Ring gap staggerin'

[John-T-53]

I know my posts are getting really specific, so sorry 'bout that....but I got another specific question. I wanted to get your thoughts on how much to stagger the piston ring gaps. When I put this ol' flathead together last fall, my machinist said to stagger the rings gaps at 10, 2, and 4, 8, compression and oil, respectively. When I pulled them suckers out a couple weeks ago (after 3k miles), the gaps had moved around a bit, and some of the oil ring gaps had lined up on a couple cylinders. (and it was smokin' dammit!!!).

Would it be better to stagger them 180 degrees from each other?

Edited April 13, 2010 by John-T-53

[HanksB3B]

but I seem to remember re-assembling mine some 20 years ago with my friend Slick (a machinist), who's Dad was rumored to be such a good mechanic than when Slick's 18 wheeler broke down was able to diagnose the problem over the phone. I swear I remember Slick instructing me to stagger the rings. Don't take my word for it, but it would seem that the purpose of rings is to trap gases not allow them to escape through a vertical slot.

I looked in the Dodge Truck Shop Manual and it doesn't mention anything about staggering.

Hank

P.S. I don't think you have to apologize for being "too-specific". My posts sometimes are all twisted up. It just shows people sometimes I don't know my *** from a hole in the wall. Glad to see you are getting your truck going again. How's the new job?

[John-T-53]

Yeah I checked the manual and nothing there too. This might be one of those topics where many opions abound but there's only one elusive correct answer.

Job is going good. I can walk to work and walk to everything else I need, except Napa Auto Parts, which is in the next town north about 3 miles from here. We're busy with all sorts of small projects which is rare for architects and everyone else in the building industry these days, but I'm hoping I can be held onto for at least a year which will help.

[4852dodge]

Years ago an old engine builder I know said to stagger the rings. I stagger the compression rings 180 if two rings and 120 if three, the oil rings at 180 each set. The top and bottom ring in each oil set opposite from each other to reduce blow by.

[Plymouthy Adams]

yes, stagger the ring gaps......the non stagering of rings on assembly was still a common problem on some factory cars..the last factory car that I remember having this problem was the 62 Rambler..but then that was so so long ago..

[MBF]

I don't know how true this is because I've never heard it before, but my machinist told me that rings will move or slowly rotate around the piston. That is supposedly what keeps them from sticking in the lands. Comments? Mike

[Plymouthy Adams]

ring does not move from my experience/reading..but I also have never had to disassemble an engine to verify this...is interesting though that on a two stroke engine there be locking anti-rotators in the piston..this could easily be food for thought or take the advice of the masters and just stagger the things and be sure you tithe regularly..

[JBNeal]

Years ago an old engine builder I know said to stagger the rings. I stagger the compression rings 180 if two rings and 120 if three, the oil rings at 180 each set. The top and bottom ring in each oil set opposite from each other to reduce blow by.

ditto...t'ain't nuthin' to keep them rings from rotating, but statistically it'll take a while for the rings to all line up if the gaps are far from each other.

[Merle Coggins]

I'm a firm believer that rings rotate and can possibly line up the gaps. I used to have an '84 Honda Gold Wing that would puff blue smoke, out of the left side pipe only, on startup when parked on the side stand. This would come and go from time to time. The only explaination I could come up with was that the rings would rotate around to where the gaps were all at the bottom (horizontal opposed 4 cyl engine). When parked on the side stand the oil on the cylinder wall could creep down past the rings into the combustion chamber, if the ring gaps were at the bottom. After a couple of days of this it would clear up for a while. (Ring gaps now away from the bottom or staggered enough to block the oil?)

I've always been taught that the ring gaps need to be indexed at 90 - 180 degrees. However, recently I was visiting a customer who was doing an in-chassis engine overhaul on one of their Volvo dump trucks. The cylinder kits came with the pistons already in the cylinder liners. The idea is that you can slide the piston down out of the bottom of the liner enough to install your connecting rod, then slip the whole assembly into the block. They were wondering how the rings gaps had been indexed so they pulled the pistons out and found that the ring gaps were all lined up on every piston. Apparently the engine manufacturer doesn't think the ring gaps need to be away from each other. Since he was taught the same as me he was reindexing the ring gaps before reinstalling the pistons. I probably would have done the same thing.

Merle

[HanksB3B]

John,

Tell me it's not the beautiful, fantastic "Crate-Motor" featured in this thread that blew up on you.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=17954&highlight=crate+engine

Didn't know you are working in the field of architecture. It's real tough out there so it doesn't suprise me you are working on a bunch of small projects. I'm a Revit Architecture person.

Hank

Yeah I checked the manual and nothing there too. This might be one of those topics where many opions abound but there's only one elusive correct answer.

Job is going good. I can walk to work and walk to everything else I need, except Napa Auto Parts, which is in the next town north about 3 miles from here. We're busy with all sorts of small projects which is rare for architects and everyone else in the building industry these days, but I'm hoping I can be held onto for at least a year which will help.

[Dave72dt]

I tend to install rings with the oil ring lined up with the wrist pin. Pistons rock a little in the bore and I figure the wrist pin has the least amount of rock so I place the oil ring gaps there. The others I space equi disdance around the piston figuring the ring tension and the rock will make them walk in opposite directions, if at all. Just my theory. Most of the directions that come with ring sets will tell you to space them.

[John-T-53]

It sounds like the best stagger would be 180 degrees apart. I'm going to try that one and if the gaps move a bit, they'll at least have more distance to travel around the piston circumference to line up.

Hank - yeah, this is the one...but fortunately I caught it just in time before it really did blow up! It's in pieces but the pieces are intact.

[HanksB3B]

but what brand of silver paint did you use. I need to get mine looking like it just came out of the crate too. Did you have to remove your engine or is it being rebuilt while still in the truck?

Thanks,

Hank