Author Topic: McDonald Imperial Super Diesel  (Read 4641 times)

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #90 on: 16 June, 2020, 02:47:35 pm »
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.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #91 on: 17 June, 2020, 02:42:25 pm »
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.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #92 on: 18 June, 2020, 04:07:20 pm »
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).
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #93 on: 20 June, 2020, 04:17:36 pm »
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.
Cheers, John & Dee. Coopernook. NSW.

asw120

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Re: McDonald Imperial Super Diesel
« Reply #94 on: 20 June, 2020, 05:10:43 pm »
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.

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #95 on: 20 June, 2020, 09:43:51 pm »
Thanks Jarrod for confirming my theory about its operation. It threw me at first but thought about it and then the penny dropped, at last.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #96 on: 22 June, 2020, 04:06:17 pm »
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.
Cheers, John & Dee. Coopernook. NSW.

cobbadog

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Re: McDonald Imperial Super Diesel
« Reply #97 on: 26 June, 2020, 03:41:13 pm »
Took the advise to change the spring on the needle which was a gauge heavier than the original. So I fitted the smaller spring today and cut out the new cork gasket for the water hopper.
Cheers, John & Dee. Coopernook. NSW.