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Help Me Further Understand Top End Engine Wear


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I made good progress today inspecting engine wear. Main and rod bearings all show .00175" to 0.002" bearing clearance.  I confirmed that I have some valve sealing issues. The mess I found inside the block was shocking. All the expansion plugs are out. I dug around a bit, excavating crap from as as far back the 50's I figure. I don't have a ridge reamer yet. I was waiting to see how the bottom end looked.  I'll proceed to cut the ridge off and pull the pistons out the top. I am interested in what I'll find with the rings.

 

Next projects include valve guide wear measurements. Mainly for my personal development. I have a dozen valve guides here ready to go. They will be all installed at some point.

 

The crank looks great.  Bearings have had too much soot going through them for some time. They don't appear worn out, however I will install all new. The block passages are such a mess I figure I might as well take it in to the machinist for chemical boil and cleaning.  3 7/16"  bore is very favourable. I am leaning towards that route.

 

 

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Edited by keithb7
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I made good progress today inspecting engine wear. Main and rod bearings all show .00175" to 0.002" bearing clearance.  I confirmed that I have some valve sealing issues. The mess I found inside the b

Sometimes it’s best to let sleeping dogs lie. However, you have woken the dog and looks like some work ahead.    Many years ago and lots of miles ago, I had a miss in my ‘53 Plymouth engine. It

Pull the pistons...check out those rings. I think it sat for a long time in a damp environment. Upper rings aren't sealing/working very well at all.

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I'm just now coming in on this thread.  It's been some great reading, and I wish you the best of luck with it all.

 

One thing I'd like mention is you should exercise extreme caution when using a ridge reamer.  I used a ridge reamer on both flathead sixes that I've rebuilt, and both machine shops (different shops, 15 years apart) told me, after I had already done it, that they advise their customers not to use them.  They don't even use them themselves.  They recommend just pounding the pistons out the top of the block.  Of course, that breaks the rings and ring lands, making it much harder to ascertain the condition of the engine up to that point. 

 

Apparently, it's very common for the reamer to cut too deeply (radially into the cylinder wall) and too far down the length into the cylinder, which makes it impossible to reuse the cylinder without boring oversize, and it often makes it impossible to bore to the next oversize, instead requiring it to be bored one or two sizes beyond that.  I guess I got lucky with my first rebuild, because the machinist was able to take it from the 0.040" oversize that I discovered to 0.060". During my second rebuild, I thought I took great care, but the machinist said I had removed too much material to go from the standard bore size (my engine had never been rebuilt) to 0.020", instead having to up to 0.030".

 

My only point with this is that if you still have any desire to just re-ring your engine and not bore it oversize, you need to be extremely careful when using a ridge reamer.

 

Speaking of re-ringing, as you mentioned already, I think there is some risk that the existing ridges might not play well with new rings, not quite conforming to each other, and possibly causing impact of the rings against the ridges and breakage of rings and piston ring lands.  So this is a nudge in the direction of boring oversize.  And if you follow through with a 1/16" overbore, as you've discussed, then digging too deep with the ridge reamer is less of a concern, although I'm sure someone could cause enough damage to risk ruining the possibility of using even that large an overbore, if they really got carried away.

 

Anyway, good luck!

 

Matt

Edited by Matt Wilson
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Thanks for advice Matt. Perhaps I should try removing the caps, cover the con-rod bolts threads. Then push all piston all to TDC. Lift my crank out. Then bring everything out the bottom. Is that possible? 
 

If you are interested in following along I am uploading videos of my progress to my You Tube channel.  Seek out my name “Keith Barron”. You’ll find my videos. 

Edited by keithb7
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Pistons cannot be pushed out the bottom....they hit the main webbing.

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I've torn down a lot of engines,  Very few have a ridge deep enough to really lock up on the rings.  I think that's because the top edge of the rings are not really square any more due to touching that ridge when running.  And they no longer have a lot of tension due to wear.  Bottom line, I don't ever remember breaking a ring or land when taking them out.  But, I never really wallop them when removing.  Usually a hammer handle is used to push them up until they touch the ridge, then a tap with a dead blow hammer, softer face absorbs a lot of the shock, gets them out.

