Conrod bearings on a 1922 Cadillac

[hidden_hunter]

Hi guys,

 

I've pulled the conrod bearings off my 1922 Cadillac (Type 61)

 

It looks like there is plenty of meat on them and they're fairly evenly worn, however when my rocker gear decided to shear off it spread metal into one of the bearings.

 

What should I do? Ideally get them repoured or would it just wear down on the bit that had the contamination (that I've now removed)? Would I need to remove the crank?

 

 

[edinmass]

Lots of issues to resolve. If the mains are clean and show no problems, you can probably get away with just doing all the rods. Be sure the throws on the crank are round, if they are too far out of round you  will have to turn the crank. This deep in be sure to do a valve job, check the springs, and hone and re ring the motor.

[hidden_hunter]

16 minutes ago, edinmass said:

Lots of issues to resolve. If the mains are clean and show no problems, you can probably get away with just doing all the rods. Be sure the throws on the crank are round, if they are too far out of round you  will have to turn the crank. This deep in be sure to do a valve job, check the springs, and hone and re ring the motor.

 

Valves are all done, springs tested, bores honed and rings ready for install :-) I get the repaired part back that caused this all this back in 2-3 weeks so these are literally the last pieces that need to be done before reassembly.

 

Will they need the crank out of the car to pour new ones?

[Guest SaddleRider]

DANGER !

If I understand correctly what you are telling us,  a part composed of fairly hard metal failed,  and fragments  of it lodged in and are embedded in the bearing material of a connecting rod.

 

Think about how "plain" bearings work.   To work, they have to be of a dis-similar "co-efficient-of-friction".    That is why the bearing material in a "plain" bearing is a MUCH softer material than the surface it is riding on.

 

This is a basic physics problem - the relatively similar metals, in terms of hardness,  of your crank-shaft journals,  and the fragments of the hard metal embedded in your rod bearings will cause "hot-spots" that will quickly over-heat and destroy both your crankshaft journal surface, and cause the soft bearing material to "wash-out".

 

Getting rod bearings repaired is not a major crisis.    A number of companies are still around that can re-pour the "poured babbit" rod bearings.   That is the way I'd go if  I wasn't going to keep the car,  and/or if the car will only be used for puttering around at car shows,  rarely driven on public roads, and certainly not over 35-40 mph.

 

Again - it is your car and you know best what your intended use is.   If you like the car enough to drive it with any degree of regularity,  I would have a machine shop machine out your connecting rods to adapt them to handle modern "insert" type rod bearings.    Yes, it is more expensive and technically challenging to do that.   Think about this - you can be assured the automotive industry did not give up on the cheaper "poured babbit" bearing concept voluntarily ! 

 

 

 

[Rusty_OToole]

I question this. For one thing the modern shell bearings are much cheaper than poured babbit. For another, I believe the poured babbit bearings are just as durable if used as they were intended. I base this on speed and endurance records set when there was no other kind of bearings.

 

One other thing that I have wondered about, and that is, does babbit metal deteriorate over long periods of time? We are now dealing with cars that are 100 years old or thereabouts, that were designed for a working life of 10 years or so. But, babbit metal bearings have been used since the mid 19th century, what does experience say about this? Under the circumstances would it be wise to renew all the bearings? I understand they cost about $200 apiece so I wouldn't blame anyone for not renewing them if it was not necessary.

[hidden_hunter]

4 hours ago, Rusty_OToole said:

I question this. For one thing the modern shell bearings are much cheaper than poured babbit. For another, I believe the poured babbit bearings are just as durable if used as they were intended. I base this on speed and endurance records set when there was no other kind of bearings.

 

One other thing that I have wondered about, and that is, does babbit metal deteriorate over long periods of time? We are now dealing with cars that are 100 years old or thereabouts, that were designed for a working life of 10 years or so. But, babbit metal bearings have been used since the mid 19th century, what does experience say about this? Under the circumstances would it be wise to renew all the bearings? I understand they cost about $200 apiece so I wouldn't blame anyone for not renewing them if it was not necessary.

