6 - It Went BANG!
Starting over with the oil pump
I finally had some time with DiXiE, and started to get close to the exiting bit, but I was still unsure how the oil pumps would perform. What I needed was to make sure everything would work before the big fire up!
SO... I set up a jury-rig so that I could spin the engine over without the heads on. I clamped the bike down on my bike lift and put my electric Belle Mini Mixer (concrete mixer) in operation so that it turned the engine over like a rolling road would. Great. It all worked out fine, engine turned over real easy. I pre-oiled everything as I had a bleed off for the oil pump, and the idea was to dial-in oil feed untill I had enough flow and balance to all oiling points, which looked like it was going to happen at about 28 rpm.
I upped the rpm only to about 100 and things started to tighten up, the mixer started to protest and slow down, I'd stop everything, un-attach the mixer and spin over by hand, all seemed fine. I thought the mixer was playing up, I attached it again and thats when she went BANG!
The feed pump had hydraulic-locked as soon as things started to speed up. It had damaged the pump mount and timing cover, also, as you can see, the cam shaft .
I'm a bit disapointed to say the least! And I've been stumped as to what to do next ? I can still see a future in the use of AMC pumps, BUT I need a bit more R&D before attempting to use them again. I think the only thing I can do, as I am now desperate to get this bike running is try to look at Indian parts. Steve has lent me a '33 Chief oilpump body, which is nice of him, and it would be easy to repair the timing cover to take the pump, but I don't think any parts are available for these pumps, also the camshaft has to match the drive as well, are these pumps same as Sport Scout, are all pumps up to '38 the same? I'm not sure what to do, it has left me a bit stunned. BUGGER!!
Here's Moen's reply to my cam shaft and pump parts questions. Hmmm... (thinking cap on):
"As for early Indian pumps, the main problem is that the cam shafts to drive them are unavailable (pump plungers too, of course). The only shaft available is the 1938-up version. The earlier versions used different pitch/angles on the worm. See pic 1: one of the early plungers on the left - 741 (same as post 38 Chief) plunger + 1936-7 or so for comparison of thread angle."
"There were at least one, maybe 2, other versions of this drive. I think it went something like this: 1933 + part of 1934: single start thread on cam shaft. 1934 four start thread on cam shaft. 1934 (late) two start thread on cam shaft. And then I think they went to the final form, but I am not sure.
It might be possible to make a plunger for an early pump out of a 1938 plunger (lathe turning, maybe brazing), and then use a 1938 cam shaft to drive it. I *think* that you could upgrade the feed with a larger diameter feed plunger, but I am not sure - also not if this would overwhelm the scavenge plunger. These double ended pumps are generally considered marginal. See pic 2: 741 and 1936ish plungers. The early one is longer, with the thick end for scavenge and the thin one for feed - the 1938-style pumps still had the thin feed end, but the fat scavenge end cut off (new gear pump in the bottom of the pump body for scavenge). From 1941-47 they got the fat feed end in the pic."
After a bit of waiting for a 1938-up cam shaft and a 1941-47 oil pump plunger - and a lot of work and testing - I am happy to hold the Mk2 pump in my hand. 1933 pump modified to take the late plunger, driven by the late cam shaft. Personally I think it is the greatest achevement I have done to date.
The pump plunger/shuttle fits perfectly after boring out the 1933 pump body to accept the larger diameter of the shuttle. It runs and pumps wonderfully well .
Now we come to the non-Indian bits in the bottom of the pump for the return. The first thing is a piston that is spring loaded against the shuttle. There is a non-return valve that sits in the bottom of the pump in the oversized lower cap, this is on the outside of the pump return to tank, holding the head of oil in the return pipe. There is also a non-return valve in the sump, just like the Indian one but after the scraper and in the "oil sump flask" that I made (see part 5 of story).
The cracked cam cover was welded up, and a plan formed for adapting it to take the new oil pump. The fire/stove that I built in the spring is now pressed into operation for melting aluminium as a small furnace! It now has an oil feed and all the holes welded up to make a sump, this I fill with old used engine oil. Once a fire is burning, an old brake disc sits on top of the fire with a hole in it to hold a crucible, it works and melts aluminium quite well!
Now the casting. I had heard a lot of horror stories about the use of wet sand, plaster of paris, and all sorts of disasters, so I thought I'd go with what I know! I made up an "open cast" mold out of steel, with the timing cover clamped onto a steel base plate with supports out of steel to stop the cover sagging or distorting under the heat it was about to get exposed to. The cover was taken up to temperature on top of the furnace so there was no chance of any water getting in the mix.
I knew I needed to keep the temperature up, to at least try to get some "fusion" onto the case, so I poured about an inch of aluminium to great effect. Not only did I get a good platform for the oil pump, I got a fair amount of penetration and welded the cast to the case. The machining took all of one day as there was so much aluminium to take of, but its on the bike now.
I did have to mess around with the timing chest a bit, but also, as there is now a spare take-off on the rear cam shaft, I have taken out the train of gears that would have driven the magneto, and am now making up a drive platform for points on the spare cam/drive for my ignition.
There are lots of things that I have altered. The main oil feed to the crank is now a spring loaded bronze bush that slides in a sleeve then pushes against the pinion gear nut, and there seems to be enough oil getting through. I have had to change the oil sump flask so there is now a non-return valve. I have to lower the exhaust about 2" as the pump with its extra deep cap is too close, but I am not complaining. What I do like is that the pump looks like it's been on the bike forever.
The ignition case has two sets of points 201 and 159 degrees (that is 180 +/- half the cylinder angle of 42) apart but can be adjusted 3 or 4 degree each for fine adjustment. The points cam has only one lobe, the ignition case is able to rotate 60 degree easy so I have a lot to play with in the 40+ degree zone (if I need to). I have not made the means to do this from the handlebars yet.
The cover is screw-on. It all looks a bit big and out-there, but I have plans to cast a timing cover (some time on, when all is proven!) that will tidy things up a lot.
Earlier Installments of the DiXiE Story:
Part 1 - Presentation
Part 2 - End Float Mystery
Part 3 - DiXiE Oils Up!
Part 4 - Pumphouse Preview
Part 5 - Fit to Roll
More Chouts and Vintage Sprinting:
was no way of making a "snap-shut" Indian throttle, and the ACU say the
throttle must be of a snap-shut type. SO thats what I've made them; a quick
action brass left-hand snap-shut throttle. I like it, it looks older than
I am getting on with stuff and the next big job is the shagged-out old Linkert.
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