Reflecting cylinder walls

[DRG-ler]

Hi folks...

yesterday I took off my cylinder head because the head gasket was burned... Of course I broke off the base of the ignition distributor...

Ordered some new parts today and looked at the engine again and found that the cylinder walls are almost mirror clean!!!






The engine ran well. A pressure loss test beforehand also showed a loss of only 25% on all cylinders. (In the middle of the green area of the display.) However, I don't really like the bare cylinder wall. Can anyone tell how I should deal with this problem? I'd like to hone over it, but I don't want to pull the pistons. I have concerns with the connecting rod bearings made of white metal.

What would you do?

Does anyone have the material composition of the liners?

MFG Andy

[frank55a]

Originally Posted by DRG-ler

I have concerns with the connecting rod bearings made of white metal.

Not sure what you are referring to "rod bearings made of white metal". I have never heard of babbitt being called "white metal" although I have heard pot metal referred to as white metal. I don't think your bearings are "pot metal", if they were I think they would have been shot only after a few miles. The bearings should be made of babbitt. Babbitt has been used for bearing material since the beginning of the auto industry. The old engines generally prior to WW2 the bearings were pored babbitt while it is my understanding that the more modern engines have inserts made of babbitt. My engine rebuilder uses aircraft babbitt, it is reported to be the best available.

As long as you keep track of the which piston comes out of which cylinder and ensure the shims stay in place you should not have a problem pulling the pistons. This also gives you a chance to check the clearance of the rod bearings and if need be to tighten up the clearances. This would also be a good time to check your main bearing clearances and tighten them up as well, if need be.

[john in illinois]

If it was mine and it ran well and had good compression,I would not disturb it.

John

[Synchro909]

Originally Posted by frank55a

Not sure what you are referring to "rod bearings made of white metal". I have never heard of babbitt being called "white metal" although I have heard pot metal referred to as white metal. I don't think your bearings are "pot metal", if they were I think they would have been shot only after a few miles. The bearings should be made of babbitt. Babbitt has been used for bearing material since the beginning of the auto industry. The old engines generally prior to WW2 the bearings were pored babbitt while it is my understanding that the more modern engines have inserts made of babbitt. My engine rebuilder uses aircraft babbitt, it is reported to be the best available.

As long as you keep track of the which piston comes out of which cylinder and ensure the shims stay in place you should not have a problem pulling the pistons. This also gives you a chance to check the clearance of the rod bearings and if need be to tighten up the clearances. This would also be a good time to check your main bearing clearances and tighten them up as well, if need be.

I have only ever heard the bearing metal referred to as Babbitt in the US. Everywhere else, it has been called white metal.
I firmly believe in "if it aint broke, don't fix it" so the advice to just put things back together is sound, IMO. If you really want to do something, you could give the bores a quick lick with a hone - just to break the gloss on the surface, then fit a set of new rings. This would be a good time to check the clearances in your bearings. It can all be done with the engine in the car.

[Russ/40]

It only needs a new head gasket. Why are you trying to find trouble? Replace the gasket and drive to your heart's content.

[Ruth]

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Originally Posted by Synchro909

I have only ever heard the bearing metal referred to as Babbitt in the US. Everywhere else, it has been called white metal.

Learnt something new today. Thanks Synchro.

[nkaminar]

The cylinders look great with the exception of a little bit of corrosion on #2. Cast iron has a unique property in that it takes on a mirror shine after being broken in. The graphite and iron produce the shine. You only need to hone the cylinders if you are going to put new rings in and only because it helps the rings to seat.

Run the pistons up near the top of the cylinder and then try to move the pistons front to back and side to side. There should be no perceptible movement or only a very tiny amount. If you get a large movement then the cylinders and/or pistons are worn.

Put some light oil like 3-in-one or sewing machine oil on top of the pistons and watch to see if it leaks down past the rings. You only need a small amount. It is leaks down within an hour or two then you may need new rings, and if new rings then you need to hone the cylinders. In the old days it was typical to replace the rings and lap the valves frequently and maybe take up the bearings at the same time. It was sort of a maintenance thing. If the engine was making blue smoke and had a lot of blowby then that would also indicate new rings are needed.

[rotorwrench]

If the cylinders don't have much overbore, Id look for the classification of copper sandwich type gasket that has the appropriate width for the size of the bore. Some companies make all their gaskets to fit large overbores and that makes for a more narrow section of gasket between 1 & 2 and 3 & 4 so as not to interfere with larger piston sizes.

