Divot worn in Valve Stem Options

[frank_c]

Hello,
I started replacing the Pushrod Tubes yesterday, and I noticed that the top of the stem of #4 intake valve has a divot worn in it from the rocker (#4 valve stem & rocker adj screw photos below). The other three valves on this bank are fine, and I haven't pulled the rockers on the other bank yet.

I purchased the car about a year ago, and here is some engine related info based on an engine build sheet, the receipts that came with the car, and what I can see:

• 2.0 with euro P&C
• Weber 40 IDFs
• WebCam #86
• Standard Aluminum pushrods
• Standard 2.0 rockers

I do not see valve springs listed on the build sheet, so I am assuming that the single spring currently installed is the OEM spring, and not an HD spring.

So, I have two goals here:

1. First is a short-term fix as I plan to take this car to the Hill Country Rallye in Mid-March - so no big tasks that might go off-script. Car will be driven 600-700 miles during this event.
2. Second is post-rallye where I plan to move to 1.7 rockers with swivel-feet, chromoly PRs, set valve geometry, and whatever else folks might suggest while I'm in there (solid rocker spacers?). And can this valve be saved? Am I looking at pulling the head to either repair or replace the valve?

For the short-term goal, if I leave things as-is this will obviously make setting the valve lash on that valve challenging. So I would like to hear folks' opinions on the use of a Valve Cap on that one valve (and any others with similar issue I may find). If I install a cap, should I replace the rocker adjustment screw for that valve as well? Or is there any other short-term option that does not involve pulling the head? Or just run it as-is knowing that #4 intake may not be getting full lift, and tear into it after the event?
Example valve caps: https://www.cbperformance.com/product-p/1522.htm

I also have some questions regarding the long-term fix, but I'll leave that for another thread when that time comes.





Thanks,
Frank

[Ninja]

I would not use steel pushrods in this application.

There are two levels of upgraded aluminum pushrods available. You need the cheaper version.

Most of the time the steel rods require a cold adjustment of zero lash.

In my book, this is a recipe for disaster.

The cams base circle has to be DEAD NUT perfect and if the valve or the seat wears AT ALL the valve is now held open on base circle.

Burned valves will be the final result.

I tested my stock 31K mile stock 914 camshafts base circle and came up with a variation over .002"!

If you have .006" valve clearance this variation effectively means nothing and is not service affecting.


As the engine heats up this clearance increases when steel pushrods are used so zero cold does not mean zero hot but it's still a BAD idea.

There is no margin for error with zero lash. (IMG:style_emoticons/default/ninja.gif)