That Fourth Piston Ring Again? 8BA

[flatjack9]

Originally Posted by tubman

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?

You are removing the same amount from each piston. The 0.5 to 1.0 you are talking about is a variance between pistons. Besides, balancing is basically more of an art. Different balancers have different ideas as to what the balance should be.

[flatjack9]

I know when I build an engine, there is a marked difference in the drag between 3 and 4 ring pistons. That is a good enough reason for me. To each his own.

[tubman]

Originally Posted by flatjack9

You are removing the same amount from each piston. The 0.5 to 1.0 you are talking about is a variance between pistons. Besides, balancing is basically more of an art. Different balancers have different ideas as to what the balance should be.

Thank you. Makes perfect sense.

[deuce_roadster]

If you think that there is some stability issues (which I don't) leave off the 3rd ring and leave the 4th. You don't need 2 oil rings.
To me the extra wear on the cylinders is unwarranted. There is no doubt there is extra friction if you use all 4.

[tubman]

IIRC, the last set of Speedway four ring pistons I got had a 3 piece oil ring in the third groove, and a regular cast iron ring in the fourth. If this is the case,, I don't know if switching them around (even if they fit), would be a good idea.

[rotorwrench]

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Look into these but be prepared to go oversize since they start at .125" OS. https://egge.com/part/egg-1000-ep1091-8/

[Henry Floored]

If anyone would like to know all there is to know about piston rings and oils and how they interact I strongly suggest you call the "tech line" at Hastings Piston Rings.

Ask for the lady, I think her name may be Betty. Ask a basic question regarding this subject and just sit back and listen.

You will learn more in 10 mins about this stuff than some do in a lifetime. Trust me on this.

[flatheadmurre]

Originally Posted by flatjack9

You are removing the same amount from each piston. The 0.5 to 1.0 you are talking about is a variance between pistons. Besides, balancing is basically more of an art. Different balancers have different ideas as to what the balance should be.

In a V engine you can´t just take off the same amount of each piston and keep the balance in the engine...works on a 4 cylinder.

[Kahuna]

JSeery is correct. I was just joking.
If you just want a stock engine and have the 4 ring pistons, then use them & forget the 4th ring.
I don't build stock engines & am always interested in gaining as much improvement as I can. Thus the comment re new modern pistons with the metric thin rings. To me, friction is your enemy.
Jim

[Ronnie]

Originally Posted by Henry Floored

If anyone would like to know all there is to know about piston rings and oils and how they interact I strongly suggest you call the "tech line" at Hastings Piston Rings.

Ask for the lady, I think her name may be Betty. Ask a basic question regarding this subject and just sit back and listen.

You will learn more in 10 mins about this stuff than some do in a lifetime. Trust me on this.

Yup x 2^^^^ Ask me how I know

R

[40 Deluxe]

If one insists on using 1930's oil ring technology (one piece oil rings), you will need two oil rings. If you go with modern three piece oil rings, that antiquated 4th ring is a waste. Leave it out.

[deuce_roadster]

I am curious, just how many people use the old pistons that have 4 ring grooves? Every flathead I have rebuilt (5, not counting ones done when I was a teen) has Ross pistons with modern rings and were honed to specs for those new skinny rings. When there is something better I tend to use it.

[JSeery]

Originally Posted by 40 Deluxe

If one insists on using 1930's oil ring technology (one piece oil rings), you will need two oil rings. If you go with modern three piece oil rings, that antiquated 4th ring is a waste. Leave it out.

Well put!

[tubman]

Originally Posted by flatheadmurre

In a V engine you can´t just take off the same amount of each piston and keep the balance in the engine...works on a 4 cylinder.

Hadn't thought of that; now I'm even more confused. I'll still leave off the forth ring and have the rotating assembly balanced.

[leon bee]

Originally Posted by deuce_roadster

I am curious, just how many people use the old pistons that have 4 ring grooves? Every flathead I have rebuilt (5, not counting ones done when I was a teen) has Ross pistons with modern rings and were honed to specs for those new skinny rings. When there is something better I tend to use it.

I pretty much agree with you, but I like old technology as well. This is my learning Flathead. I do vintage motorcycles mostly, put dozens of those old cast iron ring engines back on the road.

My machine shop guy, who I feel blessed to have found, got me a rebuild kit and it has these Sealed Power pistons which look just like originals. Couple months I'm gonna go get me a Mercury engine..........it'll have newer style parts going in it.

[rotorwrench]

I am a street driver so the forged pistons are one of those items I forgo. I've had better luck over the years with cast pistons for longevity and average driving. For performance, the forged are likely the way to go but most folks that push things to the limits are prepared to work on things more and pay more for the things that work.

[petehoovie]

Friction from the 4th ring is not an issue if you add 'SLICK 50' to your oil!....

[Ol' Ron]

I do not use the bottom ring. I also cut the bottom of the piston off to lighten the piston.

[leon bee]

Okay, I'm gonna leave em out.

[4 MAINS V8]

Apologies in advance for prolonging this question,however, just found this information in a box of nos pistons. Could this be the definitive answer from one of the largest piston manufacturers in the world.