Perkins 1/4 scale hit and miss

[Gordon]

I have been building three 1/4 scale Perkins hit and miss engines. Apparently I am missing something and I cannot nail it down. The cam is only giving me about 1/32" of travel. This makes a very short exhaust stroke and a very touchy governor. That only gives an open exhaust valve from 0° BDC to about 30° beyond BDC.

If anyone has built this engine I would like to get in touch with them with this and some other questions.

Thanks: Gordon

 

[Gordon]

Immediate problem solved. I finally redrew the parts in CAD and found a math error. I should have redrawn everything in the first place as I usually do. I catch many errors and misinterpretations that way. Usually the problem with the original drawings, as it was in this case, is that parts are dimentioned from different points so math is required to determine location. When work is located in the mill everything is located from the indexed location, not the other side or some center line.

 

[Ken Brunskill]

I am interested in modeling this engine as well, can you provide a source of the drawings/plans. Like you, I redraw everything I build using Solidworks. This partly for learning & becoming more proficient with it, thinking through the machining setups, and having a 3D model that I can observe the motions.