Need some help, Troubleshooting my car Options

[914curt]

I am having trouble with my 914. I have a 1974 1.8L that is bored to a 2.0L with dual 40mm carbs on it, that is about all i know about the motor. I purchased the car with this engine in it and was told it had a 1.8 turned in to a 2.0. The problem i am having is that it has completlely run out of power it was running good last summer but at the end before i put it away for the winter it got really bad. it will not accelerate at all. But sometimes it does. it is intermitent. Today i tool it out and it ran fine at first and them went to crap. it had no power and was back firing like crazy. I have put a new ignition system in the car, and changed the plugs today. when i checked the plugs all of them looked good except cylinder three. It was completly black, like covered in oil. the rest of them looked great like they were supposed to be. after changing the plugs there was no difference in the performance in the car. i was thinking that the problem could be the rings in cylinder 3 but i am a very novice mechanic. this is my first time trouble shooting a car by myself. Could anybody give me some advice or ideas on what it could be or if i am right about the rings.

Curt

[need4speed]

All of those are great ideas, but for a novice mechanic, I'd check in this order (simplest/most likely -> difficult/hopefully less likely);

1) That #3 is suspicious, check that plug wire to make sure it's getting spark. My bet is that this is the problem. But even if you fix it, you probably should check #2 and #3 also.

2) Timing/Dwell. Low power and backfiring is very commonly caused by insufficient advance, and it's simple to check with a screwdriver and a timing light.

3) Valve lash. Sechzylinder is right, and if your valves aren't adjusted properly, you could quickly develop a very unhappy motor. Adjusting the valves is really a simple job, perhaps a bit time consuming, and for a novice mechanic, a bit daunting. It should be done every 3000 miles, and if you find them way out of spec, and get them adjusted properly, you'll find it's like getting a brand new engine.

4) Overhaul those carbs. Take em off, clean em out, adjust em, balance em, put em back on. Make sure there's no crud or rust or sediment or lime scale, etc. Change the fuel filter, even check the fuel lines, inside the empty tank for rust, etc. Crud in the fuel system will make you endlessly mess around tweaking this and that trying to get an engine running right. Worse, the symptoms of this can be intermittent, making you THINK you've fixed it, then a week later it comes back. With carbs, on the fuel system, work like a surgeon.

5) Compression. If all of the above doesn't fix it, then you could have bad rings. But I'd say if you had rings THAT bad, run the engine, take off the oil-fill cap, and look for blue smoke. If you have blue smoke coming out of your oil filler, then bad rings are pretty likely, and you need to test the compression with a compression gauge. Bad rings are bad news. Expensive news. (IMG:style_emoticons/default/hanged.gif)