[NegativeGeForce]

I bought this piston ring kit from ebay and the 2 top ring gaps are perfect, but the oil rings have a little too much gap, .025 to be exact, the 87 spec is .022 and the 88 spec is .017 and the max spec is .045 so I was wondering if there would be any difference if I just went with these rings?

Also i was wondering about the oil ring expander. When i fit this ring in the bore there wasnt any gap at all. Is this a ring I should also gap?

Any help would be great...this is pretty much all that is stopping me from putting the piston rings on my pistons and putting it all together everything else is in perfect spec thanks

 

[mdr40z]

of course, if you can, you always want to be on the small side of the spec. You're gonna lose a few thousands on break-in so you might end up as bad as say 0.030 still within but not as small as you could be. Oh and make sure to check gap at the top AND bottom of the bore.
More important perhaps is making sure to stagger all the rings per the book. Expander is supposed to be like that but make sure it's upside right, with some rings it makes a diff. Good Luck

 

[NegativeGeForce]

whats the best way to orient the piston rings around the cylinder?

i guess this would be the best way?

http://www.cygnusx1.net/supra/library/TSRM/em/EM_90.gif

 

[Tony Mawad]

http://www.cygnusx1.net/supra/libra...M/em/EM_79.html
NegativeGeForce,
According to what I heard from one machinist that I talked to in person, I will recite to you what he told me, as I asked the same exact question you are:
The oil rings are merely to wipe down oil. He called them oil scraper rings. You do have two of them. The only thing that will happen is that you will burn a slight bit more oil than if the gaps were on the tigher side. He made it seem very slight at that.

truth or false, that is what he told me^

As far as positioning the end gaps, different mk3 manuals will say different things (even for same car). IIRC, the Chilton manual & the Haynes manual, have some differences where the gaps are positioned.
One thing is always uniform though: always position the compression rings (top ones) 180 degrees apart. Having them on the opposite sides ensures maximum compression & combustion pressures within the cylinders.

Also all end gaps are always in an X fashion. I believe you do this because at the X position, as opposed to a + positioning, you will have less wear on the rings & cylinders. For example, it would not be ideal to have a gap on the thrust side & the additional stress that is incurred there from the force of combustion. There is less stress on rings when position in an X.

 

[Justin727]

wouldnt take the advice out of the chilton and haynes, hit up the tsrm!

 

[Tony Mawad]

One of them IS directly copied off a TSRM.

I was merely stating that there are differences that may not mean too much.
And in the process, also trying to stress the most important things to keep in mind (which are the constants).

 

[Justin727]

Indeed Tony!

 

[NegativeGeForce]

do i need to gap the oil ring expander?

 

[Tony Mawad]

I will summon a machinist to this thread.
PMing him now for you.

Although a GUESS is that the expander should not be touching the bores...I did say guess.

 

[NegativeGeForce]

thanks alot...i dont want to screw this engine up. The tsrm or haynes manual says nothing about gapping the oil ring expander yet it seems to fit kinda tight

 

[sponsored1]

The oil ring itself is comprised of 3 pieces, the main scraper, and the 2 retaining rings. The main purpose of the 2 rings is just to hold the scraper ring in place. And yes the scraper should have some tension on it when you place it in the bore. There are different types of ring sets, high tension, low tension, ect... You'll be fine with the gaps you have now. And the picture posted about the way to face the ring gaps is a good example.

 

[NegativeGeForce]

that helps alot...so my oil ring expander fits around my bores with a slight tension...thats ok?

 

[sponsored1]

thats what they should do. Slight tension = Good.

 

[NegativeGeForce]

ok thanks alot! Also one more thing...ive got one piston in right now actually exacly how you explained it should be and when i turn the crank theres a slight drag felt and a WOOSHING sound and theres slight abrations on the cylinder walls verticaly...thats all normal? lol i know im being anal but i want it perfect and this is my first time building an engine

 

[sponsored1]

there should be some tension when you crank it over, it still has to be broken in, but you shouldn't have any scratches, slight marks probably, but if you have some major scratches, chances are you might have pinched one of the oil retaining rings when you put the piston in. You have to be super careful, and make sure you pour some oil around the oil expander ring before you put it in.

 

[Tony Mawad]

Before he posts, I just want to say that when you put the piston in, make sure you dont spin them, as that will change the ring positioning. I think the rings will stick to the bores more than they will to the pistons, and will spin if you dont put them staight in.

I am sure you know that though, but just want to mention it.

 

[NegativeGeForce]

what about this?

 

[sponsored1]

looks fine. those just look like scuff marks, not scratches.

 

[NegativeGeForce]

yah once the engine runs it should wear the high spots on the rings and come to a good polish on the cylinder walls and a tight seal so these scuffs dont mean much...

thanks alot for everyone's help maybe this can help others in their rebuild quest

 

[Twigger]

Just to clarify, the bottom ring is the oil control, middle ring is the carbon scraper ring and the top is the compression ring.