jamie meachin

Hello Richard, I will have a look this weekend for you and let you know. I have a feeling the guy I know at the bus company said they are around the 160 HP mark. Jamie

Finally got the engine blocked up and say in the chassis this weekend. I'm surprised how small this engine is compared to the original. Next step is to modify the engine mounts.

Richard, I'm using 24 volt start and 12 volt electrics. The fuel filter on the front at the top of the engine is something the bus company dose. I'm guessing lack of space in the engine bay? I will be moving it once I get it in the chassis. I can get you some pictures of the Perkins P6 engine in a GMC. Jamie

Mike, any idea on where I can find a vacuum pump for this engine?

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.

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.

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.

Thanks Mike, that some useful information to take on bored.

The plate was a 3/4" thick piece of mild steel. Couldn't tell you what grade though.

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.

Trevor, The fixture will come in handy again as I have another engine coming soon and a 1941 GMC at home......

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.

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.

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.

Hello Mike, Yes I have an original gearbox, the bell-housing of the engine and gearbox is about an 1 1/2" difference. I have made my adaptor plate now and all bolts together perfect. I will start a thread soon about the plate and conversion.