How tight is your Jab 3300 Hot vs Cold

[Yenn]

If your engine is tight when cold and tighter when hot, what is the problem? If it is too tight it is not going to last long, something will sieze and it becomes a tear down job. if it is tight, but not too tight, it will gradually ease up. Too tight and the temps go up, power goes down, trouble.

 

I don't understand how direction can affect compression, by direction do you mean turning in the wrong way, if so you are compressing on the reverse of the power stroke and will not get a full charge.

 

 

[facthunter]

You will get very close to the same Yenn. The reason for turning it both ways is that if two comp ring grooves are on the one side it will have more effective sealing one way than the other.

 

Going to the excess ring wear with chrome? rings I would expect there could be some concern running that material on 4130 cylinders I also think there could be some concern with the 3 piece rings used in the oil groove. There are often scratch marks and blue heat marks in Jab cylinders. The scratches to me indicate a lube problem or incompatible materials. I feel the oil rings are too severe. I would stick to the w-100 plus oil with avgas .Nev

 

 

[frank marriott]

"I would stick to the w-100 plus oil with avgas .Nev"

 

Nev - this is what the manufacturer recommends as well.

 

Use whatever you like, but I prefer to go with manufacturer's recommendation. My approach is they would know more about their engine then me, I only fly them.

 

 

[bexrbetter]

I'm a little late with this one.....I have built many engines over the years and I always keep the ring gaps 120 deg apart including the 3 piece oil rings, they don't hold compression but they do hold oil.

I also keep the gaps away from the thrust faces as much as possible.

Facthunter is quite correct, rings rotate in the bores and it varies greatly and can't be proved at what speed they will do so but average out to about 3 rpm per 1000 rpm. The more they rotate the more life you get as the wear is spread evenly over the bore and ring and is one of the reasons a pegged 2 stroke ring wears faster.

 

Can win many Friday night beer workshop arguments with that one because it's SAE documented.

 

But it's good to have minimum leakage on new startup so nothing wrong with the practice of spacing them.

 

 

[facthunter]

W-100 plus....It's formulated for the tetraethyl lead. It also has a camshaft friction modifier and some stuff in it to stop corrosion when stored and it is a certified aircraft oil plus as you say it is recommended by the maker of the engine. I have paid less for it than a lot of other less "reliable" oils cost. Nev