Locomobile model 48 and 38 engine related topics

[Ittenbacher Frank]

a. The weight of the steel pistons used until 1923 is 4 lb. 6 oz.

b. The weight of the aluminium alloy pistons used afterwards (series 19000) is 2 lb. 8 oz.

After summarizing all the data, I believe their data is for one piston with 2 locking screws, without rings and the gudgeon pin. When comparing the naked pistons only, there was a weight saving of 42%. Considering Rings, pins and all, it is still a saving of 32%.

[Ittenbacher Frank]

4. Compression ratios

I already wrote something about compression ratios on page 2 of this thread.

https://forums.aaca.org/topic/372378-locomobile-model-48-and-38-engine-related-topics/page/2/

The point was: the thickness variation of the valve caps does influence the compression ratio by only 1%!

Domed pistons are not increasing the compression ratio as much as on "normal" (=no T-head) engines, and there is not too much space between piston and top of cylinder, watch the drawings. The distance between the inlet and exhaust valve centers on the model 48 engine is 8.3", the total width of the combustion chamber is more than 11"!

 

In the meantime I found more data related to the compression ratio:

April 1916: 26% = 1:3,85, 82.5 HP at 1800 RpM

May 1917: 25% = 1:4,00, 90 HP at 2000-2200 RpM

Aug.1923: 23% = 1:4,35, 98-107 HP at 2150 RpM

Don't be mis-leaded, there were more changes done by Locomobile, not only increasing the compression ratio. The camshafts were ground differently, with modified valve timing, carburetor and ignition, lubrication and cooling, vibration dampers and muffler back-pressure, and probably more than we can ever find out.

One last comment related to the compression ratio: 

During the 10.000 mile test carried out in 1916 by the Locomobile testing department, it was suggested " to reduce the compression from 24 1/2 to 25% (=from 1:4,08 to 1:4,00). If the higher compression ratio had given advantages, they would certainly have used that! 

Edited December 25, 2023 by Ittenbacher Frank (see edit history)

[Ittenbacher Frank]

5. Additional information which might help for searching replacement pistons

Of course you can get new pistons made specifically for your engine according to your demand and specs. Another approach (which I have done successfully on other engines) is this: Search for pistons from easily available, technically advanced and usually mass-produced engines and modify them accordingly. The advantages, such as easier availability, high quality and (usually) lower cost, and the possibility to easily buy a replacement or parts like new rings. The problem is how to find that donor engine?

Besides the cylinder diameter (4.5") and gudgeon pin diameter (1,13"), the compression height is the most important dimension for your search. This is the height from the top edge to the center of the gudgeon pin. For this value I measured 2,811" (71,4mm) at Lothar's piston.

Next I searched in the 1991-edition catalogue of KS-pistons (an old famous German manufacurer) and found two possible directions for the search: 1. Caterpillar, if your bores are still standard or sleeved back to standard. 2. Scania if you can bore your engine to 115,00 mm which is just in between the second and third oversize offered by Locomobile. All these powerful diesel engines use gudgeon pins are far bigger than the ones on our Loco. If the Locomobile connecting rod small end doesn't allow for that diameter, then perhaps bushing the piston might work. The piston crowns are shaped for diesel engine use. See the data in the third column. For example the CAT D330A: 95,5mm compression height as now, minus 12,5mm what you can probably machine away until you get a flat crown, ends up at a compression height of 83mm. Just a bit more than Loco's original 71,4mm. I am not sure if all the excessive material can be machined off and still retaining enough wall thickness at the crown? By doing this, there is a chance for creating a domed piston. Again, just food for thoughts. Maybe someone will find out? Or one of you already tried modifying an aluminium diesel piston and knows why it won't work?

