Volkswagen: 69 Karmann Ghia, vw karmann ghia, compression check

Question
I recently bought a 1969 VW Karmann Ghia. It ran great for about 2 or 3 months. Then while driving one day, the engine lost power. I did a compression check and all cylinders have good compression. But both cylinders 3 and 4 do not seem to be firing. There is spark going to them but I am stumped now. Engine runs great but now only on 2 cylinders. What do you recommend I do next?

Answer
If you have compression, and there is spark present...

The most likely cause is that your valves are not opening or the intake manifold is leaking.

1) Disconnect the coil and turn the engine by hand with the valve cover off for number 3 & 4.  See if the lifters open and close the valves.

2) Reconnect the coil and start the engine, spray starting fluid where the intake manifold meets the head, see if there is a difference in the way it runs when you do this.

Let me know how you make out.

95% of the time it is one of these two things given your symptoms.  Great explanation of your problem.

Thanks,

Ron