Valve closure

[mizike77]

While I was cleaning my heads from my 79 Darmah ,I noticed that the valves dont seam to close fully. I can rotate the cam by hand and with the valves closed If I spray carb cleaner into the intake or exuast ports it seeps out from around the valves. This happens on both heads , all four valves.Do I need a valve job? Do the valves just need to be adjusted? Or will they close up tighter when the engine is running due to compression?

[Lumpy]

I`ve made up a tool where I mount a dial indicator over the valve, it also has a small screw that bears on the edge of the closing rocker to gentley push the closer agains the cam lobe, this I ONLY screw down by fingers, and then not too tight. Bring the cylinder to TDC and then push the valve down against the hair spring/closing rocker/cam lobe. Make sure you have clearance at the opener before you start. If I get more than .003" I re-shim and aim to have .001". I then check that I can rotate the shim by fingers at different sections around the cam lobe. I`ve found this way to be far more acurate and a lot quicker and easier to do than to mess about with feeler gauges. You then need to purchase the little measuring slug for the closer shim, measure with a micrometer and order new. Remember it`s always better to er on the loose side as going too tight has disasterous results. You can get a pretty good idea as to how they are adjustment and seal wise from the way she starts up and the idle tic over.
However if your not that mechanically inclined or don`t posses the tools I would take it to a professional. As I say, horror stories abound of broken Duc`s that had dodgey valve jobs performed on them.

[wdietz186]

Mike, First make sure the valves have clearance on the openers when at TDC. If the adjustment is too tight the valve won't fully seat. The next thing to check is if the valve seat and face are free of carbon as small particles can interfere with seating and allow the seepage you describe. Since you have the heads off you can take the valves out and clean things up. Lapping the valves will restore the sealing surfaces of the valves and seats. You will probably have to reshim the valves after but you have it all apart anyway. It is also a good time to inspect the guides. If they need to be replaced the valve seats will need to be recut and the valves refaced or replaced. These kind of discoveries tend to snowball the deeper you look into them. But doing things right keeps you from doing things over.

[Grover]

+1 for wdietz186 advice, may I add that I would replace the retaining colletts (8) that hold the valves into the shim........they do fracture in survice and it's REAL cheap insurance!!!!