Cylinder Walls

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70sublime340

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So I have started tearing the motor down to change the rings, attached is a pic of a cylinder wall. Has hatching in areas but is glazed and shiny on the rest of the wall. Also has ALOT of buildup for being an engine with less than 2k miles. However, initially had not breather system and had a carb that would constantly flood the bowls and probably wash the cylinders. Am I spinning my wheels by changing the rings? Or it's this typical of bad rings and can be honed with good results. Also, it's only
Gonna be another year in the car (having a hot 340 built) with weekend cruising. Don't need 50k out of it, just don't want billowing smoke.
 

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that bore is not round, no hone is gonna fix it, needs to be bored.
looks like at least a 100,000 mile cylinder to me.
 
In your pic it looks like there are ghost rings in the bore from detonation .
 
Scotty, that could be. I know the timing and air/fuel mix has been played with from
One extreme to the other thinking the damn thing was running rich. Also it almost looks like water sat in the hole and started pitting (if you notice the crescent shape dead center of the bore). However nothing catches my nail at all. It's nice and smooth. I'm interested to see the passenger bank. I will try to pull that head tomorrow and get pics of more cylinders. I'm hoping I can put a band aid on it to get by til the 340 is finished
 
Measure for sure.

FYI, since you want to limp this along, when I was a poor student, I re-ringed and engine that was out-of round and tapered on all bores; taper was .008"-.010" on a couple! A hone job and ring spacers was all I could afford. It didn't run evenly but it did fire on all cylinders, and did not billow smoke. It was an old low compression 292 truck engine so if this is a high compression engine and you are going to lean on it, your results may not be so good. Anymore, I just don't bother without a proper bore job.

A PCV will certainly help.
 
I kinda think the bore is more too big,, than outta round,, letting the piston "rock" causing the shiny spots,, and I don't like anything about that cylinder..

BUT I'm with nm9,, in that the motor could be patched up to run for a while,,

In situations where the bore was marginally oversize,, it was not uncommon to "knurl" a piston skirt (see pix),, expanding the metal on the skirt, and minimizing the piston "rock,, helps keep the piston square in a worn out bore..

If you can find someone who still does "knurling",, do it to all the pistons nec (prob all),, deglaze,, cast rings,, should be good for a while..

I'd be intertested how much piston/wall clearance there is..

Take all the rings off a piston,, put a .006 - .008 feeler guage alongside the piston,, and slide the feeler/piston upside down into the bore,, gently see how far it'll push down the bore without jamming the piston...

hope it helps
 

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70sublime340 said:
So I have started tearing the motor down to change the rings, attached is a pic of a cylinder wall. Has hatching in areas but is glazed and shiny on the rest of the wall. Also has ALOT of buildup for being an engine with less than 2k miles. However, initially had not breather system and had a carb that would constantly flood the bowls and probably wash the cylinders. Am I spinning my wheels by changing the rings? Or it's this typical of bad rings and can be honed with good results. Also, it's only
Gonna be another year in the car (having a hot 340 built) with weekend cruising. Don't need 50k out of it, just don't want billowing smoke.
Click to expand...

I Take It, That You're Looking For A 'Temporary' Quick-Fix

It can be done. The Cylinders {though most likely out-of-round} can be
'Flash-Honed" to create a seating finish for 'soft' Oil-Rings.

Next step, get a set of 'Sealed-Power' Quick-Seating Cast Iron Rings {+.005"}
over-size.

It will work.
 
The reason the bores look like that is most likely due to the bores being honed without a torque plate. If you make them round without a torque plate, I guarantee that once you bolt the heads on, the bores will be distorted.

From the photo it doesn't look that bad, though. Dingle ball hone it, put some cast iron rings in it and run it. Do not run moly rings on a re-ring! But make sure that you get all of the grit out of it from the honing process and also make sure the the ring lands aren't all beat up. If the ring side clearance is too big, the rings will act like oil pumps, pushing the oil up into the chamber.

Regarding knurling the skirts - don't waste your time. By the time the rings are seated, the knurling will be worn down to nothing.

I was a machinist for ten years and I did all of the block boring and honing in our shop. BTDT.

My friend ran cylinders that were tapered .008" in his drag car way back when. It was a 383 and it ran 12.80s with a re-ring on those .008" tapered bores.
 
lilcuda said:
Regarding knurling the skirts - don't waste your time. By the time the rings are seated, the knurling will be worn down to nothing.

I was a machinist for ten years and I did all of the block boring and honing in our shop. BTDT.
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Ten years obviously wasn't long enuff,,

Those pistons were knurled over 20 yrs ago,, and have over 20,000 miles on them,, and as you can see by the measurements,, the knurled section is clearly .005 - .006 wider than the un-knurled section,, I measure several pistons, at several places,, same result..

cheers..
 

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inertia said:
Ten years obviously wasn't long enuff,,

Those pistons were knurled over 20 yrs ago,, and have over 20,000 miles on them,, and as you can see by the measurements,, the knurled section is clearly .005 - .006 wider than the un-knurled section,, I measure several pistons, at several places,, same result..

cheers..
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Calipers aren't accurate enough for measuring engine parts unless you are looking for an approximation. You wouldn't use calipers to measure pistons for boring a block. If you would, then you shouldn't be working on engines.
 
lilcuda said:
Calipers aren't accurate enough for measuring engine parts unless you are looking for an approximation. You wouldn't use calipers to measure pistons for boring a block. If you would, then you shouldn't be working on engines.
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LOL ,, you're funny..

