JV Puleo

My 1910 Mitchell "parts car" project

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The gaskets/o-rings arrived so I did a trial assembly.

 

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It looks really good. I'm confident it won't leak but, of course, we won't know for certain until the engine is done and I run it.

 

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I've one more piece to make tomorrow but then I'll go on to the exhaust manifold. I can't finish the intake until I get the bronze castings for the replacement flanges. When those are done and the polishing finished I will solder it all together. That will almost certainly be done on the engine with everything socked up... there are too many parts here to take a chance on anything moving.

 

Edited by JV Puleo
typo (see edit history)
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Your Mitchell has a very unique intake and other plumbing.  Your going to have a very nice set-up!  Your crankcase looks very solid like they used a good quality aluminum in the casting process.

Al

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The casting is on the thin side... lighter than others I've looked at. I'm not thrilled with it but that is what I have to work with. I am pretty sure they used the cheap aluminum, but, as it turns out, that isn't bad. The alloys available in 1910 were very limited and the one that was considered the "best" has not aged well. Simplex used that alloy. Today, their transmission cases and engine blocks are prone to cracking and are, to my knowledge, unweldable. I am hoping that with considerably less running stress from lightened reciprocating parts and better balance there won't be any problems. Still, when I get to the crankcase machine work (I have to put my vertical mill back together first) I will probably put bronze sleeves in as many of the threaded holes as I can. Threading direct into aluminum was recognized at the time as being a poor idea but, it was cheaper and I'm convinced that where this engine is concerned the Mitchell people ALWAYS chose the cheap alternative. The metal itself is very porous. In fact, it was painted with aluminum paint, traces of which remain, to keep oil from leaching through it. I will paint the inside and outside of the engine but there is also a process by which aluminum castings are impregnated with a resin (similar to fiberglass resin) under extreme pressure completely eliminating porosity. I had it done many years ago to a RR Phantom I head. Oddy enough the company is here in RI, in East Providence now, though years ago they were across the street from my old printing plant. They also do vapor degreasing, so when the machine work is done I'll have the case thoroughly cleaned and impregnated. I'm concentrating on the peripheral parts of the engine, partly to gain experience before tackling the rods, pistons and main bearings but also because when those are ready I want to reassemble the engine as quickly as possible. I don't want it sitting around the shop partly dismantled.

 

There are probably reasons why the engine was only made for two years... I suspect it had a lot of problems though I also suspect this had more to do with slipshod workmanship than design. The design itself is pedestrian... with very little about it that can be thought of as innovative.

 

What they didn't have was pot metal... they used Babbitt in places where it was inappropriate but, in the end, they had to use aluminum, cast iron, and steel because that was what was available.

 

jp

 

 

Edited by JV Puleo (see edit history)

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I thought up this addition to the intake manifold... As I was assembling it I realized that, since the tubes are round, orienting the carburetor flange so that it was always parallel to the ground could be a problem and that, in order to keep the float level, this was very important. I got a wider piece of 1/8" brass sheet and made a plate the width of the flange that will bolt to the engine sub-frame in the same position as the temporary one shown above. This also serves to support the long, cantilevered end of the manifold so that it shouldn't be affected by the weight of the carburetor. Until I get the bronze castings for the replacement intake flanges I can't proceed on this but it is at the point where I can work on the exhaust manifold without worrying if I'm putting two parts in the same space.

 

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Because the critical element of the exhaust is the location of the down-pipe from the manifold, I'm starting there. The first step was making a really robust clamp that will hold the down-pipe in place, both to allow me to work on the manifold itself and, when it is done, support the manifold. I took the large steel ring I'd made earlier and milled a flat on one side. This will be the back of the clamp and gives me a reference surface for the next machining operatons.

 

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I then used my antique B&S height gauge to scribe a line precisely through the center of the hole... it is a 2" hole although the finished size will be 2-1/4".