Edited December 25, 2023 by Ittenbacher Frank (see edit history)

[Ittenbacher Frank]

6. Another possibility is searching for the piston manufacturer who made the aluminium pistons for my 1916 tourer which were used during overhaul in approximately 1959/1960: See the photos with casting numbers. Does anyone get an idea who made these pistons when looking at these photos? Side note: These people knew what they did. They even drilled holes into some of the pistons, assumingly for equalizing their weight. I was told that after assembly the complete crankshaft-conrod-piston-flywheel-clutch-assembly was dynamically balanced. As a proof I found a small weight additionally welded onto the circumference of the clutch body.

[Ittenbacher Frank]

Now it is enough for today. Merry Christmas!

[alsfarms]

Hello Frank and what nice information to study during a quiet moment on Christmas morning. Your approach, to this subject, certainly points to the fact that you are an Engineer! I note from your posted information, that the increase of Locomobile 48 hp ratings for the 19000 series to 105 could be influenced/enhanced by the domed aluminum pistons used when new. Do you know or have studied to know if the cut-away pictures of the engine are accurate scale drawings? If they are accurate scale drawings, it would be very possible to determine closely what the dome enhancement is. I had not made note that the 19000 series 48 was engineered with aluminum pistons, that is most interesting. I suppose that the lighter weight of the rotating mass could also contribute to the higher full power RPM rating of 2000-2200.

Al

[alsfarms]

Hello again Frank, I am wondering if you have run a scope into the combustion chamber of your Locomobile to verify if it has a flat top or domed cast aluminum piston?

Al

[alsfarms]

With a bit of quiet time I scrounged around the internet to locate a source for either the Caterpillar D330A piston or the Saab-Scania DS8 piston.  I was only able to locate one source for Scania pistons and it was not a real good source.  I would like to explore the Scania DS8 piston further as it may be a rather good possibility for a retrofit. Do you have any parts sources that can be explored for Scania parts? This conversation can really go two directions which depend on the degree of a cylinder bore job that is needed to clean up the cylinders.  If I can get by with a simple hone job, the Caterpillar pistons are certainly a good and affordable option, and I have located a good source for them and the piston rings.  I have no problem at all bushing the piston pin fits as needed in order to facilitate fitment of the stock Locomobile rod to either available piston.  At this moment, this is all an exploratory adventure until I can determine the best, available and most affordable piston option. I am really enjoying a low key Christmas!

Al

[prewarnut]

Frank, What inducement would it take to get you to put the tourer's engine on a dyno? We need performance graphs.😁

[edinmass]

 

I would run modern pistons and ring packages on them. Also, you can manufacture new pistons to match your existing wrist pins. Just center less grind them to all one size. Saves money and is a better fit. I would NOT recommend bumping up the compression ratio on ANY T head engine. Combustion chamber issues and cross flow problems will occur. Remember this are big displacement slow turning engines. Unless you have four valves per cylinder like Stutz, Mercer, or White anything over 5 to 1 will not breath correctly. There were a bunch of guys racing T Head 4's back in the day and none of them ran high compression ratios the I am aware of. It would be best to ask an early T Head expert for more advice. Unfortunatly they are few and far between. And ask someone who has actually built engines, too many internet experts using google search giving out advice. I would also add a modern oil filter set up on the build if possible......even if it's a bypass filter something is much better than nothing. Ed

[jrbartlett]

Some years back I had a discussion with Phil Hill regarding Locomobile compression ratios and pistons. He had a 1925 Sportif that he had modified with domed pistons and three carburetors. Other area collectors told me that Phil's Loco would really fly. Phil indicated that he cut a groove in the domes to ensure sufficient combustion and cross flow given the wide combustion chamber. I suspect that his car had a 3.06 or 3.07 rear end gear ratio, as this was the ratio of a spare Phil Hill gearset that came with the 1919 Sportif that I later bought. My car had a standard 3.2 ratio, but after chipping off a tooth I installed the Phil Hill gearset last year. That's about all I remember about the conversation, other than the fact that I offered to buy his Loco, but he turned me down. He seemed like a nice fellow. 