 

It's a risk question for me, what is less likely to cause issues/damage - there is always an element of danger that you're going to break something

[F&J]

5 hours ago, Rusty_OToole said:

does babbit metal deteriorate over long periods of time?

Rare but yes on the ones I have taken apart, I just can't recall the models or age of the cars, as I have looked at too many

 

What I saw was cracks, or chunks that were still held in place like a puzzle piece does.

 

I can't see his bearings in person for the rest of issues it may have..., but I sure do agree with the following quote from SaddleRider:

20 hours ago, SaddleRider said:

This is a basic physics problem - the relatively similar metals, in terms of hardness,  of your crank-shaft journals,  and the fragments of the hard metal embedded in your rod bearings

 

 

Ok, your budget?  tight, or have funds, I do not know, and don't need to know.  About the fragments of metal? Cast iron or steel? gear or is Fiber? it's unlikely of that..

 

If you had but a few metal slivers imbedded,.. that can be seen under well lit large magnifier, can you pick them ALL out with a sewing needle?   Babbit is very forgiving if there are very slight ridges showing where the sliver was embedded.. Fine scotchbrite from a 3M supplier, years ago the only choice was super fine steel wool. 

 

Rods were often mickey moused on the side of road, on a long trip by the po' folk.  In worst cases a piece of leather got them to California...

 

Your call.  Your car, your funding,    Measure everything, no matter what you have not decided on yet  

[edinmass]

The rods can be Babbitted without removing the crank. Simple job. Be sure you get someone who has LOTS of experience in prewar cars. 

[Rusty_OToole]

Bearings can be scraped smooth and fitted with bluing. This used to be common practice. Remove shims, or file the mating surface and create a new bearing surface by scraping off high spots revealed by the Prussian blue. I don't know where you would find someone who knows how to do this today.

[hidden_hunter]

2 hours ago, edinmass said:

The rods can be Babbitted without removing the crank. Simple job. Be sure you get someone who has LOTS of experience in prewar cars. 

 

The rods don't connect directly onto the crank, they clamp onto these shells - the babbit surface there is the one that goes onto the crank. Is it still possible to do them without removing the crank?

 

The top photo is the worst bearing, it's got about 5x1x1mm worn from around the oil hole and a 5x1mm drag

 

To get the crank out of the car involves removing the entire motor (which also involves removing the rear fender...)

[C Carl]

4 hours ago, F&J said:

,    Measure everything, no matter what you have not decided on yet  

 

This is non-negotiable. From what I see , re-using these bearings is a definite maybe. I have seen worse bearings come out of running engines , but they did not go back in. But you MUST see if the clearances are still COMFORTABLY within spec. If so , and no out of round problems , there may be quite a bit of life left , under certain conditions. Go easy as practical on the old engine. Avoid high BMEP , (Brake Mean Effective Pressure , call it  torque if you like. This is a measure of combustion piston load) , and high manifold pressure. Keep your rev's down within reason. These old cars are most fun slowly going nowhere in particular , or anywhere you can enjoy 25 - 35 mph. Above that , the flat crank vibration begins. In the case of your engine , that puts extra load on the center main bearing. What is the existing clearance clearance HERE , where all things equal , the most wear will be present ?

 

Use conventional multi-viscosity detergent oil for the first 4000 miles + on the recently honed cyl walls , then change to the very finest synthetic oil in a multi-viscosity suited for your clearances yet to be measured/plastigaged. Keep engine temps low. Many ancient local Sunday drive/parade cars get treated to new radiators before seeing long distance tour service. Here you see how cool the new radiator kept my '27. Temp up in the high 90s , strong headwind , later afternoon , speed 25. This is about as hot as it got. At one point climbing a steep winding grade , my backup mechanical temp gauge read 175. It might be a very good idea to have your machinist friend make a new oil pump housing , and put in a full-flow oil filter. A large area 20 - 30 micron medium , and change with frequent oil changes. Maybe 500 miles , 1000 , 2000 , and of course the synthetic change at 4000 + miles. The full-flow filter is relatively easy to install on these cars , shown here is my '24. Your present oil pump housing is identical to what was replaced on my car. Particularly if you are able to use the existing bearings , a substantial oil cooler should be put inline also. Incorporate an easy priming fixture here , too. As far as you have taken your engine down , most of your internals will be clean. At your first annual oil change of synthetic to synthetic , get an oil analysis to establish a baseline. Do so every year to monitor engine wear. 

