1" Bore x 1" Stroke Vertical I.C.

[Brian Rupnow]

Thanks Chris!!

[Brian Rupnow]

My greatest apologies to all who were following this thread. I was hoping to be finished by the end of February but my 74 year old body is causing me some distress right now, so I have to slow down a bit. Between carpal tunnel syndrome in my wrists and arthritis in my knees, I have been told by the doctor to back off a bit. There is the vague spectre of knee replacement surgery lurking in the background, but I doubt it will actually come to that. I will continue updating this thread (everything is completed except for the crankshaft and counterweights and spring keepers for the valves). Hang in there folks, this will get finished, just not as quickly as I had hoped.---Brian

[Admiral_dk]

Don't worry Brian - it's more important that you get well first.

Best wishes

Per

[Craig DeShong]

Hang in there Brian  and rest.  Don't worry; no one will finish your model for you while you're away 

Seriously, I feel for you and the knees.  I'm looking at possible knee replacement myself.  It's getting pretty tough to get around.  Interestingly, when I take my walk... getting down the hills is worse than going up ??? go figure.

[Brian Rupnow]

Craig--I find that as well. Whatever it is about coming a hill, it puts more stress on my legs than going up.

[Twizseven]

Hope you feel better soon Brian.  I was told 13 years ago that both knees were almost scrap and would want replacing within 10 years.  Not happened as yet.  Wife has just had both done in last 18 months and is moving around a lot better.  Again mine hurts going downhill.  Uphill and along the flat is okay.  Managed 6.5miles the other day and just a bit sore at the end.  The only problem going uphill is if I am carry something heavy like a pair of full 15 litre dive tanks.

Colin

[Brian Rupnow]

Okay!! I'm still fighting carpal tunnel in my hands, but today boredom got the better of me, so I've made a bit more progress. In a perfect world, I would machine all of my parts exactly to the drawings I make.---In the real world, I come close, but there are a few areas where this gets very critical.  One of these places is the width between the ball bearings in the crankcase. There is very little clearance between the inside of the ball bearings and the crankshaft, which is the part I'm making next. If there is too much clearance, then there will be issues of crankshaft endplay. The engine will still run okay, but there will be mysterious clanks and bangs issuing from the crankcase as the crankshaft revolves and slides back and forth between the bearings. If there isn't enough clearance, then the crankshaft won't revolve when the two halves of the crankcase are bolted tightly together. I don't have a tool that will reach down thru the top of the crankcase to measure the clearance between the bearings. My answer to this is to machine a couple of "sleeves" from 1/2" diameter material. One is slid over the end of a piece of 3/8" shafting and Loctited in place. After the Loctite has set up, the shaft is slid thru the bearing on one side of the crankcase and the sleeve is butted up against the inside of the ball bearing. The other sleeve is then slid over the other end of the 3/8" shaft, slid close to it's approximate position +1/2" and a dab of Loctite put on the shaft. Then quickly, before the Loctite sets up, the other half of the crankcase (with bearing in place) is slid over the shaft until it contacts the second sleeve and pushes it ahead of the bearing until the crankcases are touching each other and bolted together. After the Loctite has set up, the two crankcase halves will be separated and I can measure the distance outside to outside of the two sleeves which are loctited to the shaft. This will tell me what the exact distance is between the two ball bearings so I can machine the crankshaft to fit with about 0.010" of overall clearance.

[Bearcar1]

Elegantly brilliant. Crude, but effective. I like it!! 


BC1
Jim

[Art K]

Brian,
I like that idea, I may have to use it some day. I think it's to late for my stalled Upshur rebuild job.
Art

[Brian Rupnow]

This morning bright and early, and I'm looking for things I need to do yet. I'm about to make the valve spring retainers from brass, but I needed some reference dimensions from the valve springs I am going to use first, so I thought I might as well make a drawing of the springs while I had them out being measured.

[Brian Rupnow]

Here we have both valves, valve springs, and spring keepers assembled in the cylinder head. The valves were lapped into the seats first with #320 grit lapping paste, then 400 grit lapping paste, and finally with 600 grit lapping paste. After lapping the valves had the "handle portion" above the taper trimmed off and about .025" left at 5/16" diameter before the taper begins.

[Brian Rupnow]

This is something worth mentioning---I find that these small, slow running 4 cycle engines work well with a total valve opening of 0.080" to 0.100". This of course is determined by the shape of the cam.  It is always a good idea after the valve springs and valves are installed to use a finger to open the valve fully, and assure that the spring will actually let the valve open by about 0.025" more than that. If the spring compresses fully and the valve isn't opening as far as the cam dictates, something is going to bend or break. You will either bend the rocker, bend the pushrod, or (rarely) break the camshaft.

[Roger B]

Indeed  If you are running higher compression ratios it is also worth checking the clearance to the piston during the overlap period. A lump of Plasticine/modelling putty is a quick check. The engine jamming (but not Bob Marley) is also a good guideline.

[Brian Rupnow]

With my newly repaired mill, I was finally able to turn my round piece of 1144 stessproof steel into a bar. I swear to God, there is as much work getting the material from a round bar (which is the only shape you can buy) to a piece of flat bar as there is in all the rest of the crankshaft machining. I milled one side flat, then used the bandsaw to cut the other side flat, then used the mill again to machine the third side flat. I haven't machined any of it down to finished size, because I'm trying to machine it in a manner to keep ahead of any bending or twisting of the material as internal stresses are released. 1144 doesn't move much, but it does move.

[Brian Rupnow]

The crankshaft is up on the lathe being turned. In this view, I have just finished machining the con rod boss, and the con-rod is setting in place for a trial fit. All of the turning was done with the carbide nosed cut-off tool in the picture.