New piston ring question

[invader_star]

Hey guys. I'm installing some new piston rings in a B3 engine block from an '89 L, and I had a few beginner questions about what to expect. I'm using the original pistons, and I had the block's cylinder's honed. I purchased a piston ring set from autozone, and the brand is Sealed Power. I measured the gaps of the first and second compression rings, I got about .018". The manual says the max is .012", but my block has 190k on it, with freshly honed cylinders. I reasoned that this would be mostly acceptable, since I trust the fellow who did the machining, and I just put on all new rings. Should I be alright?

From what the Ford repair manual told me, I came up with this gap diagram:

I dunked the pistons in motor oil, oiled the cylinders, and they fit pretty dang snug. Sliding them down to meet the crank was kind of hard, but not horribly impossible. I installed all four pistons the same way, and they all felt very snug. I can turn the crank from the sprocket with a ratchet, but there is resistance. To make one full rotation, it takes about 15-18 ft-lbs of force (which isn't that forceful by my feel) when the pistons are in the middle of the cylinders.

How am I doing? Google searching just made me worry more, lol

[FestYboy]

that gap is perfect for turboing your engine, but loose for an N/A build. i would have gotten a set of rings for a .010" piston and then filed to fit.

[invader_star]

that gap is perfect for turboing your engine, but loose for an N/A build. i would have gotten a set of rings for a .010" piston and then filed to fit.

I wish I could turbo this thing, I'm doing all of this work for a B3AST haha. It's kind of nice learning on something that is so small, though. I love these cars though, so I don't mind

I'm not really in a position to get new rings.. how loose am I really?

[blkfordsedan]

Depends on what you're goal is. Are you looking for a "like-new" motor that will run for 100K and not burn any oil, or just a motor that runs good and gets you around? Did the machine shop measure the bores & pistons and tell you what the cylinder wall clearance will be? Were the pistons scuffed? were the ring lands tight?

[sc72]

When you put the rings on the pistons, did you notice the compression rings have a ID mark "dimple" thats to help you put the rings on correctly, '' dimple side up" if the rings are upside down, the compression will be greatly decreased, it will act like it is worn out. Keep the pictures coming, Good luck with the rebuild.

[invader_star]

The main goal is to get it back to a factory-like state. This rebuild is for my girlfriend, so I want it to be reliable and run for years to come. She will be giving it routine maintenance, I'll be sure of that I took in the bare bones engine block to the shop, and asked for a 'cylinder hone' and that was about it. My inquiry was pretty generic, since I didn't know about specifics then. The pistons had vertical wear lines on the elongated edges of the piston head, but that was about it. Do you mean tight landings while the piston is in the cylinder?

[blkfordsedan]

Usually they will measure the bores to determine wear. Then measure the pistons and calculate the piston-to-wall clearance. If its too lose, they will be noisy at start-up and have poor ring seal. The ring grooves also wear and allow the rings to be sloppy in the piston. If the motor had 190K miles chances are a simple hone and new rings will not provide long-term life. At this point, I would just assemble it and see what you got. It could be just fine for a long time. Impossible to tell without measuring everything.

[invader_star]

Thanks sc72, give your festy a hug from 'Blue Steal'

blkfordsedan, I see what you mean. What I'm doing almost seems like a bandaid.. I feel like I would almost have to get rings made-to-fit for my specific pistons in order to get back to factory-fresh. Hopefully my .018" isn't so horribly out of spec... they do feel really snug, I can't imagine what correctly sized everything would be like haha.
Dem new rings

Piston wear:

They all look about the same.


I'll just continue forward. Hopefully some extra TLC will fill the gaps <3

[Dragonhealer]

Hi Invader, The pistons look good! but that .018 gap likely meens the
pistons will be loose in the bore. FestYboy's sugestion is the way to
get proper gap on a loose bore. The most modern method of ring
gap stager is to alternate all gaps 180deg along the 1:30/7:30 o'clock,
oil control too, except the expander, to be 90deg.
If the budget is too tight to deal with issues as you build, at least
you are on the learning curve. Don't worry, it will run fine and be much
easier to do next time!

[Festy46]

When you measured the ring gap, did you use the piston to push the ring down in the cylinder? If you just put it in with your fingers and "eyeballed" it for squareness, you may not have gotten a good measurement. Also did you measure the gap at different depths in the cylinder? The cylinder may be worn more at one place than another.

[invader_star]

Thanks dragon This is encouraging! Going into this, I had far too many questions to feel good about my work. I don't want to do this for 'nothing' haha. Is this diagram accurate to your description?

My only question is that, in the Ford repair manual it says that the oil scrape ring needs to be on a solid portion of the groove. I think 5:30 is right on the edge of the opening, so I'm not sure.
Is this more accurate?

With the oil scrape at 6 o'clock, it is right in the center of the solid groove portion. Conversely, with the gaps at 3 and 9 o'clock, when the piston is installed in the block the gaps are in a vertical line.

Am I on the right track?

festy46, when I measured the ring gap I used the piston head to slide it down a few inches and then took my measurement. It should be accurate, however I only measured the one position. I'll look into that

[blkfordsedan]

I usually measure ring gap with the ring at the bottom of the cylinder, approx at the lowest point of It's travel. The main issue is not having enough gap, so when they expand the ends don't touch. You can use the feeler guages to measure the ring land clearance in the pistons as well. If the ringlands are wore, the rings will flutter or wobble. I think you'll be fine. Some of the best race engines I've had were somewhat "loose".

[invader_star]

I will be continuing forward with this ring gap pattern:


My only concern is that the oil ring rail ring gaps are in the middle of the groove openings, but I think it's okay. Thanks for the guidance everyone