Fresh rebuild-broken rings?

[SpringHeeledJack_53]

Good morning all, I've been digging around in here for awhile and decided to make my first post. I'll start with a brief history of the car to lead into my problem/question.

I bought this 53 Plymouth about 3 years ago when I was in Pittsburgh and drove it everyday, sun rain or snow. No problems for over a year until I moved back to Texas. I drove it for another 2 years daily about 60 miles round trip in rush hour with only some minor repairs along the way. I decided to do a complete engine over-haul while the money was available. Noticed all the top compression rings were broken and one piston cracked (Ran good at 70 mph). Got her all buttoned up after a few months and yet again my luck ran out. I never could get it to idle smooth, has a miss here and there. Changed points, cap, rotor, blah blah. Still there. Last Saturday coming home from work cruising around 70 mph, an expansion plug popped out and dumped all the coolant. I was able to shut her down before getting too hot But once at a stand still it peaked about 240°+. New plug and coolant I was able to get it home. Popped the top to investigate any internal damage and noticed on #'s 3 and 4 some light scoring on the valve side of the walls.

When I tore it down the first time it had the same issue in the same locations. I'm sure I am answering my own question, but that is the cause of broken rings right? Would these be my most likely cause for the misfire? Are the broken rings caused by my installation or the high heat? Can I run it as I did before the rebuild? I can't put much into it at this point. But I would hate to waste a rebuild.

I apologize for the story. thanks again! I'd post a photo but not sure how...

[Plymouthy Adams]

broken rings are usually a sign of two things..improper technique slipping piston assembly into the bore...improper removal of the cylinder ridge wear on rebuild..

[greg g]

Consider that you have a long stroke motor.  at 70 it is probably running near 3600 RPM. That is where the factory pulled peak HP for these engines.  Extended running a HP peak is probably OK for a new engine, but for a 60+ years old one even rebuilt that running her hard.  How is your timing, and what doe your plugs look like?  You may be getting some preignition especially with today,s gas and your Texas temps. that can also be bad for top rings. You may have some crank flex, or even some vertical movement of the shaft within the bearings.  Even a couple of thousandths  at high rpm can be banging the rings into the cylinder ridge.  But I think pre ignition might be the culprit here. 

 

As long as you have it pulled down, check the ridge and make sure its gone or very minimal. I assume you are going to hone the cylinders during the repair process.  Make sure you check your ring end gap and make sure yoru gaps are staggered around the pistons. Use a good pre lube when reassembling and assure the rings are properly compressed when popping then back in the bores. 

[Don Coatney]

Did you check for proper ring end gap as part of the assembly? Are the piston rods assembled with the squirt hole pointing towards the cam shaft? Broken piston top ring and subsequent broken piston as pictured is common on high mileage engines and engines that have experienced excessive heat.

 

 

[Dave72dt]

Was this engine bored oversize during the overhaul?   I ask because I've found definitions of " overhaul" vary and some of the causes for what you are seeing differ for a fresh rebore  compared to honing and rering the old bore.

[SpringHeeledJack_53]

Thank you for all the replies!

And this is a complete over haul. The block crank and head were sent to Blain's in Dallas. They were std bore but had to go to .060 due to out of round and gouges. Every thing but the crank, cam and rods were replaced. The ring end gap was checked.

Greg, as far as I can tell the timing is near spot on. I do not have a timing light so I play it by ear and feel. But it is something I'll have to investigate next.

Don, I am 97% sure the holes are facing the cam side...which brought something to mind...if I remember correctly the pistons I first pulled had two slots on the skirts While the new ones had it only on one side. Now if this is true and I installed them with the slot on the cam side, was I right? I'll have to dig the old ones out of the scrap bin tomorrow.

Dave, yes. It was bored over size and I will be rehoning.

[Dave72dt]

Those score marks can come from the ends of the rings. They have  sharp corners on them which can dig in a bit and leave those marks.  Also if the rings are gapped filing in the wrong direction, that will also leave a little shard on the end that will do the same thing.  The other scoring can come from overheating and too close of piston cylinder tolerances.  As long as you're pulling it apart for honing, take a real close look at the skirts on those two pistons.

[SpringHeeledJack_53]

[SpringHeeledJack_53]

I'm not sure why they have rotated, this is after the rebuild, and one of the scratched cylinder walls

[Dodgeb4ya]

Slots in the piston (factory) are opposite of the con rod oil metering hole which face the cam.

[greg g]

Picture one above suggests the rings may have been installed upside down.  

[Ricky Luke]

Picture one above suggests the rings may have been installed upside down.  