 

Please allow low me to quote Frank again : "MEASURE EVERYTHING , NO MATTER WHAT YOU HAVE NOT DECIDED ON YET." (Emphasis mine). And please report back to your helpful forum friends here. We all admire your young "can do" attitude. Way back when we were your age , there was no internet. Learning came more slowly. You are acquiring knowledge and experience very quickly. When you are our age , it is possible you will know more than today's old folk do. Just keep asking , and stay hands on. The more you do , the more you will be able to teach the young'uns , 20 , 30 , 40 , or 50 + years from now !  - Carl

 

[hidden_hunter]

I have another Type 61 crank available to borrow, is it possible to use this to pour new bearings if the wear is similar and then just scrape them to fit my crank? 

 

Just trying to weigh up all of my options and the least risk short and long term :-)

[F&J]

3 hours ago, C Carl said:

From what I see , re-using these bearings is a definite maybe. I have seen worse bearings come out of running engines , but they did not go back in. But you MUST see if the clearances are still COMFORTABLY within spec. If so , and no out of round problems , there may be quite a bit of life left , under certain conditions. Go easy as practical on the old engine. Avoid high BMEP , (Brake Mean Effective Pressure , call it  torque if you like. This is a measure of combustion piston load) , and high manifold pressure.  These old cars are most fun slowly going nowhere in particular , or anywhere you can enjoy 25 - 35 mph. Above that , the flat crank vibration begins. In the case of your engine , that puts extra load on the center main bearing. What is the existing clearance clearance HERE , where all things equal , the most wear will be present ?

Carl put the most important info in his first paragraph above in this Quote ^^^

 

A Bearing, no matter if poured Babbit or "babbit inlay" of a modern replaceable "shell" bearing, can run and last "forever" non-stop, if it ran in a total-loss fresh oil system (that does not exist).  A crank journal surface is never in direct contact with the two types of babbit....Due to the oil film later. Never, unless you pay attention to what he said about "loads".  The early Chevy six rodders found that out about "loads" when they spun tires in dirt on side of the road, then instantly had the spinning tire hit hard pavement.  That shock "pounds" the softer poured  Babbit which is  " a thicker-more compressible mass".   That compressibility was the reason some rod companies touted the centrifugal "pouring" of their new babbit process, to give a stronger mass.

 

 Carl said: "Keep your rev's down within reason.".  Please everyone listen to him.  People on AACA have posted that "my buick/chev/ford with the stock rear ratio can easily run 70 ". Think about the massive force on a battit rod's  soft "mass". as the piston changes directions at top and bottom of the stroke.  And how it multiples with RPM increases.

 

Mains can get hammered badly if you show your buddies how your old car can chug till almost stopped, going up your toughest hill in town.  That is fact.  Rods suffer too then, but the mains don't suffer as much with too high of RPMS,  " IF" it has a counterbalanced crank.

2 hours ago, hidden_hunter said:

I have another Type 61 crank available to borrow, is it possible to use this to pour new bearings if the wear is similar and then just scrape them to fit my crank? 

I have only done "spot repair" of an early babbit engine....meaning if just one rod let go.  I make a inner mandrel out of some size item that will leave enough babbit to machine on a Mill or in my case a drill press with a sweeping cutter.  The outer part of the exposed babbit on a rod is the side thrust areas.  I make some sort of wooden hardwood "mold" (because wood can often work on a single pour and faster to make)to have those two sides be poured oversise, so I can machine those too.   I have never heard of someone using a crank to pour on a "car" engine but very few people I ever talked with have even tried doing babbit..(except local Pop-engine guys did some, "on crank"), .so I can't advise on that.