[Ittenbacher Frank]

On 12/25/2023 at 6:27 PM, alsfarms said:

Hello again Frank, I am wondering if you have run a scope into the combustion chamber of your Locomobile to verify if it has a flat top or domed cast aluminum piston?

Al

You don't need a scope (endoscope), just look or use your finger. The combustion chamber is lage enough...after you removed one valve cap. My Tourer (with aluminium pistons as shown above) seems flat as well as the Sedan.

[Ittenbacher Frank]

23 hours ago, prewarnut said:

Frank, What inducement would it take to get you to put the tourer's engine on a dyno? We need performance graphs.😁

Dear Dan, I am not planning to put the engine anywhere but on the normal road. I am satisfied with the road performance, that is enough for me at this moment.

See the official performance chart: 82.5 HP for 1915. Additionally I can tell you: My tourer's weight is 2480 kg, plus 2 people, assume 5800 lbs. Rear axle 3.85. On a 1:10-gradient there is still some acceleration in high gear. This is nice but not all you need. Low-end-torque and smoothness shall not be forgotten. Yesterday I was forced to follow a bicycle for some time. Slightly uphill, 4th gear, perhaps 10 mph? When a gap in the oncoming traffic appears, you just step on the accelerator and go. No shaking or vibrating or sputtering. You get used to this kind of driving like with an automatic transmission.

Edited December 27, 2023 by Ittenbacher Frank (see edit history)

[Ittenbacher Frank]

On 12/25/2023 at 4:45 PM, alsfarms said:

Hello Frank and what nice information to study during a quiet moment on Christmas morning. Your approach, to this subject, certainly points to the fact that you are an Engineer! I note from your posted information, that the increase of Locomobile 48 hp ratings for the 19000 series to 105 could be influenced/enhanced by the domed aluminum pistons used when new. Do you know or have studied to know if the cut-away pictures of the engine are accurate scale drawings? If they are accurate scale drawings, it would be very possible to determine closely what the dome enhancement is. I had not made note that the 19000 series 48 was engineered with aluminum pistons, that is most interesting. I suppose that the lighter weight of the rotating mass could also contribute to the higher full power RPM rating of 2000-2200.

Al

Dear Al, I used the quiet Chrismas day for uploading the stuff. Investigation and preparation took several days and even more nights in advance.

I like to ask you for two things which you can easily contribute to this topic:

1. share the engine-related papes of the series-19000-spare part book.

2. measure one of your series-19000-pistons in the same way I did (same positions, once in longitudinal direction and then crosswise, put them into an Excel-table for comparison.

Then we can all learn from the factory updates.

[Ittenbacher Frank]

21 hours ago, edinmass said:

 

I would run modern pistons and ring packages on them. Also, you can manufacture new pistons to match your existing wrist pins. Just center less grind them to all one size. Saves money and is a better fit. I would NOT recommend bumping up the compression ratio on ANY T head engine. Combustion chamber issues and cross flow problems will occur. Remember this are big displacement slow turning engines. Unless you have four valves per cylinder like Stutz, Mercer, or White anything over 5 to 1 will not breath correctly. There were a bunch of guys racing T Head 4's back in the day and none of them ran high compression ratios the I am aware of. It would be best to ask an early T Head expert for more advice. Unfortunatly they are few and far between. And ask someone who has actually built engines, too many internet experts using google search giving out advice. I would also add a modern oil filter set up on the build if possible......even if it's a bypass filter something is much better than nothing. Ed

Dear Ed, thanks for your input. I fully agree. Please share more from the old expert's knowledge.

One question: You suggest to use modern ring packages. Does that include chromed rings, or do you specifically ask for non-chromed rings? I was told these rings with hard chrome surface works well in modern liners but will damage the bores of old engines which have no liners. Is that true? Does that apply to Locomobile engine blocks? Somewhere I read the bores were treated, not just drilled into soft cast iron. I am keen to learn more about these experiences.

