mauro6569

for a while my 964 ran with 5 cylinders because the 2 spark plugs of cylinder 3 were burnt. in these days I have lowered the engine for work and I have disassembled the exhausts. I noticed that the exhaust valve of cylinder 3 is dirty with oil. (see photo) can it be caused by the reason described above?

r-mm

Sounds to me the oil ingress is the cause of the sparkplug fouling. Valve guides would seem a likely culprit.

mauro6569

thank you. but the other exhaust valves are all dry. only this of cylinder 3 is encrusted. Engine ran with non-functioning cylinder 3 spark plugs for a period. then the exhaust valve has discharged gasoline and unburned gases. I believe it may be the cause of this problem

darylbowden

His point is that something caused those two spark plugs to get burnt. That the rest of the cylinders didn't experience that would point to this being something unique to cylinder 3. It is not common to just have two burnt spark plugs in any cylinder and so what you need to look for is the cause of that. I'm not enough of an expert in these engines to give you a qualified answer to that, but it would appear oil ingress is a likely culprit, however it occurred.

mauro6569

Thanks for your suggestions. I also have another problem: I bought the bushings and bearings for the clutch pressure plate bearing fork from rosepassion but they look slightly large. must they enter the gallows freely or must they be forced in to make them tighten?

r-mm

Oh boy there are many versions of that bushing. Which one did you buy.

budge96

If I understand you correctly the bearings for the clutch fork are small needle bearings that sit in a sleeve and are inserted into the holes on each side it is quite fiddly and if I recall it easiest to mount the far bearing in the hole and position the rod to catch both ..,takes a few tries before you get the hang of it .
I taped the fork to the clutch of I remember , then installed the clutch fork rod once engine was mated...YMMV , Bert