This is a good guide.
https://www.fordgarage.com/pages/ABc...asketguide.htm

[PC/SR]

Nothing wrong with the cylinder walls. They wear in and are shiney. Do not know what you mean by 25% loss of cylinder pressure, what is the actual reading? But, if you want to replace the rings while you are at it, just hone the walls unless you have a substantial ridge at the top. Then get a ridge reamer. Used to be able to rent them at rental shops. You can get a stone hone at Napa for home use which is fine for stock use. No need to get a machinist to do it for a basic ring job. As noted, used to be just normal maintainance. Do not worry about the babbitt. The carbon on the pistons is not excessive so I would say your rings and valves are fine. Sounds to me like you have basically good engine,.

[jeepguy1948]

I completely agree with the gentlemen that say that you are working pretty hard to find problems where problems don't exist. Those cylinder walls look great only if there was scoring present (which there is not) would there be cause for concern. Also concerning would be a heavy ridge at the top of the bore that would indicate excessive wear (again there is not any at all). Another area of concern would be heavy carbon build up (again there is hardly any carbon at all). You made no mention of an engine knock so the rod bearings are probably fine too. I may not be the sharpest tool in the shed but that motor looks pretty fresh to me (like only one or two thousand miles fresh). With todays better oils, and the fact that you aren't driving on dirt roads without an air filter, and the better fuels available today, and I doubt that this is your daily driver either. My humble opinion is that if you put a good head gasket on it as suggested above, with proper sealant, replace the the head bolts (studs) and put some sealant on the bottom end where it goes into the block (Teflon tape works fine, or almost any kind of pipe joint compound is fine), studs only finger tight into the block, torque the head stud nuts several times through multiple heat cycles, that motor will probably serve you well for the rest of your life. Just my $0.02.

[jack backer]

Model A pistons have wide rings that tend to shine the cylinder wall. And don’t seal as well as modern thin ring pistons.. that being said, it also reduces cylinder wear, which is a good thing. Your combustion chambers should be darker, your running a little lean, check manifold for vacuum leak.

[Bob Bidonde]

The cylinder walls look normal. Use them as is.

[Benson]

Suggestion:


Do not use a wire wheel to clean off carbon.


Small pieces of wire brush break off and get stuck between pistons and cylinder walls.



Then you WILL need to bore and replace pistons because of the vertical grooves worn in the cylinder walls.

[TerryO]

If it's not broken, fix it until it is broken...
I know a couple of guys who like to do that...


TOB

[BRENT in 10-uh-C]

Originally Posted by DRG-ler

Hi folks...

yesterday I took off my cylinder head because the head gasket was burned... Of course I broke off the base of the ignition distributor...

Ordered some new parts today and looked at the engine again and found that the cylinder walls are almost mirror clean!!!

The engine ran well. A pressure loss test beforehand also showed a loss of only 25% on all cylinders. (In the middle of the green area of the display.) However, I don't really like the bare cylinder wall. Can anyone tell how I should deal with this problem? I'd like to hone over it, but I don't want to pull the pistons. I have concerns with the connecting rod bearings made of white metal.

Andy, the answers here can often be all over the place. To begin with, you are correct that "white metal" is the proper name for Babbitt, ...since Babbitt is actually a brand name after the inventor. White Metal alloy is the composition of Tin, Copper, and Antimony and is the proper name that should be used.

What I am unclear of is if the head gasket was burned, I would assume you had either a combustion leak -or a water leak? If it was a combustion leak, is that the area I am seeing between #3 and #4 cylinder? If so, why were all the leakage readings the same? Why were the cylinder leakage numbers of the affected cylinders not different??

To further my thoughts, if you indeed performed a 'Pressure Loss' test (a/k/a Cylinder Leak-down test) properly, your readings of 25% are excessive IMO. Generally speaking, in performance applications where the rings are seated, a reading of less than 5% is desirable with 10% about the maximum leakage most consider acceptable. In modern engines using a moly ring, you will see similar numbers however with older engines using a cast piston and cast rings, the typical reading will be about 15% or less. Generally speaking, anything in excess of 20% is considered worn. Although I cannot see the finish of the entire cylinder wall, based on your leakage numbers of 25%(±), -and looking at the picture of the RA finish of the cylinder walls of the non-thrust side, I would say the rings are likely excessively worn and in need of replacement. Without having the luxury of looking at valve seats and deck surfaces, all any of us can do is make guesses as to actual condition however my opinion is different than most of the comments above.

[katy]

Originally Posted by DRG-ler

Does anyone have the material composition of the liners?

Any liners I've worked with were made of cast iron, no idea about the actual composition.

[nkaminar]

Liners are propriety alloys of ductile iron. As mentioned above, cast iron has the property of taking on a smooth shiny surface. Once that surface is obtained the wear rate goes way down. Race cars will use aluminum blocks with a hard coating, like silicone carbide, for the pistons to run on, but they are throw away engines and not expected to last long. Jaguar tried that for their production cars in the early part of this century and most of those cars are now scrap. They went to putting cast iron liners (sleeves) in their engines. Lesson learned.

