Rebuilding the twin-cam: Part Two
So… As I might have mentioned in my last post, many components of my twin-cam 1600 were damaged beyond salvation by the time it landed in my garage. It took a bit of asking around, but eventually I came across all the replacement parts I needed. From the crank, all the way up to the cams, everything had to be replaced.
Once I had all the moving parts for the lower end of the engine (crankshaft, pistons, con-rods and fly wheel) I sent them all off to Durban to be balanced. This, however, took more than a month and a half.
Once I got the parts back, my first installation attempt showed up a huge problem with the new crank. It seized up solid once I tightened up the main bearing caps. This meant the engine had to go straight to the engineers, to find out where the issue was. It turned out, it was just a slight distortion of the bearing caps, and nothing too serious. The caps were bored out and now work very well.
There have been some issues fitting new parts to the engine, as this is such an early 105 engine, that many available parts don’t fit, as the market caters more for the more common, later models.
The new oil pump for my car was too tall for the early, short oil pan which was fitted to Sprint GTs. This meant I had to find a tall oil pan from a later car.
The gearbox in my car is from a later car. It’s still a mechanical-clutch box, and the only difference between the Sprint GT box and this one is the way the reverse gear is engaged. The early box has a “push down” reverse gear, and this one has a little spring plate which prevents you from shifting from 5th into reverse.
Another issue, is that the later bell-housing has three bolt-holes for the starter motor, whereas my early starter has only two bolt-holes. This also causes another problem; The crank-case breather, which is on the rear of the block, gets blocked by this slightly taller bell-housing, and the breather tube is displaced by that third starter bolt-hole.
I imagine this is why the breather was altogether missing from the engine when I got it. So, I had to have a new one made up from scratch. And I had bell-housing machined down to Sprint GT specs.
Now, all that’s missing is the cylinder head. It’s been with the engineers since November, and I hope to have it back soon. The rest of the engine parts are sitting about, all ready to go. But my wait for the cylinder head continues.