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| OKTomT:
I got the crank repaired. I really felt that the problem was the tapered crank pin hole because it took one more setup than the press fit hole. But after checking it I found that the offset of the press fit hole was off so I bored it over size and made a new crank pin out of 4130 pressed it back together and the main pins run at tir..002. I think if I do this again I will make the taper on the pins the same as a morse taper and use a reamer to clean up the holes. I have started on the crankcase. Here is a picture of what made so far. spec. 9" od tube x 2.375 end plate .250 |
| billmac:
Very glad to see that you got your crankshaft fixed. Just a suggestion for your fabricated crank case. With the taper roller bearings it is very important that the sides of your crank case are as stiff as possible. A flat plate may lack a bit in that area, but you can easily fix this by welding in some tapered webs radiating out from the main bearing area. This would also make your engine look much more like a typical cast crankcase. With your welding skills this should be fairly easy to do. |
| OKTomT:
Thanks Bill I will definitely add the webs to the drive side of the case. The cam side will get support from the cam box . I am working on the cylinder base and need to decide on the v angle. 45 degrees is what I am thinking of using and use a master rod and slave rod rather than a knife fork. Anyone have any thoughts on this ? |
| billmac:
45 degrees would be appropriate if you are making a Harley type engine. How about being a bit more radical and going for a high cam short pushrod design with about 50 degrees to get a Vincent look? It would be a bit more work but visually interesting. I guess the decision depends on what you want to do with the engine when finished. If you want to build a vintage frame around it then perhaps a vintage look engine would be better. A master slave rod design is typical of radial engines and should be doable in a twin. I think there would be some interesting design issues you would need to resolve though. Cam timing and design would need some thought. Master rod design from a stress viewpoint would be interesting - easy to get some significant bending stresses. Master/slave might be easier in a wide angle twin than, say 45 degrees. If you have sufficient room, a side by side big end might be easier than a knife and fork, but I'm not sure whether your crank case design will permit this. If it does, then it should aid cooling the rear cylinder a bit - cooling would definitely be a concern for a cast iron (or steel?) rear cylinder/head design. |
| OKTomT:
Hi guys I have made a little progress on the crankcase Here is some pictures of it. The v angle is 45 degree. |
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