[Ittenbacher Frank]

9 hours ago, jrbartlett said:

Some years back I had a discussion with Phil Hill regarding Locomobile compression ratios and pistons. He had a 1925 Sportif that he had modified with domed pistons and three carburetors. Other area collectors told me that Phil's Loco would really fly. Phil indicated that he cut a groove in the domes to ensure sufficient combustion and cross flow given the wide combustion chamber. I suspect that his car had a 3.06 or 3.07 rear end gear ratio, as this was the ratio of a spare Phil Hill gearset that came with the 1919 Sportif that I later bought. My car had a standard 3.2 ratio, but after chipping off a tooth I installed the Phil Hill gearset last year. That's about all I remember about the conversation, other than the fact that I offered to buy his Loco, but he turned me down. He seemed like a nice fellow. 

Dear James, nice to hear froom you again! I didn't know you had to work on your Sportifs rear axle. I only knew about chutch trouble. How did you solve that?

Now you changed from 3,2 to 3,07. How much difference do you feel on the road? Your feedback is very much appreciated! Kind regards Frank

[alsfarms]

I will attach relevant pages from the 19000 Series manual, hopefully later today or evening.  As for comparisons sake, I am not yet ready or in a position to remove a jug from the 1925 48. When I get to that point, I will fully measure and post supporting pictures of the development and changes made to the last of the Locomobile 48 series pistons. My.... the torque of these Locomobiles is simply impressive, as you say loping along at 10 mph and being able accelerate without the typical rebellion found in more modern automobiles. The Sportif, James spoke about, must certainly be a very roadable car with the gearing he suggests. I remember wanting 3:08 gears in a 1957 Chevrolet, years ago. When I made that change, it was good for economy if driving on the flats, but not so great driving in the mountains, of which we are known for. This Chevrolet had a stock 220 HP 283 engine and a four speed. The torque curve and power band is very different from that of a Locomobile 48! As I recall, the 3:08 gears were next changed for 3:55 gears which resulted a a much funner driving car and acceptable fuel economy. On a side note, I have in the works another 283, 270 hp for my most modern project.

Al

[jrbartlett]

In response to your queries, when my 1919's clutch would no longer disengage I found a fellow in Arizona who was experienced in multi-plate clutches from the teens. I've never worked on such a clutch, and felt it better to consult with someone who had. I took the car to him and he tore it down and removed all the discs and relined them, for both the clutch and the clutch brake. Incidentally, the problem with my clutch appears to have been simply decades accumulation of dirt and dried grease. But there are no openings in the clutch housing through which to wash out everything. You have to remove the entire unit to get at it. He also addressed some transmission and rear axle leaks. When he tore down the rear end he found a chipped tooth on the 3.2-to-1 ring gear. Fortunately I had brought the spare 3.07-to-1 ring and pinion with me, so he installed it. After picking up the car, the following week we drove it on the 2022 Glidden Tour in New Jersey, running about 500 miles on twisting hilly roads, so I really couldn't go over 40 MPH very often, especially considering the 2-wheel brakes. But the Arizona fellow had driven it at 55, and he said it was "a big, long-legged car that will outrun a Simplex." I don't know about that one -- Ed says it depends on which Simplex. But driving-wise I can say that the car seems most comfortable if I start off in first, which of course is good for only about 5 MPH, and at any speed up to 45 the engine seems to be loafing. Of course any big, old, high-off-the-ground car can be inherently unnerving to drive at speed. Several years back I did get the car up to 70 once, on the former 3.2 rear axle ratio, and more was there from the car, but certainly not from me. No desire to drive faster than 50 or so. Some of the California Loco crowd told me that Phil Hill routinely drove his Loco "well over 75," but he was fearless given his racing expertise. Incidentally, my '25 Loco is a far different driving experience than the 1919, with easier steering, clutch, shifting and brakes. It's owner in the 1960s (whom I knew) said he had frequently driven it at 70 on tours in the western U.S.    

