But if you have them or want to use them, it's up to you. The forth ring gains you nothing and has some down sides. But on the other hand the down sides are somewhat minor, so up to the user.
 
I agree the ring does not help center the piston in the bore . I'm just curious why would ford at the same time , have Pistons with both 3 and 4 rings .
I've never left the 4 ring off mostly because I was the employee and the boss hated having parts left over ! I guess I just followed his style . Never have built 2 identical engines to test for myself the difference in wear between the 3-4 ring .
At this point , I'd be happy , make that thrilled , if I get to drive one of mine a few hundred miles a year so either will work .
 
Stick all the pistons in a lathe and cut off the ring grove, or buy good new pistons with the metric ring pack
 
"Kahuna" - Just curious, wouldn't removing that much material from the piston affect the balance? Would it make it harder to balance?

I am a proponent of leaving off the fourth ring, but only on new engines that will be balanced before assembly. If I was just replacing a set of stock pistons, I think I would run the fourth ring. I would make the decision after weighing the new/old pistons and rings.
 
I think Kahuna machine it off comment was jest. If anyone is that hung up on this forth ring issue, just run the thing! Kahuna second comment is the best suggestion, get another set of pistons so you won't have nightmares about a none required ring!! :)
 
19Fordy said:
Has anyone ever filled in the 4th piston ring by welding it?
Then turn down the OD in a lathe.
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Sounds like a lot of work to chase the nightmares away...lol
A piston isn´t round so unless you have an old piston grinder or a CNC lathe with a c-axis it isn´t so easy to machine them when done either.
Pistonrings and oil is now officially my favourite flathead minefields :D
 
Ggmac said:
I don't want to cause any more stress but the steel Pistons use only 3 rings . If it's only function is to control oil , why wouldn't the steel Pistons have 4 rings ? This specified clearance is the same for both steel and aluminum .
If it has a groove for a ring I would use it . But my curiosity is getting me .
Click to expand...

The early oil blower v-8 had 3 rings, steel pistons That is why we now have 4 rings. aluminum pistons. do a little research and talk to an okie who drove a ford v-8 to California in the dirty thirties. I have sat listened and learned a lot from my elders , all these years the same story was told about the early version of the ford v-8, overheating and oil consumption. in spite of it's drawbacks the ford v-8 was the way to go for the average person's mode of transportation.
 
Why is the fourth ring such a big deal. Just put it together with the fourth ring installed. What are you going to get by leaving it off? 1 more horse power? Your going to save life of the bore with reduced drag on the cylinder because you rack up 15,000 miles a year on your flathead engine? Is it really worth the time and expense to weld up the ring groove then turn the piston down. This all seems a bit silly. This is a non issue to me.
 
flatheadmurre said:
Sounds like a lot of work to chase the nightmares away...lol
A piston isn´t round so unless you have an old piston grinder or a CNC lathe with a c-axis it isn´t so easy to machine them when done either.
Pistonrings and oil is now officially my favourite flathead minefields :D
Click to expand...

I agree here.
 
flatjack9 said:
I don't think that ring would make a serious difference in balance.
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From what I can find out, one piston ring runs between 15 and 25 grams. Given that performance shops aim for 0.5 -1.0 grams of imbalance, can you explain your thinking?
 
Well that bottom ring sure scrapes its share off the cylinder wall. Today we have oil squirters aimed at the bottom of pistons to cool them off thus allowing higher compression ratios.

I think more oil and less heat are a good thing so long as we keep it under control.

Oils are the big difference I think. Those heavy "motor honey" oils they used in the early days probably overcame the ring's ability to control it. The rings could have actually glided on the surface of that molasses instead of scraping it off.

Today's oils don't need that.
 
So much for the hand holding! I thought I'd read somewhere I'd get 8 more HP leaving them out: read it on the internet, has to be true!
 
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