hummermark Posted September 10, 2011 Share Posted September 10, 2011 Having got the Achilles I thought/hoped it would be a straight forward job getting the engines running as they looked clean, were full of anti-freeze and had good clean oil, but this wasn’t to be the case. From what I can gather it was driven and then parked up for 35 years. I first needed to turn each engine over by hand, I needed the clutches to disengage but they were both seized. So whilst the engines were in situ I removed the transfer case and both clutches, I had to make an inch drive adaptor to go on the end of the crank shaft, removed the injectors, filled the bores with thin oil and primed the oil system with a 24 volt oil pump. The driver’s side engine turned over with a three foot breaker bar with one (bigger than average) person leaning on it, so I thought things were looking good. How wrong I was! The passenger side engine wouldn’t budge so we added a 10 foot scaffolding pole onto the breaker bar, had one person pulling and one person pushing – still no movement. So very reluctantly I decided I would have to remove the engine pack. I have posted a few pictures of when I removed the engine pack and a short YouTube video. Quote Link to comment Share on other sites More sharing options...
hummermark Posted September 10, 2011 Author Share Posted September 10, 2011 (edited) I got the engine pack home and then had to make an engine stand for the twin pack, and one high enough to enable me to work underneath the engine comfortably. I also built it on wheels to move it around the garage if need be. We managed to rock the engine free with a 15ft pole and two of us swinging on it. When turning the engine it would lock up in one place and then it would need turning backwards. So the engine pack is now in workshop for a rebuild. Head, sump and a gaggle of pistons Corrosion in the bottom of the sump where condensation built up over the years Cylinder liner removal tool in situ Liner removal tool, still connected to old liner, new liner sitting beside it Old liner has the round holes, new one has elongated holes giving a bigger breathing area. The stamp on the left cylinder in the pciture (the new one) is not a random stamp. If it is below the cylinder lip at the top it is slightly smaller in diameter, if it is above the breathing area then is is slightly bigger and if it is where shown in the picture it is again slightly bigger. The liners should be a hand push fit into the block but not so they fall under their own weight. Unfortunately the original is unmarked so I had to try a couple of liners to get the right fits, luckily for me a company lent me a few to try. Liner tool in all its glory without a liner New higher compression pistons, it has a piston ring near the crown compared to the old takeouts. Piston installation tool (in blue), it works like a funnel and the pistons must be inserted for the bottom of the liner and then the liner and piston installed into the engine this is due to sharp edge on the oil control rings. This picture shows the shims that you have to put under the liners so the liner stands 2-4 thou prod of the block. This is the old supercharger rotors showing the corrosion This is the new liner in the engine but the top of the breathing slots are obscured by the block. Apparently the newer blocks have a larger opening so if you have a 1940’s 6-71 and use new liners you have to live with the overlap. End cover off of the supercharger Corrosion in the supercharger casing Old and new supercharger. If you look at the new one, there are lugs at the top so that the supercharger can hang from the block. The 1940’s version is a continuous lug. This shows the continuous lug on the 1940's supercharger body. The engine locked up because of a tooth had broken off of the timing gear and stayed in the root of the meshing timing gear. I have to replace all but one timing gears. A new camshaft is needed which is currently on back order and costing £280. The liners, pistons and rings are approximately £175 per cylinder, so prices compared to modern commercials aren’t bad at all. The part numbers I am using are from an original WW2 parts book which Detroit in the UK can use, they have just been superseded to the modern components. I am sticking with the 2 valve head as I have spoken to a guy/seen his YouTube footage of his M4A2 and M10 Achilles that do just fine with a 2 valve head and don’t smoke. Both of his tanks have the later pistons, liners and injectors; I will be using the new N80 injectors in my engine. I have had both my water pumps rebuilt with the modern seal kit and will be doing a recommended mod of 8th oil tube from oil gallery to the governor bearing in the end of the supercharger nose as this suffered from lubrication. The old pistons had circlips and caps to retain the gudgeon pin, the new ones just have caps that you have to dent in, for want of a better word, just like a core plug (I prefer the circlips but I guess it’s progression). The big end bolts were nuts and split pins, now they have been replaced with self-locking nuts. I have currently ground to a halt as I am waiting for the specialist tool to concave the gudgeon pin caps. All of the rings have been filed, as it goes the compression rings did not need to be ‘gapped’ as they had 25thou which is within tolerance. The oils rings were within 3-5 thou so I had to file them to 10 thou. If anyone has any tips for the 6-71, I would be glad to hear of them! Edited September 12, 2011 by hummermark Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted September 11, 2011 Share Posted September 11, 2011 (edited) That looks like a lot of work and a lot of cost, but turn that round and you are doing all the work once, and you are doing it properly, so you should never have to look at it again. I've no experience with that engine, so nothing much to add, except that the 6-71 still seems to be a popular engine so I expect the whole process may end up being less painful than a petrol engined equivalent, and of course cheaper to run long term. Edited September 11, 2011 by Gordon_M Quote Link to comment Share on other sites More sharing options...
eddy8men Posted September 11, 2011 Share Posted September 11, 2011 excellent detailed technical thread, the sort of thing the next guy to have a crack at a detroit could use. cheers rick Quote Link to comment Share on other sites More sharing options...
RattlesnakeBob Posted September 11, 2011 Share Posted September 11, 2011 very impressive !..proper engineering that mate!. ....d'you mind saying where you found your M10 and where she'd been nesting for 35 years?? I know it's a lot of work and I don't know how you feel about all that amount of work but I know that when I'm wrist deep in a serious mess of a rebuild, I start to get proper excited as all the new bits slip together ........all I can think of is how smooth and sweet the motors gonna run and what she'll sound like.......great stuff ! Quote Link to comment Share on other sites More sharing options...