[Ittenbacher Frank]

4 hours ago, jrbartlett said:

In response to your queries, when my 1919's clutch would no longer disengage I found a fellow in Arizona who was experienced in multi-plate clutches from the teens. I've never worked on such a clutch, and felt it better to consult with someone who had. I took the car to him and he tore it down and removed all the discs and relined them, for both the clutch and the clutch brake. Incidentally, the problem with my clutch appears to have been simply decades accumulation of dirt and dried grease. But there are no openings in the clutch housing through which to wash out everything. You have to remove the entire unit to get at it. He also addressed some transmission and rear axle leaks. When he tore down the rear end he found a chipped tooth on the 3.2-to-1 ring gear. Fortunately I had brought the spare 3.07-to-1 ring and pinion with me, so he installed it. After picking up the car, the following week we drove it on the 2022 Glidden Tour in New Jersey, running about 500 miles on twisting hilly roads, so I really couldn't go over 40 MPH very often, especially considering the 2-wheel brakes. But the Arizona fellow had driven it at 55, and he said it was "a big, long-legged car that will outrun a Simplex." I don't know about that one -- Ed says it depends on which Simplex. But driving-wise I can say that the car seems most comfortable if I start off in first, which of course is good for only about 5 MPH, and at any speed up to 45 the engine seems to be loafing. Of course any big, old, high-off-the-ground car can be inherently unnerving to drive at speed. Several years back I did get the car up to 70 once, on the former 3.2 rear axle ratio, and more was there from the car, but certainly not from me. No desire to drive faster than 50 or so. Some of the California Loco crowd told me that Phil Hill routinely drove his Loco "well over 75," but he was fearless given his racing expertise. Incidentally, my '25 Loco is a far different driving experience than the 1919, with easier steering, clutch, shifting and brakes. It's owner in the 1960s (whom I knew) said he had frequently driven it at 70 on tours in the western U.S.    

Thanks a lot, James! Regarding the clutch: Yes, absolutely true.

Even today we have similar issues when designing our road milling machines which have most machine functions operated hydraulically except the drive to the milling drum with all these hundreds sharp picks which cut the asphalt surface: 75-90% of the engine power (500-1000 HP, depending to machine size) is transmitted through a dry multi-plate clutch to the milling drum which is really large and weights several tons. We have to achieve enough air flow through the clutch to cool the discs and transport the disk's worn material away, but avoid road dust entering the clutch and getting stuck in places where it can affect the disk's free movement.

On the Locomobile we have another issue to consider: Oil mist from the engine or grease from the throw-out-bearing or cross shaft shall never enter the clutch discs! Therefore Riker has closed the clutch housing. Periodic cleaning is required. I did this on my tourer and found very little dust inside. Lothar had done that on his speed car and found it full with huge quantities of dirt. You found cleaning necessary, too. We should call it "preventative maintenance" and just plan to do that when circumstances allow for that work. Maybe after 10 years or 10.000 miles it might be a good idea to plan for that. An inspection pit with lifter is recommended because the clutch unit is really heavy and a tight fit in between flywheel and transmission. The work itself is not complicated. I explained that in an earlier post and showed my self-made tool for releasing the spring pressure.

Regarding the rear axle ratio: Please don't mis-understand my question about lower ratios: I am not planning to reach the highest top speed or win any race, but I like the advantage of reduced engine speed at the same cruising speed. Your experience is most welcome for evaluation which ratio is still ok and usable without compromising acceleration or hill climbing abilities. Al explained what happened with his Chevy if you try a very fast ratio in mountain areas: Poor performance, no fun, you lose more than you gain. 

One question: Do you know the weight of your Sportif?

I like to add another consideration which I learned when operation a large fleet of off-highway-trucks in mountainous area: If the average engine-RpM is reduced by lowering the rear axle ratio, then the water pump speed is reduced, too, and you can probably find operating temperatures (water and oil) increasing! But the necessary torque required from the engine is increased. There were reasons why Locomobile offered so many different ratios for their cars.

