Author Topic: McDonald Imperial Super Diesel Crude Oil Engine  (Read 15929 times)

cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #45 on: August 10, 2020, 06:53:39 AM »
Going to be attacking the bore with a large hone soon and today the head came back with the new valve guides fitted and reamed, new stainless steel valves machined to suit and the seats re-made so at least this is ready to be fitted after the bore and piston are in.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #46 on: August 12, 2020, 07:02:08 AM »
Here is the head ready to fit some springs but I have to drill the valve stems to fit a pin to hold the cups in place that hold the springs under tension. I do not have the original horseshoe clips so a couple of pins will work well.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #47 on: September 05, 2020, 06:50:33 AM »
At last I got back to this project this afternoon. I have borrow a large honer and it certainly has cleaned up the rusty surface very well but after a fairly long time I still cannot get the piston with no rings to slide up the bore. The top goes in with no problems but the further I slide it the tighter it gets and will only slide in as far as the bottom of the piston skirt.
This got me thinking, yep hard to believe, that maybe the piston is out of shape and not the bore as I was thinking. I had the piston off the conrod and put it in the lathe and using a dial indicator got some out of round numbers on the OD of the piston but from top to bottom it changed a lot and was messing me up.
So I engaged the grey matter again and used my digit calipers to measure the OD as far as it could reach over the skirt measuring from the side. and did this at 3 different points, top, middle and bottom.
Not sure if my calipers reached over the complete OD of the piston but with the calipers pushed all the way on then closed the gap and locked the calipers it gave the following readings.
Top -      87.77mm
Middle -  88.21mm
Bottom - 88.40mm
This meant that the piston got wider the further down I measured it and by a total of 0.63mm and this to me would indicate that the piston and not the bore is at fault.
Happy to hear any and all comments on this tricky bastard.
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mikenash

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #48 on: September 05, 2020, 01:14:54 PM »
Y’know, if the piston is most of a mm different in diameter from place to place - it seems to me that if you held a straight-edge along it in various places there would be enough for the straight-edge to “rock” visibly?  Cheers

cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #49 on: September 05, 2020, 01:47:58 PM »
Cheers Mike, the taper is on the piston itself and not the bore. I have no way of measuring the bore but was told to use a length of stiff fencing wire cut to size and use it as a gauge. Tomorrow I will know ,ore, I hope.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #50 on: September 19, 2020, 06:56:29 AM »
Back to the Mac and trying to sort what exactly is out of round. The piston is 0.009" out of round for certain and after putting on some "blue" and fitting the piston into the bore to see what part rubbed it hits the bore both top and bottom.
You can see on the skirt of the piston where the 'blue' is untouched and where it is rubbed smooth. What clearance should there be between the bore and piston on a 3.500" bore?
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #51 on: September 20, 2020, 07:40:17 AM »
And the winner is.....cobbadog! I got the bastard!
There was definitely 2 different issues, the bore for what ever reason was undersized at the bottom end and believe or not there was a bump on the piston skirt. So with a long time honing, washing it out and then checking it was time to go to the lathe.
As suggested I set it up using the dial indicator and this time with the piston top in the chuck and at that point it ran true. As I went down the skirt things were good but then I rotated the chuck and presto a lump on the skirt. So no amount of honing would fix this issue and would make the bore completely the wrong size if I didn't machine the piston. So yes something must have been dropped onto it and caused this problem. Now I have the same clearance top and bottom and that is 0.010".
In the pics you can see the hone in position ready to have the drill connected to it which is a socket on an extension with a slot to engage the small lugs to drive it around. Liberal amounts of kero was used and it certainly hooked into cleaning things up and it works far better than the spring loaded hones.
You can see the high spot on the skirt and as I took 0.01mm off at a time it slowly progressed towards the oil ring land then from there up all was good.
A picture of the Australian made Somers brand rigid hone.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #52 on: September 21, 2020, 07:42:22 AM »
Got the rings onto the piston and gapped them using the cut off wheel of my grinder. (that will be a talking point).
Fitted the piston then the crank into place and connected the big end to the conrod and then to the crank. Made a new gasket out of 1.5mm paper for the side cover that houses the other crank main, fitted a new oil seal and then put the cover on and tightened it. The rings a have a good hold of the bore but once I have it moving I can move it with a struggle by turning the crank by hand. Once the flywheels are on it will be a lot easier.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #53 on: September 21, 2020, 12:12:31 PM »
Thanks Glort, I too am anxious to hear the mongrel run again. Not sure at what level it will run at but the aim is for it to be loud and dribbling oil somewhere and blowing smoke. :)
I have a list of things that might be wrong in what I have done and the cam gear rebuild done to a guess shape is high on the list of things. The spring tension for the needle in the injector is another. Tomorrow I want to make some caps for the valves and with a special design to do the job so will take some pics of the design. It is a combination of the originals and something new.
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mike90045

