jamie meachin Posted February 18, 2015 Share Posted February 18, 2015 (edited) After some thought while restoring my halftrack, I decided to put a more modern engine in it. When I bought it it came with a Ford industrial engine which I believe there was a company in the 60's making this conversion. So what engine do I put in it? I have a friend who works at first bus and he managed to get me a Cummins 6BT that had just come out of a bus. The next task I had was to fit the halftrack gearbox to the Cummins engine. A few people suggested find the proper bell housing for the engine to suit the gearbox but I had other ideas. I work as a design and development engineer, doing 2D and 3D design as well as good old fashion manual turning, milling ect and love a good project so why not make a adaptor plate to join the halftrack gearbox the the Cummins engine? How hard can it be...? The first thing to do was find some material, luckily I had a piece of 3/4" thick plate I have had kicking about for years thinking one day it will come in handy. We flame cut it leaving about 1/4" on both the OD and ID. The next minor problem I had was it wouldn't fit on our lathe at work, so how do I overcome it? The solution, use a rotary table on the milling machine and to do this I had the make a fixture to be able to hold the plate. Edited February 18, 2015 by jamie meachin Quote Link to comment Share on other sites More sharing options...
GeePig Posted February 18, 2015 Share Posted February 18, 2015 It looks like the actual machining of the plate will be the shortest part of the project! :-D Still, I am sure that mount will come in useful again. trevor Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 18, 2015 Author Share Posted February 18, 2015 (edited) After creating a fixture, I began by machining off the OD and ID to the correct diameters I needed. The next thing was machine the front face and put a step in it for the halftrack gearbox location. The next step was to put 2 sets of holes in the plate, 1 set for the halftrack gearbox, the other for the engine. For the gearbox I drilled and tapped the holes for the use of studs when bolting on the gearbox. For the engine I drilled clearance holes for M10 thread, counter bore and countersunk the plate for the use of countersunk screws. After machining all the holes I then fitted the adaptor plate to the engine bell housing and gearbox bell housing to see if all my holes lined up. Edited February 18, 2015 by jamie meachin Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 18, 2015 Author Share Posted February 18, 2015 (edited) The final parts of making this adaptor plate was to machine a piece of for the prop shaft as shown with the gearbox, shot blast the plate to make it look nice and machine the thickness of the adaptor plate off of the engine bell housing. A few pictures of the adaptor plate now mounted on the Cummins engine. Edited February 18, 2015 by jamie meachin Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 18, 2015 Author Share Posted February 18, 2015 Trevor, The fixture will come in handy again as I have another engine coming soon and a 1941 GMC at home...... Quote Link to comment Share on other sites More sharing options...
GeePig Posted February 18, 2015 Share Posted February 18, 2015 Ah, I thought you might! That is a very tidy piece of work, will there be pictures of it once you mount the engine in the vehicle? trevor Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 18, 2015 Author Share Posted February 18, 2015 Trevor, There will be pictures as my project unfolds yes. I have the gearbox and engine ready for painting at the moment. Looking forward to fitting it. Quote Link to comment Share on other sites More sharing options...
goanna Posted February 19, 2015 Share Posted February 19, 2015 (edited) Bridgeports are nice milling machines . Wish I had one . Thats a neat milling job , well done BTW I just gave away a 100kva generator powered by a cummins 6BT . The unit was given to me years ago but it just took up space . My neighbour owns it now . Mike PS what is that adapter made from , what steel ? Edited February 19, 2015 by goanna Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 19, 2015 Author Share Posted February 19, 2015 The plate was a 3/4" thick piece of mild steel. Couldn't tell you what grade though. Quote Link to comment Share on other sites More sharing options...
Toner Posted February 19, 2015 Share Posted February 19, 2015 I'm impressed. Good luck with the new engine. Quote Link to comment Share on other sites More sharing options...
fesm_ndt Posted February 19, 2015 Share Posted February 19, 2015 nice job Quote Link to comment Share on other sites More sharing options...