RMS Posted September 11, 2011 Share Posted September 11, 2011 (edited) Great project you got there Mark, looking forward to seeing the progress. it was nice to meet you at Tanks in Town, very impressed with the Jackson:thumbsup: Cheers Edited September 11, 2011 by RMS Quote Link to comment Share on other sites More sharing options...
ajmac Posted September 11, 2011 Share Posted September 11, 2011 Thoroughly interesting, technical threads are the ones that I enjoy the most, thanks for sharing it all, and nice to meet you, however fleetingly while I was chatting with Adrian as your M36 was loaded on the diamond T in Bois Brule. Must get my Loyd thread up to date, mind you not much progress ATM. Quote Link to comment Share on other sites More sharing options...
roy206 Posted September 12, 2011 Share Posted September 12, 2011 nice work mark. look like a deja vu too me it is a very nice engine too work on. when you need parts and can,t find them,let me know,maybee i can help you with it. roy Quote Link to comment Share on other sites More sharing options...
hummermark Posted September 12, 2011 Author Share Posted September 12, 2011 (edited) I cleaned the exhaust valves and found that most f them had heavy corrosion pitting on the stems, so I ordered a new set of exhaust valves. Apparently the older 6-71 engines had 30 degree valve seats, the 30 degree exhaust valves are no longer supplied by Detroit, so if you unless you have a source you have to have 45 degree valve seat inserts. In the background you can see the big end shells, they weren’t too bad, all of the white metal is good (I am re-shelling them anyway). Cylinder head after a clean up, cam followers were corroded in guides but I have removed and re-homed the guides. Oil pump has two scavenger pumps in it which in the wet sump engine feed the oil pump pressure side. This pump is no longer available and does not have a superseded part number from Detroit nor is just the oil pump housing of the scavenger gears. This shows the old original 80s series injector (rusty and seized) next to the new N80 injectors. As you can see from the pictures the old injector has the fuel flow and return in line and then new one has them offset this is why when you have the new N80 injectors you need to order the mod kit which has different fuel posts and fuel link pipes. I had to but the injectors outright as they would not take my original 80s series injectors in part-ex :-(. A data plate showing the Royal Canadian Electrical Mechanical Engineer rebuild which occurred in the 1950s. The original timing gears – spot the missing/ripped teeth! A supercharger from Detroit is £1200 + VAT, there is a core charge of £350 - they won't take the 1940's in part-ex though :banghead: Edited September 12, 2011 by hummermark Quote Link to comment Share on other sites More sharing options...
hummermark Posted September 12, 2011 Author Share Posted September 12, 2011 It would be nice to see before and after picutres of your nice shiny, running engines and then it would show the amount of work you have put into them! Hope mine runs as sweet as yours... nice work mark. look like a deja vu too me it is a very nice engine too work on. when you need parts and can,t find them,let me know,maybee i can help you with it. roy Quote Link to comment Share on other sites More sharing options...
Scammell4199 Posted September 12, 2011 Share Posted September 12, 2011 Fantastic work Mark, all this technical stuff is brilliant. Just goes to show that something which is seemingly in good nick on the outside has some pretty serious problems inside, just like i found on our Scammell gearbox. Keep up the good work, looking forward to seeing (and hearing) the finished product. Richard Quote Link to comment Share on other sites More sharing options...
Niels v Posted September 14, 2011 Share Posted September 14, 2011 Well your blower looks better that our yours where taken out of a mobilisation force in 1982 to and then probably driving out and left in on a training ground as an object until a couple of years ago. Quote Link to comment Share on other sites More sharing options...
supertrack Posted September 15, 2011 Share Posted September 15, 2011 thank's for pictures they are very interesting . :cheesy: Quote Link to comment Share on other sites More sharing options...
malyutkaman Posted September 15, 2011 Share Posted September 15, 2011 Love the pix of the rebuild!!! Super fun project. Not to get your hopes up but I've got a bunch of parts for early series 6-71's. NOS valves, a supercharger impeller, starter, governor, injectors, etc.... If you can't find what you are looking for closer to home let me know what you need and maybe could swap some parts or whatever. I'm always looking for parts for my BRDM2 (if you know of a supply). Hope this helps, Richard Quote Link to comment Share on other sites More sharing options...
roy206 Posted September 22, 2011 Share Posted September 22, 2011 this was our engine in beginning :-D but never mind,when they give me another one,i do it again with pleasure.nicest work too do is install the governor and line up the injectors.look out ,you has too modify the injector rack,the rack will hit the injector at full throttle,also the return spring from the rack hit the first injector.but a little grinding makes that it will go. Quote Link to comment Share on other sites More sharing options...
robin craig Posted September 23, 2011 Share Posted September 23, 2011 Nice to see all the work and care and money you are putting into it. Interesting RCEME connection. R Quote Link to comment Share on other sites More sharing options...
examech Posted February 14, 2012 Share Posted February 14, 2012 Did you have the tooling to check air tightness of the gudgeon pin "pennys?" This is a well known cause of crankcase overpressure on all Detroits and the reason for the change from circlips. Quote Link to comment Share on other sites More sharing options...
hummermark Posted February 14, 2012 Author Share Posted February 14, 2012 Hi, I did buy the rubber suction cups from Detroit for testing the air tightness gudgeon pennys, also this suction cup does the valves as well. I will be putting this on my next installment of the engine restoration when my IT secretary can be bothered (my daughter)! Mark Quote Link to comment Share on other sites More sharing options...
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