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #54 on: September 22, 2020, 08:09:15 AM »
Are you pre-lubing parts as you assemble ?   Either with engine oil or with assembly lube ?

https://rxmechanic.com/engine-assembly-lube/

Q. How Do You Lube a Cylinder?
     When applying lube on a cylinder, start by cleaning the piston by wiping off the earlier used lubricant from the piston. This is after raising its seat to the maximum. If the cylinder has a bellow or a cover, access the piston by pushing the cover-up. The piston will have some exposed parts, and that is where you apply the assembly lube. After that, distribute the lube to other parts of the piston by lowering, raising, and rotating the seat. Go through this video to see how it is done:
https://www.youtube.com/watch?v=Z8z90fbpeB8&feature=youtu.be

cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #55 on: September 22, 2020, 12:12:42 PM »
A lot of the things you do to the 2 strokes is a good thing and certainly won't harm anything. I don't over oil the fuel mix but I always use Premium fuel and quality 2 stroke oil and not the old sae30 mixed into the old standard fuel.
My very first Victa a Model 2, I have had since 1967 and threw the engine into a home made mini bike and rode that around the streets of Sydney for a couple of years before putting it back into the mower frame and continued to use it to mow the grass. When I turned 21 I had to rebuild the engine and went out of my way to avoid the 'chromium' rings as they wear the bore too quick. Since that full rebuild the only thing I have done over the years of ongoing use are a number of head gaskets and spark plugs, that's it. It still starts first pull on the rope and cuts the grass and throws it to buggery. Since that engine I have lost count of Victa engines I have repaired and rebuilt and still have many more to do one day.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #56 on: September 22, 2020, 01:43:00 PM »
Corn Flake packets was my choice of cardboard for the gasket and the head got a quick rub on the cement step, high tech stuff.
As for something to attach to the Mac, I do have a couple of water pumps, no generators here and at one stage I was going to make a Prony Brake for the big Lister and this may still be an option down the track. Just for now I want it to make noise, leak oil and blow smoke.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #57 on: October 01, 2020, 07:00:40 AM »
This is the head sorted and the new valve colletts I made and you can see an original "C" clip as a comparison.
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cobbadog

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #58 on: October 01, 2020, 07:05:05 AM »
Next I have started the assembly of all the driven gears and stopped when I found I had lost a small woodruff key which I will buy tomorrow. I also made a flat plate to hold the governor gear on the shaft. The gear does have a small pin that sticks out but would hit the side cover if I didn't put something here to stop it moving. Made a new side cover gasket and you can see what I had to do to the speedi-sleeve that I fitted in place before fitting the crankshaft driven gear. So it had to be hit with a chisel and removed, gear fitted and new sleeve ready to go back on soon.
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mikenash

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Re: McDonald Imperial Super Diesel Crude Oil Engine
« Reply #59 on: October 01, 2020, 07:51:05 AM »
How have you found those speedi-sleeves. My results with them have been “mixed” at best. But I may just be clumsy :(