[jrbartlett]

My 1919 Sportif weighed in at 5,400 pounds with a quarter-tank of gas, and no passengers. I checked it on a truck weight scale. 

 

In contrast, my '32 Duesenberg weighed 6,000 pounds, with 3,000 on each axle. 

[prewarnut]

I scanned the series two carburetor manual for late 1915 and beyond cars. Hope this may help.

 

[prewarnut]

Part 2.

[rydersclassics]

A couple of months ago I had a very good looking set of cylinders cleaning tanked and then magnifluxed for good measure.

This revealed a barely detectable hairline crack that otherwise would have gone undetected. Unless addressed it would not be stable and always on my mind.  

 

After drilling the first stop hole at the end of the crack and cleaning to locate the other end I found the crack was two and five eights inches long and the water jacket wall looked very thin. I measured the thickness and found it to be 145 thousandths. Now I know why people are looking for good cylinder blocks.

 

I decided to tackle my water jacket crack with a kit from Lock N Stitch Inc.

If you haven't heard of these people they do all types of industrial repairs worldwide and manufacture everything in house. I'm told only in the US.

 

I had known about Lock N Stitch Turlock Cal. for a while so I got in touch with their tech department and discussed the best approach for my situation. 

Given the circumstances of old thin casting and the rarity of these blocks, they were very cautious and helpful with guidance as to the correct pin system package and tutorial for this job. 

With the risk involved I decided to sink or swim on this one, who better than me to ruin my part? 

 

It took 25 pins and the better part of a full day waiting fifteen munities between each pin for the locking sealer to dry before grinding flush then moving to the next.

 

Should be good to go!

 

 

 

Edited February 2 by rydersclassics (see edit history)

[alsfarms]

Hello Steve,

I can't get your above posted pictures to open showing the end results of your pinning repair.  Could you give it another shot?

Al

[rydersclassics]

[alsfarms]

Nice work Steve,

How soft are these repair pins? Is it easy to drill into the casting and take part of the pin with it? Do you feel that the thin casting was a result of pattern shift during the casting process or due to degradation of the cast material over time? I can't determine, where is this crack located on the jug? I am guessing along the bottom of the water passage.

Al

[rydersclassics]

 

 

Good questions Al.

Here is a picture to clear up the crack location.

I have 1 set of 48 blocks and 1 set of 38 block that have severe freeze damage, not like this although the casting thickness in the area is comparable.

It's not a freeze crack in my opinion and this set of cylinders have no visible wear or sighs of neglect or abuse.

 

This engine was dismantled before I acquired it so who knows how many people handled it, moved it, or how careful the were.

It wouldn't take much of a blow to crack one of these even getting heavy handed trying to remove the valve cap might result in a stress crack in this area.

Yes I have seen many 100 plus year old castings cylinder and heats cracked so cast iron seems deteriorate with lots of time and become more brittle (embrittled). Lots written on this topic. 

Not being a metallurgist I will leave the debate to others.

 

I will say handle your cylinder blocks with great care! 

 

Starting the drill into the pin and casting was easier than I had expected and the hardness of the pin is comparable to that of the casting. The tricky point was when the drill goes through the back side of the wall.     

 

Check out the Lock N Stitch website they have a lot to offer and a variety of pin systems depending on application.

 

 

 

 

 

 

 

 

 

[Ittenbacher Frank]

Well done, Steve! Considering the amount of rust on the hollow bolts on top of the cylinders,they are in really good shape.

On my tourer which was obviously never neglected or in bad condition, and at least during the last 30 years filled with antifreeze, the shaft thickness above the hexagon had become quite thin and even the corners of the hexagon were partly rusted away! Yours look quite ok in this regard.

[alsfarms]

Steve, I agree, if you likely had a frozen block event, normally, you would see the crack running horizontally along the bottom of the water passage. So far I do not have the need to make a crack repair, like your repair, but honestly it is only a matter of time. Your craftsmanship has reassured me that a semi difficult repair can be completed!