 

A rough pour would need a real close-to-finish-size of the inner mandrel that I spoke of...(if a bearing knife is to be your only tool)

 

People learn new things by trial and error, is all I can say.

 

If your crank has round journals like Carl has said they need to be, and if you have no babbit on rods/mains that is worn too sloppy, or is out of shims or non-adjustable....I'd clean the babbit and run it....unless you are going on the Great Race type demands,...  But that would be MY call on MY car, not yours perhaps, as if you being "a local customer of mine".      "perhaps"  ...

Edited May 23, 2017 by F&J (see edit history)

[hidden_hunter]

Had the bearings looked at today, they said to repour them they would want the whole crank and case to do it - really not sure what to do :|

[C Carl]

Measure all rod brgs. and throws at several points with high quality digital inside and outside mic's/calipers. Purchase high quality ones , and they will serve you well over the coming decades. Remove the main brg. caps and examine closely. Plastigage these at a couple points , maybe 90 to 120 degrees apart at the same time. Report findings back to us. That is unless the shop which looked at the brgs. says they must be replaced. If that is what you must do , make sure to balance everything to play it safe.   - Carl

[hidden_hunter]

19 minutes ago, C Carl said:

Measure all rod brgs. and throws at several points with high quality digital inside and outside mic's/calipers. Purchase high quality ones , and they will serve you well over the coming decades. Remove the main brg. caps and examine closely. Plastigage these at a couple points , maybe 90 to 120 degrees apart at the same time. Report findings back to us. That is unless the shop which looked at the brgs. says they must be replaced. If that is what you must do , make sure to balance everything to play it safe.   - Carl

 

I can't actually get the bearing caps off, they're stuck on tight and I didn't really want to run the risk of snapping them off.

[C Carl]

Do you have any of the old AACA guys living near you ? I thought Bernie Jacobsen was not far from you ? It sounds like you could use an old helping hand at this point. It must be frustrating at times. From being told it was "ready to drive and enjoy" to have to do so much work. Obviously it is more of a project than you would have liked. But do it right. Stick with it , and the knowledge and pride in a job well done will , in the end be well worth the effort. You have many driving seasons ahead of you. Once you know that engine well , and have got everything right , you may even look back at your success , glad to have it work out as it has. I would think that at least 1/2 of us found ourselves in deeper water than we might have wished. I guess whether you swim or sink separates the car guys from the cow girls. Just don't take any short cuts. With putting something so old back on the road you ALWAYS have to start by dismantling to a certain level. You generally find some things better , and some things worse than expected. We all hope your mains are better , and will serve you well. Take your oil pump apart. It is one of the easiest things to do. Tolerances must be very close there , and it is a rather low pressure , low volume pump. Not much margin for slop. Oh , and those cow girls. Nothing wrong with them. I have one of 'em myself. I hope I am not being insensitive and politically incorrect , but I am glad Sandy is not a car guy.   - Carl

[Guest SaddleRider]

On ‎5‎/‎22‎/‎2017 at 0:27 PM, Rusty_OToole said:

I question this. For one thing the modern shell bearings are much cheaper than poured babbit....... For another, I believe the poured babbit bearings are just as durable if used as they were intended. ....

 

I respectfully suggest you are giving this fellow bad advice.   Let me give you a little background - I apprenticed in an auto machine shop as the "poured babbit" era was drawing to a close.    So I have some familiarity with the issue.     I trust you are well aware that the practice  of engine manufacturers of using poured babbit connecting rods ended many decades ago - for good reason, even tho it is far more expensive to go the modern route of "insert"s. 

