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EVIC Update #8
Thursday, May 17, 2001 3:52 PM
With the addition of 19 new members who signed up at NAMES, the EVIC Interest Group now numbers 58. For those who missed or couldn't make the NAMES show, I was able to demonstrate my "Electronic Throttle", to show that the speed of the engine can be controlled by changing the valve timing alone. There are still some bugs to be worked out. The response is not as smooth as I would like and sometimes the engine fails to accelerate after it has been slowed down. On Sunday a broken solder connection to the ignition coil caused some problems from about 11:00 AM on. All told I was pleased with the suggestions I received and the interest shown in the EVIC engine.
Since NAMES I have run a few tests to see if I could improve the throttle response and solve the intermittent failure to accelerate problem. It turns out that the problems get worse as the engine heats up. I also observed an intermittent fuel draw problem that also gets worse with temperature. Yesterday I proved that the intake valve leaks when the cylinder head heats up. When it cools down the valve again seals perfectly. The head and the valve seat are aluminum and the valve is steel. My guess is that the problem is caused by the different expansion rates of the two metals.
I have seen many designs that use an aluminum head / valve seat and a steel valve. So I assume that this can be made to work. But perhaps some of these engines also have problems if or when they get hot. Perhaps those of you with lots of building and running experience can tell me if this has been a problem with other designs. Should I consider a steel valve seat insert? If so can they be press fit into place or will thermal expansion cause them to fall out? Your suggestions are most welcome.
After seeing my engine spitting out oil at NAMES Bob Heide decided that I need a proper set of piston rings. My EVIC has only one compression ring and won't keep oil in the crankcase. Bob made me a set of 3 rings, two compression and one oil ring. Thanks Bob. He made them using techniques similar to those that have appeared in Strictly IC and in Ron Colonna's Offy 270 book. Bob is building an Offy and has also started an EVIC. Ron was at the show and close enough that every time he started the Offy I was tempted to stop this experimenting and start building one. My, that engine sounds nice!
As soon as I get my shop back together (we moved 10 days before NAMES) I will make a new piston and, depending on the answers to my questions, modify the head. My goal is to then improve the Electronic Throttle and to demonstrate an improved EVIC at PRIME in September.
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