Author Topic: 1909 Mercedes Aero Engine  (Read 19717 times)

Offline Craig DeShong

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Re: 1909 Mercedes Aero Engine
« Reply #225 on: July 12, 2019, 12:41:41 AM »
The model is shaping up nicely, looks great  :ThumbsUp:
Craig

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #226 on: July 12, 2019, 08:38:10 PM »
Yes, Lars. These castings really save some time. I was pondering over how I was going to make them!

Thanks Craig. I really must find some time to go back in the shed and finish the job. I have a piece of Delrin for the distributor and the rest just needs assembling. Unfortunately, life is getting in the way!

Steve   :)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #227 on: August 03, 2019, 08:49:45 AM »
Greetings!

This summer has been a bit busy. However, the plumber has gone, the house is drying out and my books are OK so all is well and I am back in the shed. I am now in the process of final assembly.

I have been pondering my cylinders and the tightness at the top of the stroke. they weren't right so I finally decided to bite the bullet and lap them. First job was to make the lap so I took Jo's advice and used a taper pin reamer to machine the bore of the lap. I then set the reamer up in the chuck to allow me to set the topslide over at the right angle.



The mandrel was just a bit of bar out of the drawer.



I tapped the lap onto the taper and machined it to size before removing it and cutting some slots with the hacksaw. One went right through of course.





I then loaded it with 'Autosol' metal polish and held the block whilst rotating the lap. as the lap eased off, I just tapped it up the taper a bit more for another bite. The bores come up surprisingly quickly so there was another job done. By the way, I took the picture with the lathe stationary as two hands and careful concentration were required to avoid disaster!



My experience of old engines suggests that the blocks should be held down with studs rather than bolts so I made some up. A tedious job but it worked out OK.





Time for the camshaft. Tappets in first and then wangle the camshaft. It took some fiddling but went in the end. The end bearings were a bit of a puzzle though. If I pressed them in, then I wouldn't be able to get the camshaft out again. However, if they were loose then they would move in service. I decided to put some locking screws into the side of the crank case to secure them.





Time to drop the crank in. Each bearing has an anti-rotation peg to locate it and keep the oil holes pointing the right way. Then all was secured with the centre bearing cap.



Now the timing gears don't line up!



A quick skim off the removable camshaft bushing and all was well.



File up a square key for the propellor boss.



The camshaft gear wheel is intended to have a 3mm grub screw to secure it. My workshop is imperial so I tapped it 5BA. However, I then found that grub screws are made in 2, 4 and 6BA! I have been making do with a slotted screw but it didn't look right. A hex head didn't look right either so I have made up a square head locking screw from silver steel.



It is still a bit 'heavy' but not so obviously wrong.



Finally, this week, some sump plugs.



Coming on!



The blocks are in the paint shop at the moment so time to finish the sump and the oil tray.

It is good to be back!

Steve :)




Offline Roger B

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Re: 1909 Mercedes Aero Engine
« Reply #228 on: August 03, 2019, 11:08:37 AM »
That's some good progress  :praise2:  :wine1:
Best regards

Roger

Offline stevehuckss396

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Re: 1909 Mercedes Aero Engine
« Reply #229 on: August 03, 2019, 11:26:53 AM »
That Looks like some top notch work there. Do you plan to remove some more metal off the crankshaft? just curious.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #230 on: August 03, 2019, 01:49:00 PM »
Thanks Chaps.

My original plan was to build it exactly to drawing apart from the metric fasteners, so the crank will stay as it is. However, if I had drawn it myself, it would be much more slender and more representative of the original. I may do that yet if this one doesn't survive!

Steve  :)

Online Jo

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Re: 1909 Mercedes Aero Engine
« Reply #231 on: August 03, 2019, 03:12:41 PM »
My experience of old engines suggests that the blocks should be held down with studs rather than bolts so I made some up. A tedious job but it worked out OK.
..
It is good to be back!

Steve :)

Real Studs  :Love: Have you thought of using a 1/8 whit grubscrew instead of a 5BA? Much easier to come by. I normally use 1/8 whit in place of 5BA for conrod Allen screws they are dirt cheap rather than rare as rocking horse do-dahs  ::)

Nice to see you in the workshop, I thought it was lorry weather  :noidea:

Jo
Usus est optimum magister

Online Vixen

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Re: 1909 Mercedes Aero Engine
« Reply #232 on: August 03, 2019, 07:26:33 PM »
Nice work Steve.  :ThumbsUp: :ThumbsUp:

It's always amazing how much work and time is consumed getting those last little bits made and then made to fit, when all you wanted to do is just to bolt the engine together.