It's an Australian car... looks fine to me

 

Rick

Edited April 22, 2015 by Ricky Luke

[SpringHeeledJack_53]

I have already put the head back on with a new gasket because I live in an apartment and car repairs are frowned upon in the parking lot. Its not impossible to do this in the parking lot but I'd prefer to do it in comfort at work which is about 19 miles away. Would I be risking much damage to drive it that far? Or is this something I should do where it sits? Abother $35 head gasket wouldn't hurt my feelings as much as more machining or something.

By the way, this is my FIRST flathead rebuild (a bit different than my usual V8 and V10s here at work) and everything I've learned and done has been from repair manuals and sites like this. I'm thinking there maybe a few things I overlooked during this rebuild haha.

[Niel Hoback]

Your air cleaner is too small. Needs more area for more air flow.

[jeffsunzeri]

You can certainly drive the car 19 miles to start the rebuild. It's going to need one with that scoring in the cylinder.

 

Are all the cylinders scored like that? The slight discoloration at the edge of the piston may indicate pre-ignition and/or overheating.

 

Although the engine will run in that condition, and it may actually be smooth and seem ok, that condition will cause overheating and rapid wear as well as oil breakdown due to blow-by. The faster you run the engine, the faster it will wear and break, overheat, or seize.

 

The scoring can be a result of bad air filtration, oil breakdown and dirt in the oil, or poor/incorrect piston and rod installation orientation.

 

The sad news is that now that its .060 over, you may be at the end of that blocks useful life. Some blocks can take an .080 overbore without sleeving, and others won't. It's hard to tell from a picture, but it seems like those scores won't hone out and another bore or another block is in your future.

Edited April 22, 2015 by jeffsunzeri

[greg g]

another thought, you mentioned a rough idle. Did you check for air leaks after the carburetor?  Air leaks between the intake manifold and the block can cause the cylinder pair to lean out.  A lean mix will cause a rough idle and worse a lean mixture will be more prone to pre- ignition,and hotter combustion chamber temps.  Did you ever put a vacuum gauge on when you were chasing the rough idle?  When you get it back together I would check the gaskets from the carb base to the intake ports and assure you don't have any vacuum leaks.  especially in the area of the effected cylinders.  And certainly if you are planning for extended runs at 60 to 70 on the highway.

[Young Ed]

I don't think you'll need to redo the bore just from that. Dad and I had one with rust pits in one cylinder that we put new rings in and it ran fine. Smoked a little though I don't think yours is nearly as bad.

[SpringHeeledJack_53]

What would cause the freeze plug to pop out? They were installed when the machine work was done. Wrong rad cap perhaps?

[Plymouthy Adams]

not properly seated and dimpled.....

[SpringHeeledJack_53]

I have a air guide mile minder vac gauge on the column and an old one I use under the hood. I usually get a reading around 16-18. The air guide is a bit jumpy especially while driving and on bumps (too sensitive I guess) and the other one I use stays steady. I've checked for leaks over and over and found nothing. I'll go back over it after I install new rings.

[SpringHeeledJack_53]

After getting everything back together to drive to work, all I am getting is really loud back fire from what sounds like one or two cylinders . Brought #1 to TDC, pulled the cap and noticed that the rotor was in the #6 position. I haven't touched the distributor at all Since a first set the timing weeks aago. Pulled it and rotated it back to #1. Turned the key and now it sounds like a miss fire on each cylinder. Scratched my head a few seconds and thought...maybe I have the wires at the cap wrong.. moved them around. Turned the key and now only the solenoid pops. Checked all my wires, battery is showing voltage...any ideas?

[55 Fargo]

After getting everything back together to drive to work, all I am getting is really loud back fire from what sounds like one or two cylinders . Brought #1 to TDC, pulled the cap and noticed that the rotor was in the #6 position. I haven't touched the distributor at all Since a first set the timing weeks aago. Pulled it and rotated it back to #1. Turned the key and now it sounds like a miss fire on each cylinder. Scratched my head a few seconds and thought...maybe I have the wires at the cap wrong.. moved them around. Turned the key and now only the solenoid pops. Checked all my wires, battery is showing voltage...any ideas?

How about any of the plug wires on the wrong cyl, just 2 out of place can make it run the $hits.

I did this not that long ago, had 2 wires on the wrong spark plugs and it ran terrible, but it ran.

[SpringHeeledJack_53]

I double checked and they all seem to be in the proper place. I figured it would at least start but it only pops each time it fires. I did pull off the air cleaner and look in to the carb. It had a bit of fuel in the intake. Seems the throttle link was stuck open slightly. But I've been told flooding wouldn't cause back fire or 'popping'.

I've never had this problem with one of these before. I am stumped.