Do I really need a new valve???

BenI · 05-26-2000, 12:02 PM

I have a '74 914 with a 2.0L case that has been bored out to be 2.4L. I recently found, while adjusting the valves, that my adjuster screws had worn seriously since i last checked. The worst news came in the form of two little metal half-circles that were in the valve cover on the pass. side. They turned out to be the innermost track of both halves of a valve cone (the retainer that fits into the groves on the vlave stem to hold the valve spring disk). I dont know which valve they came from, but suspect the #4 cyl exhaust valve since its adjuster screw was the most badly worn.
I have two questions:
1) Has anyone heard of valve cones breaking before?
2) Knowing that the valve cone is damaged, should I remove the head and replace the valve for fear that it may be damaged?

I will be able to replace the cones without pulling the head, and am positive that the valve stem tips have not mushroomed.

Thank you for any input and opinions.

Ben

John Rogers · 05-26-2000, 01:48 PM

There is an adapter that goes on the spark plug hole to allow you to pressurize the cylinder and then a spring compressor to be used to remove the retainer and replace the cones and inspect the spring(s), etc. It would be easiest to lower the engine to give you room to work. If only the adjuster is worn/damaged then you might not have to replace the valve. Inspect the top of the valve stem carefully with a light and magnifier glass so see if there is damage. Some things to check are: make sure the adjusters are lined up with the valve stem. While the springs are removed you can check side play between the valve stem and valve guide and if it is over spec than damage probably has occured. My daughter's 914 recently had a rocker move to the side due to broken rocker shaft shims and it made a terrific racket but did no damage. Use Pinto adjusters or some with swivel feet to spread out the load and finally if you auto-x, adjust the valves after each days running. Good luck.

[This message has been edited by john rogers (edited 05-26-2000).]