I shoulda said approx 5 - 6 thou. on several pistons,, pix speak for themselves.

I've used these same calipers to set pinion depth to a thou,, and it measures "marked" shims perfectly..

No,, it's not a mic.. but the difference is clear..

Whatcha gonna say when I show pix with a mic,, better start thinking now...
 
inertia said:
LOL ,, you're funny..

I shoulda said approx 5 - 6 thou. on several pistons,, pix speak for themselves.

I've used these same calipers to set pinion depth to a thou,, and it measures "marked" shims perfectly..

No,, it's not a mic.. but the difference is clear..

Whatcha gonna say when I show pix with a mic,, better start thinking now...
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Yep. You win. You're smarter than me. I guess that's why you use all those extra commas and periods... ,,, ... ,,,

I'm out.
 
When I was younger, ingnorant, and too poor to care... (not judging, just stating my time of life...lol) If it was a decent running engine, I would stick rings in it and leave the bearings and go. They'd run ok for a few thousand miles that way. Get some file-to-fit iron faced rings, and I wouldn;t use a dingle ball - I'd just use a green scotchbrite wrapped around a flex hone. Use WD40 for lubricant. You'll give it some finish to seat, but it won't take hundreds of miles to get there. If it ran, it will run again. if it smoked and the rings were the reason, it should get better. For a time.
 
lilcuda said:
Do not run moly rings on a re-ring! But make sure that you get all of the grit out of it from the honing process and also make sure the the ring lands aren't all beat up.
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I am curious as to why not.... I always have used moly tops with good results. Anyone know?
 
lilcuda said:
Yep. You win. You're smarter than me. I guess that's why you use all those extra commas and periods... ,,, ... ,,,

I'm out.
Click to expand...

I'm not trying to be "smarter",

I'm correcting your totally B.S. statement that knurling is a "waste" and dissappears in a few miles, which may cause people to disregard something that could save some $$$, and/or help solve the problem being faced here..

I find it curious that you don't know a vernier caliper is capable of measuring a few thou diff in diameters, and suggest only a micrometer can do that,

That may cause some folks to question your credibility..

And my punctuation,,, REALLY,,, how old are you..??

cheers..............
 
nm9stheham said:
I am curious as to why not.... I always have used moly tops with good results. Anyone know?
Click to expand...
Chrome moly rings need a real round bore and good hone, nice cross hatch, to seat. Iron are a lot more forgiving, will seat easy.
 
Piston Knurling

Old-school Machine Shop trick. Popular in the late-1950's and 1960's.

The Piston Knurling Device massaged the metal outward, and helped
create an {approximately +.005"} over-sized Piston.

Also, the grooves knurled into the Piston-skirt helped retain some oil for improved lubrication.

An application designed to perform on used and worn 'Cast Pistons' to help extend
the life of the Piston on low-cost engine rebuilds.

But, this machining-technique was applied more for 'stock-type' applications and
not high-revving 'performance-oriented' Engines.


Measuring Piston Diameter

A Micrometer is the only way to go when measuring a round or circular object.
 
Didn't know that about iron vs. Molly rings for a re-ring. Good thing I'm reading this before I freshen up my 318.
 
Ring types are being confused.
1. Iron faced : are std iron rings. Stock, plain jane. Can be ordered .005" larger to be filed-to-fit. Need a fairly rough surface finish and will take some time/mileage for the rings to seat to the walls.
2. Moly faced : std iron rings, with a Molybdenum based coating applied in various forms to the face of the top ring. Also called "moly rings". usually found in performance ring sets, available in pretty much any size/style. The typical ring used today in everything race. Needs a smooth to very smooth surface finish. The moly coating is used to speed the compression ring seating to the wall. They typically are seated before the came is broken in if the finish is right. If the surface finish is too rough, the moly coating is rubbed off immediately, and the rings become std iron faced, and require the same mileage to seat. (fairly common issue)
3. Chrome faced: std iron ring with a chrome plating on the compression ring. This provides a very long service life and resistance to dirt and abrasion. I'm not sure what finish they use - I've never run them. But it's different than the std iron or moly rings. They take some time to seat but last a very, very long time in harsh environments like industrial and desert/dirt.

Chrome-moly is an alloy that is used for structural tubing and such. It's not a ring material.
They all require a straight round bore to seal, and some sort of crosshatching to seat and last. Although the crosshatch and Ra vary for each type...
 
Thanks Moper.... I was about to say that chrome-moly is a new term for rings for me! Moly rings are iron rings with some degree of moly facing on them; a lot that I see now seem to be a thin moly facing on an iron ring. I have seen some in the past that appeared to have a slot in the iron ring surface filled with a light colored moly material. But either way, they are basically an iron ring with a special top ring treatment.

Chrome rings facings are quite different as said, and take care to seat. Not attractive for a re-ring job. I use moly rings on everything for the ease of seating, and would not hesitate to use them on a re-ring.

BTW, the Hastings recommended surface finishes for iron vs moly are not all that different.
I need some more punctuation marks ........How ,,,,,,,,,,about///////////this::::::LOL;;;;;;;;;
 
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