I believe that the shutter speed is variable and is not clicked into the standard times.
What you could do is compare side by side the fstops in your E with the C. Lock them both open in Bulb and make some note or mark or landmark where the C is about the same as the E at the various stops. Then you could go to the trouble of side by side film tests with a hand operated 1 second exposure to see if your marks are perfect.