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| shred:
Thought I'd posted my video of the PD engine running with the valve spool and all.. but it turned out the only posted video shows it running with the valve on, but not operation of the valve ltself.. sorry Bogs :scratch: Anyway, kvom, those parts are looking good and the notes are very useful as well. Keep it up. |
| kvom:
After a 4-day weekend offroading the Jeep and 3 more days doing various maintenance work, I finally had an afternoon in the shop to get back to the engine. First I finished all of the remaining drilling on the 4 headers (I will need to remake the 5th). Then I put one of them together completely along with the cylinder. Here's a looksee: Originally I was going to leave the valve cover thicker than the plans, as I had made them from .25" thick brass plate. However, I needed to attach them with the shortest screws, so the options were to machine them thinner or cut the counterbores deeper. FWIW, I milled the counterbores with a 3/16" endmill; the plans show using a 1/8" endmill, but since the head of the screw is larger than that milling the bores is more complicated/tedious. Some of the brass plungers were a bit too large to fit the holes, even though I measured them at .125" and the holes were reamed with a .126" reamer. Once they're machined they are a PITA to hold and polish down to size (I used a needlenose plier). So a recommended alternative would be to make the heads first and test for fit on the lathe before parting off and machining the heads. Next step is to clean up the interiors of the cam housing and crankcase, plus part off the crankcase and make some pistons. Then it will be time for a trial assembly. I also need to start thinking of a mount design. |
| kvom:
I had another full afternoon in the shop. Today I started with the pistons. Chucking some 1/2" diameter aluminum rod, for each I turned 1/2" length down to .375 and individually fitted each to its own piston, trying to attain a rough sliding fit. Then I parted each off, To finish a piston, I chucked it in a 5C collet block with .25" exposed, then placed the block vertically in the mill vise. I used an edge finder the first time to find the center. First operation was to mill off the nub from parting and bring to length. Then with a 1/8" endmill (1/16" for the master piston) I cut a slot .200" deep, then widened the slot .003" on each side with two more passes. Then it was a simple matter to chuck the collet block horizontally and spot drill/drill the cross hole for the wrist pin. Once removed from the collet and deburred, I was able to assemble the conrods to the pistons using the pins supplied by Liney. The holes are not a press fit, but I doubt that's critical. Here's a "family" portrait: The pistons still need a bit of toothpaste lapping to slide smoothly. I didn't cut any oil grooves but I did chamfer the tops of the pistons. After smoothing the inside of the cam housing with Scotchbrite, I wanted to do a trial assembly of the front portion of the engine. The first task was to machine the bearing carrier to its planned thickness of .125". I had previously parted it off oversize and needed to removed .016" from the back. To do this I decided to use my "new" chuck with soft jaws on the lathe. I had made the jaws over a month previously, but this was the first opportunity to try it. First, I machined a pocket .100" deep and 1.275" in diameter to match the part. This allowed me to then chuck the disc securely and take the facing cut: Now after deburring, I laid out the components for assembly: Cam housing, front bearing, driveshaft, rear bearing, and bearing carrier: The rear bearing is a tight fit to the bearing carrier: Then screw the bearing carrier to the cam housing to complete the assembly: It's important that the bearing carrier press both bearing firmly against the driveshaft to eliminate any slack but not so that the "preload" causes binding. I need to do some tweaking here. I also noticed a few more issues to fiddle with. 1) The plunger holes are slightly too small for the supplied ball bearings to slide freely, so may need deburring or mild filing. 2) The rear cam seems a bit too far forward and may be interfering with the front plungers. I may need to add a shim. 3) The crank is not sitting perfectly straight on the end of the shaft. I suspect the counterbore bottom is not flat. In any case, the thickness of the crank or depth of the counterbore can be modified to center the conrods under the cylinders, so I will hold off until I'm ready to fit the crankcase. |
| chuck foster:
looking good kvom :thumbup: :thumbup: there is allot of parts to this engine and they seam to be kinda small :bugeye: but you are making it look easy. cant wait to see this one run :ddb: :ddb: :ddb: chuck :wave: |
| Darren:
Looking good there Kirk, that looks like a fiddly engine with all those tiny bits, :thumbup: |
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