[DRG-ler]

Eeeiei,... sooo many answers. I try to work through the essentials from the top down.

If it was mine and it ran well and had good compression,I would not disturb it.

I firmly believe in "if it aint broke, don't fix it"

It only needs a new head gasket. Why are you trying to find trouble?

The cylinders look great with the exception of a little bit of corrosion on #2. Cast iron has a unique property in that it takes on a mirror shine after being broken in. The graphite and iron produce the shine. You only need to hone the cylinders if you are going to put new rings in and only because it helps the rings to seat.

It is precisely because of THESE statements that I am asking here. One is too fixated on modern materials. If the cylinder wall on a modern engine looked like this, everyone would say it's gone. The oil film would tear as soon as the engine was started and the pistons would seize up. Anyone who, like me, does not know the properties of the material pairing of iron and graphite will inevitably draw the wrong conclusions. So a big thank you for the explanation. I'm going to leave everything as is and only clean, dry and oil a little when assembling.

There really isn't any corrosion. That should be an optical illusion.

As for the pressure drop test (25%)... I did that a while ago. I used this tester for that. The pointer stopped at 25%, in the clearly green area. This confirms that the piston rings and valves are properly tight. No reason to make any repairs.

The carbon on the pistons is not excessive so I would say your rings and valves are fine.

But that's only been the case for the last 180km. Before everything was clearly black and full of carbon. That's a flaw I'm looking for in my carburetor. I had a replacement carburetor from my uncle for the last 180km, where the engine only uses half the petrol. 9 instead of 18L/100km. With these carburetors, everything has actually burned itself free. I will probably have to overhaul my carburetor.

What I am unclear of is if the head gasket was burned, I would assume you had either a combustion leak -or a water leak? If it was a combustion leak, is that the area I am seeing between #3 and #4 cylinder? If so, why were all the leakage readings the same? Why were the cylinder leakage numbers of the affected cylinders not different??

I also asked myself this question, especially since the pressure loss test was only carried out when the development of the noise indicated a defect! But the answer is quite simple. The pressure loss test is only tested with 2 bar. The head gasket was still sealed at first. The pressures during compression / combustion are many times higher, even with low compression. That's why the error wasn't noticed there. If I had done a compression test, I would have noticed the defective seal sooner. But I didn't have that gauge back then.

Lessons learned.

100% agree



Greetings Andy

[jack backer]

Some awful high weeds in here.. we are talking about a 200cuin L head@ 4.2 to 1 compression ratio with a cylinder pressure of about 60 psi or so..does it run good? Run it, if it doesn’t fix it.. old fashioned overhaul,hone and new rings,lap valves, adjust bearings.

Analyze it enough and you can talk yourself into… or out of… anything

[BRENT in 10-uh-C]

Originally Posted by DRG-ler

As for the pressure drop test (25%)... I did that a while ago. I used this tester for that. The pointer stopped at 25%, in the clearly green area. This confirms that the piston rings and valves are properly tight. No reason to make any repairs.


I also asked myself this question, especially since the pressure loss test was only carried out when the development of the noise indicated a defect! But the answer is quite simple. The pressure loss test is only tested with 2 bar. The head gasket was still sealed at first. The pressures during compression / combustion are many times higher, even with low compression. That's why the error wasn't noticed there. If I had done a compression test, I would have noticed the defective seal sooner. But I didn't have that gauge back then.

Andy, it appears your mind is already made up, ...which I am OK with whatever your decision is, -however for the benefit of all the other readers who will come along at a later date and likely obtain misinformation from reading this, I will post some thoughts;

To begin with, it appears you are using one of those cheap Chinese-manufactured gauges which have been proven to give erroneous readings. They are cheap for a reason. Most professional engine rebuilders (-or mechanics) would never use use that poor quality level of a tester. Mine is a OTC brand with calibrated gauges that are certified. It does not have colors on the gauges as that feature is useless. It uses a scale of 0 - 100 only. The Green, Yellow, & Red colors on your gauge mean nothing as it is all about percentages which those numbers are different between types of engines and the usage of that engine.

Next, by you telling me you used 2 bars of air pressure to test with, therein lies the issue with your test. Your gauge is designed to be operated with EXACTLY 100 psi (-approx 6.9 bars) of line pressure. For proper (-i.e.: accurate) leakage readings, this psi number is crucial as that 100 psi number is the benchmark for determining 100% -or any percentage of that. Had you used the tester properly and introduced 100 psi into the cylinder, your percentage of leakage findings would have likely risen exponentially.