 

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Using the flat as a reference point, I milled two 1/2" holes for screws and center drilled them.

 

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With that done, I moved over to the drill press and drilled the holes through. I forget the size but it's the correct size to be threaded 5/16-18.

 

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The ring was then cut into two halves with a slitting saw - the first time I've successfully slit steel.

 

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It worked pretty well. Of course, the holes line up perfectly because they were drilled together.

 

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The next step was to tap the holes for the back half of the clamp. The flat I milled gave me the needed reference surface to get these perfectly straight.

 

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Then the front half of the cap was drilled 1/64 over 5/16 and counterbored to accept the screw heads.

 

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I was now able to reattach the parts but, because of the material removed by the saw, the ID and OD are no longer round.

 

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To fix this, I set it up in the mill and bored the center to the finished size.

 

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Now that the center is round, I'll do the outside but I'd forgotten I don't have the proper expanding arbor so I finished the day starting on a "quickie" tool to hold the ring while I turn it. I also have to fix that hole I drilled in the bottom. I should have followed my own advice and quit when I was tired... I drilled the wrong size hole and didn't center it properly. I've thought of a way to fix it but, like so many things, it will take a little extra work.

 

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Edited by JV Puleo
typo & grammar (see edit history)
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Joe,

What is the chosen material for the exhaust tube?  What is the temp. rating for the silver solder you are using?

Al

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I am using a piece of stainless steel exhaust tubing for the bit that will attach to the manifold - mostly because when it is done I never want to have to deal with it again. Also, it will need a ring brazed to one end so it isn't the sort of piece that can be easily replaced by anyone. As far as the solder is concerned, so far I've used plain 50/50 lead/tin - melting temp around 400 degrees F. There isn't any reason why an intake manifold should get anywhere near that hot. Years ago I read a description of the tubing shop at RR where the Silver Ghost manifolds were made that included a reference to a large gas brazier that kept the many different soldering irons hot... implying that they were using soft solder as well. I think a lot has to do with the interface between the parts. Where I had to solder some of my pieces to a section of tube in order to machine them, they went together easily with MAP gas but I had to use the acetylene torch to take them apart. I may use something different for the connection between the flanges and the 90-degree elbows since those are attached to the jugs and, if the manifold gets hot at all, that will be the spot. If the engine gets hot enough to melt the solder, something else will be drastically wrong.

Edited by JV Puleo (see edit history)

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This morning I turned up a piece of aluminum with the OD of the exhaust pipe to use as a fixture for turning the OD of the clamp.

 

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It worked quite well... in fact, better than I had expected. The clamp will have a very slight "pinch" on the tubing which is exactly what I want. Here's the piece with the OD and ID concentric.

 

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In case you are wondering about this... I am reasonably certain that the car originally had a similar clamp. There two bosses on the crankcase arm in exactly the correct position to secure it. Of course, I've never seen one but it makes sense. As I think I've said, when I bought the car, three of the four ears on the exhaust flanges were broken off. This would be the likely result of running it without this clamp to support the manifold, especially if it was shaking badly. Judging from some of the surviving engine parts, that is virtually certain.

 

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I also fixed the hole I'd drilled incorrectly. It is in the center now. I will be making a special stud that will press into this hole and be secured with a tapered pin.

 

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Edited by JV Puleo (see edit history)

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Joe , Great looking work! I wish you lived closer! Im anxious to see this power plant  totally assembled? Just think 100 years from now the experts will be saying" What the hell is it?? What have we found?? It must be a factory prototype!"  Your friend, Mike West

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Hello Joe,

DO you have an idea what type carb. you will be using on the Mitchell?  It looks like, as in all cases, space is going to be very tight to fit any carb.?

Regards,

Alan

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A Stromberg M3. I have 3 of them, hoping to have enough parts to make one good. There is plenty of room but I am going to mount it with the air intake facing forward. That will give me room to include an air cleaner.