datadawg Posted February 19, 2015 Share Posted February 19, 2015 I'm impressed. Good luck with the new engine. Nice work. Amazing how necessity forces invention. Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted February 19, 2015 Share Posted February 19, 2015 (edited) That's an interesting approach and I hope the HT goes as well as the one we converted. Are you retaining the turbo? If so you might like to fit a liquid-to-air charge air cooler which replaces the inlet plate on top of the head. This will give you a little more power. I'm assuming you plan to re-use the existing radiator? If so you will almost certainly need to fit a header tank as these old rads are not designed to take the pressurised cooling system of a modern engine. If you don't fit a header tank it will probably spew the coolant out of the overflow until there's nothing left in the system but steam. Don't ask me how I know... And if you try just fitting a higher pressure cap you'll almost certainly burst the core. Alternatively if you plan to fit a modern rad you could fit a rad/intercooler pack and generate some real free power. FYI if anyone else reading this is inspired by the same idea, please contact me as I have a pile of the correct flywheel housings for this job. - MG Edited February 19, 2015 by TooTallMike Unintentionally came across as rude. Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 20, 2015 Author Share Posted February 20, 2015 Thanks Mike, that some useful information to take on bored. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted February 20, 2015 Share Posted February 20, 2015 Trevor, The fixture will come in handy again as I have another engine coming soon and a 1941 GMC at home...... You might want to do a little research if you are considering fitting one to a GMC as I think in the 50's or 60's the Dutch tried these to the original clark boxes and constantly blew them up. This is why I went down the route I took with the 6BT and ZF gearbox. Good luck. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted February 20, 2015 Share Posted February 20, 2015 I'm assuming you plan to re-use the existing radiator? If so you will almost certainly need to fit a header tank as these old rads are not designed to take the pressurised cooling system of a modern engine. If you don't fit a header tank it will probably spew the coolant out of the overflow until there's nothing left in the system but steam. Don't ask me how I know... And if you try just fitting a higher pressure cap you'll almost certainly burst the core. - MG This is an interesting thing as I know you have mentioned this to me in previous conversations, however I do not have a header tank on the GMC and the cap is not sealed tight. I do fill up the rad untill I can see the water over the baffel in the neck of the rad and then during the trip the level falls to a happy level, does not seem to matter how long the trip is. Then when I re top the water it only takes about a litre or so this seems consistant with how the old GMC engine use to opperate with the water level so no problems here at the moment. But the top of the rad is a fair bit higher than the top of the head on the Cummins. Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 20, 2015 Author Share Posted February 20, 2015 I'm going to try the same I have done for my Halftrack with our GMC, using the Cummims engine and the GMC gearbox. It should fit straight in as my granddad put a Perkins P6 in his years ago and the Cummins is shorter than the Perkins engine. Im going to look into the header tank, there is obviously a lot more room under the Halftrack bonnet compared to the GMC. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted February 20, 2015 Share Posted February 20, 2015 (edited) Jamie, I run a non-turbo 6B in a heavily laden Bedford MJR and would not hesitate to use the same in a GMC. They are a lively responsive little engine giving out 130hp even without a hair dryer, and unless you plan to tow a gigantic piece of WW2 arsenal around I see no necessity for a turbo. But the more pics of the R36BZF conversion I see the more I like it! I seem to recall comparing a 6b against a P6 and ruling it out for a GMC, but I might just have to measure up again if you are confident. I'm sometimes not too good with tape measures..... :-) I think the P6 required the rad to be moved forward? Which may be the only reason I ruled the 6B out? Perkins supplied a complete kit with all stuff required for the GMC conversion including a special flywheel housing to mate with the box and I believe brackets for the radiator move? Great work on the adapter rings! Tony Edited February 27, 2015 by N.O.S. Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 20, 2015 Author Share Posted February 20, 2015 Hello Tony, Yes Perkins did make a special bell housing and bits to fit the GMC. I think the radiator has to be moved forward but not enough to effect the bonnet, side panels ect. My granddad got 2 out of lime spreaders. We tow a Allis Chalmers crawler around on the back of our GMC hence wanting to do an engine conversion in that too. I find all these stories of engine conversions and what these engines are like, also it's interesting what approachs people have to engine converting. Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted February 20, 2015 Share Posted February 20, 2015 (edited) This is an interesting thing as I know you have mentioned this to me in previous conversations, however I do not have a header tank on the GMC and the cap is not sealed tight. I do fill up the rad untill I can see the water over the baffel in the neck of the rad and then during the trip the level falls to a happy level, does not seem to matter how long the trip is. Then when I re top the water it only takes about a litre or so this seems consistant with how the old GMC engine use to opperate with the water level so no problems here at the moment. But the top of the rad is a fair bit higher than the top of the head on the Cummins. Richard, Regular topping up is exactly my point. How often do you top your car up? Very rarely I'd imagine? Should be the same for a Cummins system, but only if you have a pressurised system with a header/expansion tank. Having a system with the potential to self-evacuate seems like a recipe for disaster to me... My old WLF was running the original rad and after a long journey there would be a stain of coolant running across the tops of both wings. At that time I hadn't done enough conversions to understand what the problem was. - MG Edited February 20, 2015 by TooTallMike Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 23, 2015 Author Share Posted February 23, 2015 After a busy weekend, I finally have the gearbox and engine painted and bolted together. I have a few little thing to sort out on the engine, mainly fixing the alternator and looking at putting a vacuum pump on there so I can still use the hydrovac brake system. Failing that I could use the vacuum from the manifold. Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted February 23, 2015 Share Posted February 23, 2015 Jamie, Manifold depression won't be enough. There is a vacuum pump available that bolts on in the compressor location. - MG After a busy weekend, I finally have the gearbox and engine painted and bolted together. I have a few little thing to sort out on the engine, mainly fixing the alternator and looking at putting a vacuum pump on there so I can still use the hydrovac brake system. Failing that I could use the vacuum from the manifold. Quote Link to comment Share on other sites More sharing options...
David Herbert Posted February 23, 2015 Share Posted February 23, 2015 Not only will manifold depression not be enough, there won't be any ! That engine has a turbo, its job is to presurise the manifold to get as much air as possible into the cylinders. The reasion petrol engines have vacuum in the manifold is because the speed is controlled by limiting how much air/fuel mix is sucked into the engine by a throttle valve in the carb. The engine is always trying to suck more so you get a vacuum. The speed of a diesel is controlled by limiting the amount of fuel injected, so the air can be as unrestricted as possible, or better still boosted by a turbo. Result no vacuum. Very nice piece of engineering though ! David Quote Link to comment Share on other sites More sharing options...
jamie meachin Posted February 23, 2015 Author Share Posted February 23, 2015 Mike, any idea on where I can find a vacuum pump for this engine? Quote Link to comment Share on other sites More sharing options...
R Cubed Posted February 23, 2015 Share Posted February 23, 2015 You can also get alternators with vacuum pumps on the back of them I think it has been metioned before that Ford transits do it this way, depending on what voltage you are using 12v or 24v this might be another option you could consider. Keep the pics coming. Why is the fuel filter where it is on top at the front of the engine ? usually down the side by the fuel pump. Quote Link to comment Share on other sites More sharing options...
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