Al

[alsfarms]

Here is my update on my effort to source affordable and ad adaptable 4.5" pistons for use in a Locomobile engine project. I am in touch with a group who checks availability of new manufactured diesel pistons.  The two pistons that I am feelers out for are a Caterpillar D330A and a Saab-Scania DS8.  Hopefully I will have a response shortly that will tell me if new MFG. pistons are available and at what price.

Al

[alsfarms]

It has snowed so I have a bit of time to devote to this search for pistons.  I am surprised how quickly I have a good response on available after market Caterpillar pistons.  The current inquiry has an aftermarket Caterpilar piston, for a 4.5" bore engine.  The price quoted is $97.60.  The parts desk is sure that he can better that price and I am currently waiting for an updated price.  This source is also looking for the Saab-Scania DS8 piston as a second possibility.  I may be in business on this Locomobile engine rebuild sooner than I thought possible.

Al

[alsfarms]

Today has been fruitful! My source for aftermarket pistons has reached out to his sources and has found a source for the Caterpillar D330A, 4.5" pistons for $93.40/ea. Several considerations for the use of this piston is one, if the existing bore, cleaned up and serviceable at the factory 4.5" to match this piston. Next the ability/cost to cut down the dome to be workable in the "T" head engine. Last bushing down the wrist pin fits to be compatible with the Locomobile wrist pin and connecting rod. With some machine shop estimates and what I have the skill to complete, I will soon know if this modified diesel piston is a valid option from a simple cost standpoint for fitting into a Locomobile rebuild as an option for a full set of custom pistons from a custom piston manufacturer.

Al

Edited February 9 by alsfarms
Spelling (see edit history)

[alsfarms]

Here is the latest on the replacement Locomobile 48 piston subject. A source for new Cat diesel forged aluminum pistons p/n 2m5558 with a 4.500" bore has been found here in the US. They can be had for around $65. Per each, bare. Suitable rings will need to be sourced to work in the cast iron Locomobile jugs. Modern rings may not be good as they may wear the cylinders to fast. The good news is I will have a set of these "test but not proven" pistons in hand Monday of next week and will begin a serious comparison with a stock Locomobile cast iron 48 piston. I am anxious to see where this evaluation leads this piston discussion.

Al

[alsfarms]

I have just received confirmation that the Cat pistons I ordered, as a possible replacement for the original Locomobile cast iron pistons,are scheduled for delivery tomorrow. I will provide more information and comparisons tomorrow. It is my hope that this can be a workable option for those needing to complete an engine rebuild on a Locomobile 48.

Al

[alsfarms]

Ok, the 4-1/2" OD pistons arrived today. I am very impressed with this vendor. I will first post pictures then add some raw measurements for comparison purposes. I am not thinking that these pistons will work on a stock Locomobile 48. I am sure they will work for my application, however.

Al

[alsfarms]

Picture 1

[alsfarms]

Picture 2

The wrist pin bosses are thick enough that a threaded hole can be installed to work as a keeper for the wrist pin bushings. That reduces the wrist pin problem.

Edited February 27 by alsfarms
Clarity (see edit history)

[alsfarms]

Picture 3

It appears that these pistons are fitted with some type of top compression wear control liners for the top compression ring groove. Probably very important for use in a diesel high compression engine.

Edited February 27 by alsfarms
Clarity (see edit history)

[alsfarms]

Picture 4

After some measurements, most of the diesel dome shown here can safety be removed leaving a flat a piston or some roo. For a slight dome as with the 1925 Locomobile 48 aluminum pistons. This is encouraging for me.

Edited February 27 by alsfarms
Clarity (see edit history)

[alsfarms]

Picture 5

What a very different piston ring configuration between a Stock Locomobile 48 piston as compared to a modern Cat diesel piston. The weight of the Cat piston is 3.13 lbs bare whereas the stock cast iron Locomobile 48 piston is 5.8 lbs bare.

Edited February 27 by alsfarms
Clarity (see edit history)