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Because the mill was set up with the vise, I decided to make the bracket that will bolt to the crankcase and support the exhaust clamp.

 

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Here it is finished. I've made this to be slightly adjustable. The exhaust manifold will have 8 or 9 parts, all welded or brazed together so I can't be absolutely certain everything will line up perfectly when it is done... some adjustment should compensate for that. This is really reverse engineering gone mad.

 

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And on the crankcase where it lines up with the two bosses that I believe were intended for this purpose.

 

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After that was done I milled 1/2" round reliefs into the upper and lower faces of the clamp. My guess is that, in period, they would have used a casting so this will approximate that to a small degree. The plan is to have the manifold ceramic coated when it is done and I will probably have these parts done at the same time. I don't like painting machined parts but exposed to the heat of the exhaust they are certain to rust.

 

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Here are the two parts finished. Tomorrow I'll make the stud that attached them.

 

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Here is the stud that will connect the parts.

 

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Threaded and the end turned to be a press fit in the ring.

 

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After it was pressed in, I drilled and reamed for a tapered pin. When the ends are filed off, the pin is as good as invisible. I like using pins but only with parts that will never have to come apart. Unfortunately, they were cheap so Mitchell used them in all sorts of inappropriate places. The problem with them is that once seated they rust and are virtually impossible to remove.

 

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Edited by JV Puleo (see edit history)

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The exhaust bracket assembled...

 

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And mounted on the engine holding a piece of tubing.

 

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I am now going to make the threaded connection between the exhaust tubing and the manifold. This will be similar to the water connections but much larger and, of course, it has to be made of steel. I think this is A36 - a mild structural steel. It is tougher to machine than the high lead stuff I usually use but these parts will have to be welded and that material doesn't weld well.

 

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Here it is bored out to 2". The finished hole will be 2-1/4 but I've no good way to hold the piece so I'll have to finish bore it as the last step.

 

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Turned to the major diameter of the threaded portion.

 

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Nice job, your projects all carry a similar theme in the appearance so it does not come off like a hodge podge.  I am very impressed at the thought you are putting into your design and ultimately the end results.  Are you going to put a gasket under the exhaust support the is mounted to the aluminum leg of the engine?

Al

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Maybe. That part might change as the design develops. It shouldn't need one though as there will be very little transfer of heat from the tube to the aluminum arm of the crankcase. I am intending to use a crush gasket in the connection between the manifold and the exhaust tube. The consistency of design is all planned... I certainly make changes on the fly but I try to keep everything similar and within the bounds of the 1910engineering manual I'm using as a guide.

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I didn't get to work in the shop over the weekend - I went to my once-yearly car show. Once it was the high point of the season. Now, out of about 300 cars, I'd say there were maybe 6 that were interesting. There are some splendid early cars here n RI. I even know where some of them are but the owners aren't interested in being belabored with loud 50s and 60s music and a field that looks (to quote someone else) like a used car lot. I go to see some old friends but the consensus is that the time is coming when we won't bother to make the effort.

 

I turned the threaded piece in three steps - the large portion will be threaded. The middle one is the diameter of the 2-1/2 butt weld elbow and the small section goes inside the elbow to position it for welding.

 

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With that done, I threaded it 12tpi. This is a fairly fine thread for this diameter and is also the one that was most commonly used in period. A lot of early parts were made with a 12tpi thread - I suspect because it is adequate for everything from 1/2" to 3-1/2". Being an even number divisible by 4, it works well with a threading dial. The red dychem is there because I like to scratch the surface to make sure it is set correctly.

 

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Here is the threaded part...

 

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And inserted into the end of one of the elbows. The angles and clearances for the other parts still need a bit of work and I may opt to use the smaller elbow, with a tighter curve.

 

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Tomorrow I'll make the nut that screws on to this.

Edited by JV Puleo (see edit history)

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The next step was to make the nut that screws on to the manifold union. I probably should have made this from a piece of heavy wall tubing. It would have saved some work but I had this piece and it is the right material. The first step was to put a hole in the center, face it on both sides and turn the OD.

