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McDonald Imperial Super-Diesel Engine

cobbadog

Registered
Hi hceeB,
I will have a look at it but know nothing of it at the moment. However tomorrow I will take the head with me back into town and see if I can get him to accurately measure the guides and I am looking at getting some over sized valves made, this may be the simplest and easiest way to go.
Having endured the day without power because they replaced a transformer down the bottom of the street I could not do the jobs I wanted to do but did get to shuffle a heap of curtaining fabric around in Dee's work room. So when I finally got to play mode I had a go at removing the needle from the stem after being in the electrolysis tank for a couple of days. It did come out sparkling clean but obviously still a lot of carbon on the inside. I have easy access to the bottom of the needle via a hole where the fuel would run into the cup, also can get a good hold on the top of the needle but it is not budging yet.
In the McDonald hand book of instructions it does mention a few times to use 'kero' to clean the fuel system parts in. Why this is suggested rather than clean diesel is a mystery to me. So it is soaking in some kero at the moment. I am also now eyeing up my ultrasonic tank as I can actually touch it now some fabric is gone. so find a plastic jar and some petrol and spark it up, literally not physically.20200614_092246.jpg20200614_114514.jpg
 

Scotty 2

Registered
Cobba, nothing to do with freezing and heating etc but back to your valve guides, how would nodular cast iron go? If you google it the properties re wear etc are very good, there is plenty of it lying around as Briggs and Stratton cranks are made from it and machines very easily.
Crikey. How big are Briggs cranks? You'd need at least an inch and a 1/4 OD for the guide wouldn't you Cobba?
 

cobbadog

Registered
Hi Scotty,
The McDonald valve guides are an odd shape to say the least. With that step in the top to hold the valve spring in place, the wide shoulder to stop it going down the hole in the head then they differ in length as to how far they protrude into the port area.
The widest point they are around 28mm on that shoulder. So today I found a supplier of the cast iron and it will be on its way soon. Spoke to the engine bloke today and he removed both guides so they can be copied and also spoke to Bills Motor works about the supply of some new valves. Bill was out doing a walk-about and he will get back to me soon, I hope along with some good news about the rings for the engine too. So maybe some progress is about to happen again.
Back to that needle soaking in kero. This seems to do nothing and a very generous hit with carby cleaner also has not shifted anything so far. So the plastic jar of petrol and into the ultrasonic tank looks to be the next step.
 

muzzery

Registered
Cobba, that’s a bit interesting about the kero, I remember being told not to use kero on moving parts as it is an abrasive. Mainly talking about vehicle brakes assemblies.
 

cobbadog

Registered
I've heard the same too Muz but in the hand book this is what it says to use. Having said that this info goes back a long time and we all know how views can change over time.
Eating too much bacon caused cancer, same for eating butter all things that we now know is not necessarily true, moderation on most things is ok. If nothing else I have the refreshing smell of keroo wofting along my bench at the moment.
A bit over a week ago I contacted Don Reid about the gib keys and it is good to talk to him again and he asked for a few days to go looking. So I contacted him again today and it is still on his list of things to do, which is a good thing. Valves and rings are still an unknown thing as yet but will try Bill again tomorrow.
 

eddie bedwell

Registered
Hi Team,
Yes, Kero is essentially dry and so can cause galling when precision parts are slid over one an other--ie, rolling element bearings like ball races etc. after they have been cleaned in raw Kero.

Back when I was an apprentice, in the early 1960's at the local Cat Dealer, I used to have to put around a half a gallon of oil to 4 gallons of Kero into our cleaning tray so as to leave an oily film on the parts we washed to inhibit rust during storage while waiting for parts.
Also easier on the skin.
Just my experience and yours may vary.
Cheers,
Eddie B.
 

cobbadog

Registered
This is the new fuel tank that should be bombproof against any blow back from the injector. Just adds more weight to the transporter but should work well.
Also this is the condition of the new piece of 30mm wide flat bar iron acting as the anode in the bath tub. This is just 1 days worth of crud and the amount of pitting under all that stuff is amazing.
 