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Keith, there's probably a number of fellas here that have used a ridge reamer and made it work, and some that have screwed up when using it; they might not have chimed in yet.  I agree with Matt Wilson though.  Please don't use it and risk making a mistake you can't undo.  I haven't used a ridge reamer on an engine, but I know how they work.  As a machinist, it's something I'd call a "hack" tool.  There's no way that thing is square, and no way you're going to know exactly how much material you're going to remove.  In addition, it's really not even a reamer, it's an adjustable bore bar at best.  I've reamed and bored thousands of holes on manual mills and lathes, and on the (3) $500,000 each dual spindle dual turret Nakamura CNC lathes I operate at work every day.  I've used adjustable bore bars (and true adjustable reamers), and this reamer that's being discussed here is something I would never consider using on a good engine.  Please don't use it.  

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Well I guess I’ll try pushing the pistons out with the ridge still there. Carefully, and see what happens. For my own education I was hoping to learn why rust is present on the top of my cylinder walls. It appears to me that the rust extends down lower than the top compression ring. There could be a few broken top rings. I may not be able to prove it. If a piston comes out with a broken ring did it break while passing the cylinder ridge? Or in service? I suppose with decent magnification I could study and look for a  ductile or stress type  break on a broken ring.  Perhaps I can tell if its been flopping around in it’s groove for a long time. Or if I just broke as it was forced out of the block? We shall see. 

Edited by keithb7
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4 minutes ago, keithb7 said:

Well I guess I’ll try pushing the pistons out with the ridge still there. Carefully, and see what happens. For my own education I was hoping to learn why rust is present on the top of my cylinder walls. It appears to me that the rust extends down lower than the top compression ring. There could be a few broken top rings. I may not be able to prove it. If a piston comes out with a broken ring did it break while passing the cylinder ridge? Or in service? I suppose with decent magnification I could study and look for a  ductile or stress type  break on a broken ring.  Perhaps I can tell if its been flopping around in it’s groove for a long time. Or if I just broke as it was forced out of the block? We shall see. 

When we took out the pistons from the Meadowbrook engine, 5 of them had broken rings; (several breaks per) not from removing the actual pistons.  Yeah, every engine is different.  I'll think you'll be fine. 😊

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28 minutes ago, keithb7 said:

Well I guess I’ll try pushing the pistons out with the ridge still there. Carefully, and see what happens. For my own education I was hoping to learn why rust is present on the top of my cylinder walls. It appears to me that the rust extends down lower than the top compression ring. There could be a few broken top rings. I may not be able to prove it. If a piston comes out with a broken ring did it break while passing the cylinder ridge? Or in service? I suppose with decent magnification I could study and look for a  ductile or stress type  break on a broken ring.  Perhaps I can tell if its been flopping around in it’s groove for a long time. Or if I just broke as it was forced out of the block? We shall see. 

If you can push them out, and find broken rings, you can be sure that a 'push' didn't break it.  Even using a hammer, carefully, you can limit the force so you can tell.  And, broken rings in a running engine always leave signs, ring groove worn from the pieces flopping up/down, slight score on the wall from the broken ends, second very slight ridge from the next ring down that still had wall tension, etc, etc..  Something will be a telltale.

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Usually you can look down below the top ring land and see broken rings. But usually the broken rings leave a score on the cinder wall where broken.

Carefully using some 600 grit paper you might try sanding just  the  sharp ridge edge off enough to let the rings slip by.

I have removed many flathead pistons without knowingly breaking the rings on the ridge being easy using rod chopsticks and my palm on the end of them pounding them out.

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Keith,

Just finished an in-car overhaul on my '50 Coronet. I don't envy you replacing the valve guides. That was the absolute biggest pain in the *$$ part of the whole process. Guides that have been in a block for 70 years don't seem to want to leave their home. But after a LOT of swearing and finding a Bishman 810 Valve  Guide Remover tool on e-bay, I got 'em out. Had to drill them first, then used a length of stainless 5/16 all-thread to replace the steel bolt on the tool, as the pressure ripped the threads off the steel bolts long before the guide let go. 

Wes

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Agree on the air hammer.  And no special driver is needed.  One can be made from a stock unit quickly if  a lathe is available.  But, IME, there isn't enough room to move the guide down to clear the block with the lifters in place.  The work around is to drive it down part way then break off the part exposed with the air hammer with a chisel in it, then drive the remaining piece down and out.