What are your plans for the next engine?

Mike
It is the journey that matters, not the destination

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #233 on: August 03, 2019, 10:17:40 PM »

Quite r.ight Mike. It takes ages and you keep finding other little challenges! Like today. I thought I would just screw in the oil tray. I did that but found that the big ends just scrape it at BDC. I can get around that but the actual function of it now puzzles me.



As you can see, there are what Heinz calls a levelling hole and an overflow. These cannot, however, be doing anything useful in this engine. If the engine had, as originally built, a forced lubrication system then they would be good as the oil leaving the big ends would fill the tray, overflow into the sump and be recirculated. However, this is a splash lubricated engine. There is no pump to top up the tray so the oil level of the engine has to be set at the right height when filling and the sump is just dead volume. The centre divider means that half of the engine could have a low oil level and there is no way of telling what is in the engine. On thinking this through, I have decided to do away with the tray and fit a level plug. That way, I can tell when the engine is full and the full volume of oil can be used.



For a bit of light relief, I decided to fit the pump and promptly tripped over the next challenge. When mounted in this position, the pump outlet interferes with the contact breaker and distributor on the end of the camshaft. The picture on the drawing booklet shows the engine without distributor fitted and Lars is running on glow plugs and has also avoided the problem. One to ponder for a few days.



After that, the dummy oil drain pipes were easy!



I have started lapping valves and have fitted the first valve spring.



How gas tight would you expect the valves to be? If I blow up the bore, I can feel the air escaping very slowly so they certainly aren't perfect. I expect that compression would hold for a couple of seconds if the crank were to be turned to TDC. What would you expect?

More valve lapping tomorrow!

Steve  :)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #234 on: August 03, 2019, 10:21:39 PM »
Thanks for the grubscrew thoughts, Jo. The main problem was that I had tapped the hole before identifying the grub screw. I just thought I would be able to get them!

When were hex grub-screws first used? I have never found any on my 100 year old engines so I don't think they would be right on this model anyway. I guess that the timing gear should be secured on a taper with key and a large nut on the end of the camshaft. Too late to do anything about them now!

Steve  :)

Offline Roger B

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Re: 1909 Mercedes Aero Engine
« Reply #235 on: August 04, 2019, 08:18:28 AM »
The valves should be tight with breath pressure. Are you sure that the leak is past the valves and not via the spark plug thread or valve cage (if it has them)?
Best regards

Roger

Online fumopuc

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Re: 1909 Mercedes Aero Engine
« Reply #236 on: August 04, 2019, 08:22:56 AM »
Hi Steve, nice progress. I am also just fiddling around with a gear train.
Kind Regards
Achim

Online Jasonb

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Re: 1909 Mercedes Aero Engine
« Reply #237 on: August 04, 2019, 01:31:42 PM »
The oil tray as it is I can't see it doing a lot. usually they have end plates so that once the oil has been flung out it will only flow back into the tray at a slow rate through the overflow hole. Have a look at the Puma thread where I posted a picture of one that works.

The other trick with grub screws is to use a socket one for ease and strength then when the engine is set up and running OK make a small square head to screw onto the exposed end.


Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #238 on: August 05, 2019, 05:53:28 PM »
Well, that was a tedious day! I spent it lapping in the valves. Thank you for your guidance, Roger. That encouraged me to persist! I started off by greasing both valves and fitting them along with a spark plug. That sealed them up nicely and allowed me to see if there were any leaks around the cage or liner. Then I took one out and cleaned it and blew again to see how bad it was. I lapped it using a screwdriver and fine valve grinding paste followed by Autosol metal polish until it was tight. (the screwdriver slot in the valve head certainly paid off). Once I was satisfied, I fitted the spring and did the second one. All very successful but dull in the extreme!

I had to fit the blocks to see what it was going to look like.





Looking promising.

Thank you for your thoughts on grub screws, Jason, and your views on oil trays. I like the idea of allowing the oil to flow slowly back in but I don't think it will work well here as there is insufficient reservoir space around the tray. One for the future, perhaps.

Rockers next!

Steve  :)

Offline Johnmcc69

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Re: 1909 Mercedes Aero Engine
« Reply #239 on: August 05, 2019, 09:13:35 PM »
 :ThumbsUp:
 Beautiful!

 John