21-10-2022, 11:56 AM
Hi Denis
I have read your pdf with interest, I guess you are frustrated that there hasn't been an "Ah Ha" moment and nothing is obviously wrong. As I previously mentioned, my engine is also a 2 bearing with a HC head. It sounds a bit generally harsh but this smooths out when its properly warmed up and is only really apparent around 1900 to 2400 RPM when the throttle is more than about 2/3rds open. I too have 4 thou end float on the camshaft. I attribute the harshness ( I wouldn't describe it as knocking) to general wear in the path from crank to distributor (3 gear pairs), causing timing scatter.
The oil and carbon looks like my engine did the last time it was apart. In my case I suspect this was partly oil coming past the rings because the bores were glazed, maybe due to incorrect running in technique on my part. The other factor is the choice of plugs, in road use these engines seem more inclined to run cool rather than hot. If the plug tips don't get got enough then they can cause a slight misfire and exacerbate the carbon deposit problem. I found a change to a "hotter/softer" plug helped, I run (genuine) NGK B6HS but some people go to a B5HS type which is one step hotter.
Re-reading this long thread, did you ever definitely establish whether your noise was load/throttle related or only RPM related ? It makes a big difference to the potential causes. Even the propshaft turns at engine RPM in top gear.
I have read your pdf with interest, I guess you are frustrated that there hasn't been an "Ah Ha" moment and nothing is obviously wrong. As I previously mentioned, my engine is also a 2 bearing with a HC head. It sounds a bit generally harsh but this smooths out when its properly warmed up and is only really apparent around 1900 to 2400 RPM when the throttle is more than about 2/3rds open. I too have 4 thou end float on the camshaft. I attribute the harshness ( I wouldn't describe it as knocking) to general wear in the path from crank to distributor (3 gear pairs), causing timing scatter.
The oil and carbon looks like my engine did the last time it was apart. In my case I suspect this was partly oil coming past the rings because the bores were glazed, maybe due to incorrect running in technique on my part. The other factor is the choice of plugs, in road use these engines seem more inclined to run cool rather than hot. If the plug tips don't get got enough then they can cause a slight misfire and exacerbate the carbon deposit problem. I found a change to a "hotter/softer" plug helped, I run (genuine) NGK B6HS but some people go to a B5HS type which is one step hotter.
Re-reading this long thread, did you ever definitely establish whether your noise was load/throttle related or only RPM related ? It makes a big difference to the potential causes. Even the propshaft turns at engine RPM in top gear.