 

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In order to bore it, I had to put it in the big chuck. The aluminum bars behind the piece are positioning it parallel to the face of the chuck. Because the hole I will be boring is larger than the hole in the center of the chuck it is necessary to have clearance behind it so I can see the boring bar when it comes through. This system isn't perfect. The piece is always a tiny bit off so when it was locked up and dialed in I took a very light cut off the fact to make sure the hole would be perpendicular to the face.

 

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It was then bored out to the minor diameter of the threaded union.

 

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And threaded. This material does not thread all that well so I took very small cuts and repeated spring cuts. It came out smoother than I had expected but it was a tedious job.

 

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I was taking cuts of only .002 as I got closer to the finished size. The goal was to get large enough so that the male threaded part would go in with only hand pressure. I succeeded in doing that although there were the inevitable burrs that made it stick slightly as I screwed it in. I then put a little grinding paste on the threads and worked it back an forth to de-burr it. I'm quite pleased with how this worked. At no point was it extremely difficult to turn and the finished part works smoothly.

 

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The last step was to cut the male threaded portion down to 1/2" (it had been 3/4"). It doesn't need all that. With a thread of 12tpi, it still has 6 turns to tighten it up.

 

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Edited by JV Puleo (see edit history)
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The next step was to make the end of the nut. This is a piece of 1/4" A36 steel... one of 6 steel discs I bought on ebay a few weeks ago. I need one of them for the oil pump and I'm using another for this part. I put a 1" hole roughly in the center and turned it on a stub arbor. These are usually used on the milling machine to hold slitting saws or cutters. In this case, because the plate is only 1/4" thick it would be impossible to use the expanding arbor. There is just no way of getting it to run perfectly straight. In order to keep it from slipping, because the only pressure holding it solid is that created by the nut, I put a keyway in it.

 

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When I had it turned down to the correct diameter, I threaded it. This stuff does not thread smoothly and I had a lot of trouble with this part of the job. Fortunately, the thread is only there to keep it in place.

 

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Here it is screwed in. I made no effort to deburr this piece as it will never move after it is brazed in place.

 

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The center will be bored out for a clearance fit around a piece of 2-1/4" exhaust tubing.

 

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I then brazed the end plate to the ring of the nut, concentrating on the interface between the two parts. I also left the end plate about .050 proud of the back of the ring.

 

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While it was cooling off, I put the male half of the coupling back in the lathe and indicated it.

 

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When it was cool enough to handle, I screwed the nut onto the male piece and faced off the braze. I took it down to about .010 above the edge of the ring. This removed all of the braze in the center and I was able to precisely locate the line where the two parts meet. I grooved the line with a "V" shaped cutter and brazed it again. When that cooled off, I turned it until the entire face was clean except the little braze line. Since the purpose of the brazing is to keep the back plate from turning - it's held in place by the threads, I'm confident nothing will ever move. My only criticism is that I didn't make a perfect braze the 2nd time. There are two or three little flaws in it but enough is enough.

 

I then bored it out for a clearance fit on 2.25" exhaust tubing.

 

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Since the male part was all indicated, I now counterbored it for the exhaust tube. This will allow the tubing to slide up into the fitting.

 

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With the nut screwed on to the male portion, I took it over to the mill and made the slots for the hook spanner.

 

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Here is the finished part. Unfortunately, it's too reflective to get a good picture with the cheap "point & shoot" camera I keep in the shop.

 

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And, set up on the engine. I now know that I will have to use the short bend for the manifold and that this 25-degree bend is probably too much. I'll get a 15-degree bend. I still have some adjustment room to move the pipe away from the engine but, as it is, it is too close to the water connections. This was why I had to do all three of these jobs together. It was inevitable that I'd run into some place where things had to be modified to fit - I'm just thankful it is this simple to rectify.

 

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