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I proceeded to remove the valves and camshaft this evening. Pulled out #1 piston too. It easily slid past the top ridge. 

I found a broken top piston ring. Compression ring. I did not break it upon removal. That explains the rust on the top of the cylinder seen in my pics, earlier in this thread. 
 

I’m no expert but the piston looks quite good to me. No carbon build up. I don’t see signs of much wear. However I do need to research and learn where to measure a piston for wear. I attempted to measure #2 compression ring gap. Not much point. The gap seems to be 3/16” or so.  Spec is in the thousands.  You can see my ring near the bottom of the cylinder in the second pic below. 
 

I feel pretty optimistic about what I’m seeing. This engine is not a high mile tired piece of iron. I’m not quite sure I need all the cutting services of a machine shop. A block hot tank boil is definitely happening. 
 

One question. When re-using tappets should I record all positions so they go back in the exact same spots? Tappets and cam look very clean and nice!


 

 


 

 

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Edited by keithb7
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The upper ring land (groove) is most likely worn too wide.

That would require the piston to have the groove cut to install a spacer ring.

This narrow spacer ring was done back in the day to correct worn ring lands. Correcting piston ring side clearance back to spec.

Piston skirt dimensions also need to be checked, pin bore, pin bushings etc.

Most likely new pistons might be in order.

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Thanks Dodge. I’ve had more more time to think this thru. Top ring groove is clean because the broken ring has been bouncing around in there. I stacked feeler gauges in the grooves. Top groove is considerably worn wider than second. About .016 or so wider. 
 

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Well I thoroughly enjoyed the tear down. The easy work! Lol. The real work comes now. 
 

Only #1 piston had a broken ring. No others. 
 

I’ve still got a few more little bits to remove from the block then its off to the machine shop. I’ll wait to order any new parts until the block and crank pass crack testing. 
 

 

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C4FCA46E-7F82-431B-B6C0-48779B5D6A9B.jpeg

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I’m about to remove all the valve guides. I need to be sure that the new ones I install are indexed probably and set at the right depth.  Mopar manuals claim ⅞” from top of block deck to top of valve guide. 
 

I got to thinking about a simple way to achieve that, without buying another tool I’ll probably use but once. 
 

I measured the distance on the bottom side. Inside the valvetrain area. Its 2 ⅛”.  I cut up a wood spacer block. This will be my reference for installing new guides, from the top down. I contact the wood block with the guide end, I stop driving the guide.  
 

I checked, the stock factory installed guides are not all exactly the same depth. Pretty close seemed good enough. This step does not seem to require micro-measuring to spec.

Seen here, my spacker block placed (wedged) between a pair of guide ends and the engine block. Guides are at the bottom of this photo. My wood spacer sits right on the tappet bore deck.  Good enough?

 

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Edited by keithb7
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Well, let's think about this.  Minimum clearance between the guide and the retainer is .060", anything more than that just stuffs more guide into the port.

 

Stock guide length is 2.813".

Stock valve length is 4.845"/4.840" intake and exhaust.

 

Guide to valve length ratio is 58%, very generous.

 

I'd set the guide as low as I could with proper clearance at max lift and remove the portion of the guide that intrudes into the port.  This engines aren't known for being good breathers and having a tree trunk (valve guide) sticking up in the port isn't helping.  there is no sideloading to speak of like in an OHV setup and the lift isn't very much, all factors that should allow for a shorter guide.

 

Looking at your valve guide removal video, looks like you have over an inch of guide in the port.

 

Something to think about.

 

 

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Good news to share.:  My 25" long block was boiled and got a mag-particle check. No cracks! I dropped by the machine shop. Paid the bill and took my block back home.

Now I'll proceed to order all my parts. Also I'll install the new valve guides here at home. Once all the parts arrive, I'll take everything back to the machine shop for boring and a crank grind.  It'll probably take about a month for the parts to show up. Looking around at the mass number of blocks and cranks at the machine shop, I figured it was best to take my block back home until the parts arrive. I cannot have them misplace it! Lol.

 

When I measured the mains and rods with plasti-gauge I noticed an uneven wear. A slight taper from end to end. Normal wear for a crank. I estimate its wearing about .0005 to .0015 out of true. I'll get the cranked turned down .010 and order bearings to match.

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