Valve Adjustment, ...why did I have zero clearance? Options

[tomeric914]

I had adjusted the valves to .006" before the last track event I went to in April. It was about a 4 hour drive to the track and probably 40 or 50 degrees F. When I got there, the darn thing wouldn't idle (dual IDF 40's, 2.1L). No matter what adjustments I made, I couldn't get it to idle when hot (right off the track) but it would idle if it sat for a while. So I came home from the event, parked the car and started on the flare installation.

Now 3 months later with flares on and driving it on a regular basis, it still didn't idle. Again, checked the synchronization on the carbs, idle mixture, etc. Still didn't idle. Thinking logically, if it won't idle hot, a valve must be sticking open. So I let the car sit for a day and pulled the valve covers to find that all 4 exhaust valves had ZERO (more like negative) clearance! (IMG:style_emoticons/default/WTF.gif)

So what happened?

A. The valves all stretched the same length.

B. All the seats got mashed evenly

C. The valves weren't adjusted at TDC

D. It was about 20 deg F in the garage when I adjusted them last


A and/or B? I doubt it.

D seems the most logical but does the valve grow .006" over 60 degrees?

You would think that finding TDC doesn't matter, but I believe it does. Years ago I tried adjusting them with what is now referred to as the "rocking method" using the opposite side valve as a guide with the theory that a valve closed is a valve closed anywhere on the cam. I found when checking the clearance at TDC that the valve did not have the same clearance as measured when using the rocking method. It ended up being too tight at TDC!

On my 914, the flywheel is paint marked at the groove for TDC and 28 deg BTDC. If I used the 28 deg BTDC mark, I was on another part of the cam that resulted in a different clearance than at TDC. The result being a valve held open when the engine is hot and no idle.

After adjusting the valves at TDC and confirming all adjustment through one rotation, it idles perfectly.

[jaxdream]

Ok , TDC it is , but is it TDC for every cylinder ?? As that would make sence. TDC for #1 , then rotate engine , watch distributor rotor when it comes upon the next plug wire point for firing ?? This can get confusing with all the tried and true methods. (IMG:style_emoticons/default/dry.gif)

Jack / Jaxdream