noisy ex valve( screeching)

[michael snellin]

Hi, i have removed the head on the above and found that the valve fits perfect in the guide, no probs,put the head back,still there is the noise, its when the valve is about to close its noisy against the rocker (seems to jump from open to close) getting a bit of a dab hand now putting the push rods in (urgh !!!!) any thoughts on the noise ????.

[RichardL]

Just another guess: maybe, oil starvation to one end of the rocker shaft?

[bsa-bill]

 a long shot but one I looked at when I had the same valve hesitation, I had thought the crankweb might be catching on one of the long studs for the primary case (front three) and this combined with new valve and guide might produce a momentary hiatus  accounting for the valve pausing for a nanosecond hence the click, as it happened one of the studs was catching the web and needed a bit ground off but I discounted this as the cause and went for the ZX1 cure.

Never thought about it again until now but it does seem a bit of a stretch, however it would take but a minute to slacken the studs a couple of turns and see what happens

[muskrat]

Are you sure it's not backlash in the timing gears? Take both timing covers off, wind over till bottom of stroke and take the idler pinion out. Now turn the cam via it's nut clockwise a few turns. You will be able to turn the cam very slowly and observe the valve actions.
Caution : When replacing the idler pinion put it in but don't mesh the teeth and turn the cam till the marks line up. Then turn the crank to line it's dots up, then push the idler in to mesh with both. Winding the crank with the cam in any old position could/would bend a valve.
Cheers

[michael snellin]

Hi, thanks for all the info, I will give it a go, as now i am at the end of suggestions when you put your hand on the top of the valve /rocker you can feel it jumping dont know what to do now?? might put a new valve and springs in just to see what happens. i have also kept the rocker box far as it will go to clear the valve collar etc, etc,

adm edit: topics merged

[jjbsa]

I have seen a screeching problem just like you descibe on an A65. It was caused by having too large a washer underneath the cylinder head bolt that sits between the cylinders.  The outside of the washer was scraping on the exhaust pushrods.  The pre-unit engines are tight on space in that area too, so it might be worth a look

[jjbsa]

Hi Michael, did you get it sorted out?  The A65 I mentioned above had a groove cut into its pushrods where they had been scraping the washer.  The noise when the engine was running was dire - very loud.  HTH.