Ring end gap preference

[Ironmike]

Did all the 1/2 inch drilling for oil system, deburred the whole block and decided to start filing my rings.

I gapped the top rings at .019, per Total Seal. They are not the gapless type. I personally have always gapped the second ring the same, again, per Total Seal.

I keep reading how some guys go a couple thou bigger on the second ring to reduce ring "flutter". Wonder how many of you go this route.

 

[moper]

I do it on everything I build. I add .001 per inch of bore. The additional gap in the 2nd ring allows pressure between the top and 2nd rings to escape while maintaining ring control. The 2nd ring is only an oil scraper, by design it is not a compression ring, so there's no down side to providing the 'room".

 

[yellow rose]

I do it on everything I build. I add .001 per inch of bore. The additional gap in the 2nd ring allows pressure between the top and 2nd rings to escape while maintaining ring control. The 2nd ring is only an oil scraper, by design it is not a compression ring, so there's no down side to providing the 'room".

This^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^




That's why gapless second rings had some issues in some cases. The gases would get caught by the second ring and unseat the top ring.

 

[yellow rose]

What are you using for a cam? If you are using a solid lifter you can tube the passenger side and cut the oil off to the drivers side. That's a big help.

 

[Ironmike]

What are you using for a cam? If you are using a solid lifter you can tube the passenger side and cut the oil off to the drivers side. That's a big help.

Bullet solid roller. About a week away. Lifters are MRL pressure oiled roller, so don't think I can tube the galleries. Gotta have oil to the roller. I just won't run a roller lifter that's splash oiled.

I would have loved to bush the bores, but after a grand in machining, I just can't see throwing another 700 bucks at a factory block. Mikes lifters usually work well far as the oil puking issue some of us have when going roller. They are basically a Morel, made by BAM products. .....who left Morel awhile ago.

 

[yellow rose]

Bullet solid roller. About a week away. Lifters are MRL pressure oiled roller, so don't think I can tube the galleries. Gotta have oil to the roller. I just won't run a roller lifter that's splash oiled.

I would have loved to bush the bores, but after a grand in machining, I just can't see throwing another 700 bucks at a factory block. Mikes lifters usually work well far as the oil puking issue some of us have when going roller. They are basically a Morel, made by BAM products. .....who left Morel awhile ago.

I just drill a an .062 hole in the tube and that lubes it. The drivers side is a bit different. I was going to tube the DS on a junk block to see how it would go for cases just like this.

But...I don't know how much oil those lifters need. My plan may not work to keep the lifters fed.

 

[Ironmike]

Like to do some experimenting myself some day. I do have a nice junk block to fart around with. Nice little cracks from the lower headbolt holes right to water jacket.

I don't think they need a lot of oil, but do need steady pressure. I can't believe some guys will run a roller lifter with a splash lubed roller. I guess it's different for a race only motor. Sure wouldn't wanna idle it much, though.

To each his own, I guess.

 

[Ironmike]

Almost forgot. Talked to my machinist today......running the same gap on 2nd ring as top. According to him, the days of old heavy pistons and thick rings are gone. No need for a wider gap. He told me he didn't even believe the whole "flutter" theory below about 9000 rpm.

As above.....to each his own..

 

[yellow rose]

Almost forgot. Talked to my machinist today......running the same gap on 2nd ring as top. According to him, the days of old heavy pistons and thick rings are gone. No need for a wider gap. He told me he didn't even believe the whole "flutter" theory below about 9000 rpm.

As above.....to each his own..

I agree with the flutter issue. Thin rings and gas ports all but eliminated that.

The issue for me is no matter what, you will never get 100% seal. Something is going to get by the rings. The best place for that pressure to go is onto the crank case. If that pressure stays above the second ring, at higher engine speeds, the cumulative gasses can unseat the top ring.

That's why I'm a big proponent of vacuum pumps on street cars. A negative pressure in the crank case makes it easier to handle what blow by you get. In my case, I can't fit a pump in my car without a ton of work, so I bought a Wagner adjustable PCV valve and run pan evacs over it. I'm going to test when the weather gets above 11 degrees during the day and at least some of the snow goes away. I am going to test how much crank case vacuum I can pull at idle with both systems, each system separate, and then the same thing at a cruise and WFO.

There is always some combustion past the top ring.

 

[moper]

"The issue for me is no matter what, you will never get 100% seal. Something is going to get by the rings. The best place for that pressure to go is onto the crank case. If that pressure stays above the second ring, at higher engine speeds, the cumulative gasses can unseat the top ring."

x2. And depending on the accuracy of the bore, the pistons, the rings used, and the wall finish that rpm can be a lot lower than 9K... a LOT lower.

 

[Ironmike]

I agree with the flutter issue. Thin rings and gas ports all but eliminated that.

The issue for me is no matter what, you will never get 100% seal. Something is going to get by the rings. The best place for that pressure to go is onto the crank case. If that pressure stays above the second ring, at higher engine speeds, the cumulative gasses can unseat the top ring.

That's why I'm a big proponent of vacuum pumps on street cars. A negative pressure in the crank case makes it easier to handle what blow by you get. In my case, I can't fit a pump in my car without a ton of work, so I bought a Wagner adjustable PCV valve and run pan evacs over it. I'm going to test when the weather gets above 11 degrees during the day and at least some of the snow goes away. I am going to test how much crank case vacuum I can pull at idle with both systems, each system separate, and then the same thing at a cruise and WFO.

There is always some combustion past the top ring.

I'm pulling 5 inches at idle(1250)with just header evacs on the motor I ran last year, currently still in the car. Seems like a lot, but I checked it a couple times.