MY CORLISS
ENGINE BUILD
Part eight by Vince Cutajar
MY CORLISS
ENGINE BUILD
Part eight by Vince Cutajar
The plan to do the front cover first had to be put on hold as I realized that to make a nice fit of the front cover I had to first hone the cylinder bore down to size and I did not want to hone the bore before drilling the 20 port holes. So I drilled the port holes.
Took out the angle block and set it to 15 deg. and put the lot in the milling vice.
First thing I did was to make a flat surface with a 2mm slot drill.
First set of holes drilled with a 1.6mm drill. Second hole from the left is where I broke the tip of the 1mm centre drill. That will be OK as I still have to mill the pocket. Some more photos of the finished port holes.
Bringing the cylinder bore to size was mostly done by honing.
For the front cover I used a 45mm round section BMS and machined it to a diameter of 42mm and then machined the boss that goes into the cylinder to a slip fit.
It was then parted off. Changed my attention to the cylinder so that I could drill and tap 3mm the bolt holes for the front cover. Decided to use the DRO bolt hole function. Problem was that I had never used it so it took some time to figure out how to use it. To make sure I spotted the position of the holes with a marker just to make sure that they came out where I wanted them. I then drilled and tapped each hole one after the other. I hate tapping shallow blind holes. I had an ‘oops’ when using the first taper tap I stripped the thread but managed to save it with the second and final tap. I also ground off the point of each tap to go a little deeper with each tap.
I then wedged the front cover boss into the cylinder by using a piece of paper between the boss and the cylinder bore to make sure it did not move. Using the same bolt hole function I spotted the eight holes on the front cover.
The 3mm holes in the front cover were then drilled and a trial fit was attempted. Would you believe it, they actually fitted. WOW!
The hole where I had a problem with the first tap is a little skewed but still works. That was a relief.
I continued machining the front cover and left a 2mm boss on the outside.
I then continued machining the front cover and left a 2mm boss on the outside.
I assumed that the front cover needed a gasket. So I made a couple of gaskets from the thinnest gasket material I could find.
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