TOPIC:

Try adjusting your idle air screw for number 4 should be set at roughly 3 to 3.5 turns. Your compression is good, information you have given only relates to number 4 cylinder not firing, so would suspect carb as opposed to coils. Or you may have a faulty Spark Plug or HT lead cap etc

just started reading this post now.
so my question is did you do any head work ie valve job and if so if one of the valves was put in dry if may have stuck and been hit by the piston* (slightly bent now) causing the ticking sound. went back and listened to the video sounds like a shim clearance problem does the sound change if you disconnect the plug wire to #4 as its running or any other cyl (one at time)

*although that should be reflected in a compression test.

I would check the shims for surface flat. You need a micrometer and measure in the centre of the shim and the rim. If there is more than 0.0005 in then chuck it. Also check the surface condition for hard facing starting to deteriorate which can cause big damage to the cam lobe if left too long.

To explain why the shim would tick the shim would be flexing and could click just like the old tin toys that clicked when you pushed the tab specially made to drive your parents to insanity.
Check the bucket to make sure the shim sits flat and doesnt rock even the slightest bit would cause a click.

What Mark was saying about plug caps could be a good place to check a lose spark can sound like a click.

Mark wrote: Try adjusting your idle air screw for number 4 should be set at roughly 3 to 3.5 turns. Your compression is good, information you have given only relates to number 4 cylinder not firing, so would suspect carb as opposed to coils. Or you may have a faulty Spark Plug or HT lead cap etc

Ahh yes the pesky no. 4 idle air screw, can only be done accurately with the carbs off in my experience.

stocktoy wrote: just started reading this post now.
so my question is did you do any head work ie valve job and if so if one of the valves was put in dry if may have stuck and been hit by the piston* (slightly bent now) causing the ticking sound. went back and listened to the video sounds like a shim clearance problem does the sound change if you disconnect the plug wire to #4 as its running or any other cyl (one at time)

*although that should be reflected in a compression test.

No head work has been done (yet ). Yep I did disconnect all of the spark plug wires (one at a time), as it was running but the stubborn tick remained in each case.

RickG wrote: I would check the shims for surface flat. You need a micrometer and measure in the centre of the shim and the rim. If there is more than 0.0005 in then chuck it. Also check the surface condition for hard facing starting to deteriorate which can cause big damage to the cam lobe if left too long.

To explain why the shim would tick the shim would be flexing and could click just like the old tin toys that clicked when you pushed the tab specially made to drive your parents to insanity.
Check the bucket to make sure the shim sits flat and doesnt rock even the slightest bit would cause a click.

What Mark was saying about plug caps could be a good place to check a lose spark can sound like a click.

I got a bit dejected and stopped thinking what the next step would be, so thanks goes out you Rick for getting me on track again. Actually the loose spark is what I think it sounds like but couldn't think how to describe it at the time. I have also had the ColorTune onto it 2 days ago and all 6 were fine.

I will check all those things tomorrow starting with the plug caps and the HT leads. Then finish off with a dessert of shimming. It will have had plenty of time to cool down by then (23 deg C here today)