Attachments

isandian

Registered
I was alseep at the wheel! I have got the fuel cup off the end of the housing using a good whack with a hammer on an anvil or similar. They are much worse if stuck down the hole in the head - mighty hard to dislodge. On a couple of F or FF engines, I made a tool with a ramp end after fighting with the first one like you have, made the tool and problem solved.
 

cobbadog

Registered
Cam gear is back and linished to what I think is the correct profile. At last the needle is out of the tube after a very hot episode with the big bunsen burner. The needle came out a little bent so I did straighten it but I do have the other needle to use if needed. Good news with the valves and rings and the valves should be confirmed tomorrow with luck.
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cobbadog

Registered
Got a little bit done today. I used some valve grinding paste both coarse and fine to re-seat the needle by hand and it now has a lovely shiny taper all the way around. This, I hope will minimise any compression blow back. I will pick up some copper washers (gaskets) tomorrow hopefully while driving around for work along with a new compression spring for the needle. This one looked ok but during the electrolysis process it cleaned up the rust very well and made the gauge of the wire too thin and it broke. I don't expect this to be hard to find and replace. (foot in mouth disease possibly coming on).
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cobbadog

Registered
Yes Ian, in the hand book they warn you about removing the injector from the head and that it must be done by putting a lever inside the combustion chamber under the fuel cup and lifting from that way. Any other way and that causes the injector body to break and that is what a qualified mechanic did to the original injector for this engine.
 

cobbadog

Registered
Assembled the injector today with the new spring on the needle, new copper crush washer that has been annealed to make sure of a good seat plus the roughly made grub screw which works a treat. The grub screw does not hold the cup in place but rather directs the spray into the combustion chamber inside the head then on top of the piston. When the injector is bolted down this is what seals the cup against both copper washers as there is another one to be fitted on the outside of the cup and sits down against the head. That is the lump of cast iron ready for valve guides and I nearly have the valves sorted, I hope.
Something I discovered when assembling the injector is that it works opposite to how I though it would. Once the injector body was assembled it was holding the needle in the closed position and I stripped it again trying to work out what was wrong. Then the penny dropped and the top of the injector is lifted to open the needle to allow fuel inside. Well I hope that is how it works.
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asw20

Registered
When you get it together on the engine, you may wonder if you did something wrong when the injector barely moves even on full governor. Fear not; the thing is only lifted maybe 20 thou for full blast. While running, a 10 thou feeler gauge slipped under the injector lifter will have it throttling up smartly.

Jarrod.
 

Darryl

Registered
Cobba, that looks like a pretty strong spring on the needle. All good as long as the the top spring over rides it plus some.The top spring not only has to be able to over ride the needle spring but have enough up it’s sleeve to hold back the explosion.
 

cobbadog

Registered
I was thinking that when I was fitting it. There was another spring a gauge lighter available and it is an easy one to replace now the needle is free and can be removed without removing the injector from the head.

The spring above this is also a real thick bugga and takes a bit to lift it up.
Is this the same on similar model engines please?

I also started roughing out the first of the valve guides and stopped well before the final sizes. I think I will wait until I get the ehad back home here to keep machining them up.
 
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cobbadog

Registered
Good news today about the valves. The ones he has will fit so I have ordered them and asked if he would send the valves and the rings set once they arrive. He confirmed that the rings for the McDonald did not make the last order but they are in production now in N.Z. so once that order is complete it will float across "the ditch" and come and join the fun here.
 

isandian

Registered
For a recent project, they had 4.150" diameter rings available off the shelf in three different widths, but had to get 3.500" diameter ones made. Maybe the 4.150" ones had been on the shelf a long time - hardly a popular size I suppose.
 

cobbadog

Registered
There was a run on 3.5" Od by 1/4" rings. Apparently another slow moving size until I wanted a set. At least I am happy to know the parts will be arriving soon enough. Starting to get impatient even knowing I have what I need in theory.
 

isandian

Registered
There was a run on 3.5" Od by 1/4" rings. Apparently another slow moving size until I wanted a set. At least I am happy to know the parts will be arriving soon enough. Starting to get impatient even knowing I have what I need in theory.
We needed 3.500" x .312" (5/16") and settled for 2 per groove of .156" (5/32"). Still had to be made.
 

cobbadog

Registered
I did read somewhere that is an accepted practise to fit 2 rings per groove to do the job. Possibly better than using a single ring as you would offset the ring gap in each groove so there would be none from top to bottom.
Today I started to make a list of possible "stuff ups" under a far more appropriate name that I understand but not accepted in print on any forum.
So far I have 2 items, cam profile and that spring on the needle. I think this will be of help if it does not want to make a noise and leak oil and smoke too.
 

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