 

Service life at the road and engine speeds becoming commonplace by the mid 1930's is the primary reason - my recollection was that the last "hold outs" were Chevrolet and Buick  in the early 1950's,   An outstanding example of what happens to "poured babbit rod bearing" equipped cars when driven at higher road speeds than they were designed for can be found in news items discussing the opening of the first sections of the Penn. Turnpike in the late 1930's.

 

 I do agree with your logic in this sense - that when only "poured babbit" type rod bearings were available..yes,  that is what people used. 

 

And I do agree with your comment about "durable if used as intended" - with the higher nickel content bearing material they used in those days - yes if you are willing to accept puttering around on the roads of that era at the speeds of that era,  and accept that the engine will be all done by, oh. in those days....say...30,000 miles.

 

I am unclear how you arrived at the comment that 'MODERN SHELL BEARINGS ARE MUCH CHEAPER THAN POURED BABBIT".    You are mistaken.  The machine-work and engineering - new motor or repair - to manufacture what you call a "shell" bearing and make a connecting rod to accept it, is far more costly and complicated than merely "tinning" a "lower end" of a connecting rod and then boring out the soft bearing material to a given "spec".

 

As I suggested above,   I  understand (but most certainlly do not agree with)  the thinking behind folks willing to accept the much less espensive "poured babbit" solution to getting a old car's motor done.  It is cheaper & faster than, again, the more complex machine work to "do it right".   Yes, "do it right" - again, the entire automotive/truck industry world-wide long ago recognized "insert" type rod bearings are so much more durable.   As I noted,  if a car's intended use is primarily only to run from a trailer to a show-field,  some car owners feel it makes no sense to go to the more costly, labor-intensive process of converting to "insert" type bearings.

 

One major engine maker I am familiar with went to great lengths and production expense to try and save the concept of "poured babbit" rod bearings.   They tried ever more powerful oil pumps,  oil coolers,  finned rod caps,  and so on.    They finally gave up, and for their 1935 products, went to the "insert type" rod bearing .  The difference was significant - whereas the previous year's production ( the same engine except for the rods !)  was good for less than 2,000 mi. at high speeds,  the 1935 equiv.  with "insert" rods went wide open for a famous 25,000 mi endurance test, at the end of which the motor was disassembled, with the following quote from the examining engineers " could be reassembled with the same parts and run the test again".

 

Bottom line - let's encourage this fellow to get his rods and crankshaft to a competent machine shop, and "do the job right".

 

 

[Grimy]

Saddle Rider, on the other hand consider the durability of the babbitted rods in the Pierce factory V-12s run at Bonneville in 1932, 33, and 34.  The cars were DRIVEN back to Buffalo and the end of those runs.

 

Purity of the babbitt in new pours is especially important.  In my experience, where I have found chunks of bearing material coming loose, those engines had been left sitting for decades, or with very dirty oil, so it is likely that the deterioration arose from acid contamination of the oil.

 

Only if I were planning a COMPLETE engine rebuild would I consider converting babbitted rods to insert type.  And I am indeed preparing for a complete rebuild of my 1925 Pierce 80, and I will NOT convert to inserts.  Over a period of 21 years, I got over 20,000 miles out of a marginal (when acquired) engine with well-worn rod bearings--and I drove some strenuous miles.  Perhaps if I planned to drive a car 50,000 miles or more, I would consider converting.

 

For a partial rebuild (not removing the crank), I'd definitely re-babbitt.

 

As to the costs you cite, conversion is indeed more expensive because of the machining costs and thrust surfaces for the initial conversion; the insert costs are negligible; but a subsequent insert replacement job (we should all live so long!) would be relatively inexpensive.

[Rusty_OToole]

Last I heard, to have poured babbit bearings redone costs $200 apiece. Shell bearings about 1/10 that.

 

I don't know how one would go about altering an old rod to take insert bearings, and whether it would cost more than a new poured bearing.

 

I thought the first car with shell bearings was Chrysler in 1934.

[Grimy]

$200 Canadian :-(, Rusty, about $125 per rod in the US