Misc: Everything Else Standard Comet Special

timetraveller

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I have said this before but I will repeat it. If you really want to get a handle on what a set of cams is doing then spend some time and produce a set of lift versus engine rotation, every ten degrees of engine rotation which is every five degrees of cam rotation. Once this is plotted out the one can see what is happening. The four degree BTDC equal lift system might be OK for well known cams but if you are playing about with cams with unknown qualities then it will pay to do the job properly. If you can use a spread sheet then you can produce the graphs you need with very little effort and you can also use the same spread sheet to show the velocity and acceleration curves. If you cannot do that then if you send me a list of lift versus engine degrees then I will set up the whole spread sheet for you and, if it is of interest to others, put the results on here.
 

Oldhaven

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Thanks TT, I'll do that, as it will answer most of my questions, but I am probably two weeks to a month away from getting the engine together enough to do it from the valves themselves. I may try it directly from the followers just to get a baseline.
 

Oldhaven

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I'm working on the Comet timing chest today and was hearing the big idler ring like a tuning fork as I spun the gears. On a whim I brought my phone with a chromatic tuner app over and it is ringing at E flat 7 with overtone at A8. I have the same idler on the Rapide and the tone is very familiar. Has anyone ever applied a damping coating to the center web of the idler?

Anyway, the spindles, oil pump, and bearings are all in now, and once I recheck the spindle shimming I should be able to button up the cases. I did change the cam bushings to oilite.
 

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greg brillus

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Check the grub screws at either end of the crank pin are tight, and pump some clean oil into the big end via the t/side mainshaft with an oil can. I had one that was missing one of these grub screws, resulted in a seized piston. This was on a 600 Comet with a TP crank assembly and top end kit. This was how I received the engine.
 

Cyborg

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Has anyone ever applied a damping coating to the center web of the idler?

No, but I thought about it. With an Alton added to the equation (with the rare earth magnets), the Comet's idler sounded like hells bells. Some kind soul assured me that the noise would disappear once it got above kicking speed.
 

davidd

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Ron,

Does the flywheel use the two taper roller drive bearings?

I used E flat tuning for years. It's easier on the fingers.

David
 

Oldhaven

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Hi David,

No, standard reduced width rollers. The timing side has been repaired and sleeved but the drive side is standard and OK.

P1050085 (Large).JPG

My wife, who is good in music theory, says that if the high note of the idler was an A flat or B flat it would be a more pleasant cacophany.
 

Cyborg

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I'm assuming it will get drowned out when the rest of the percussion section starts up. Sort of like the 3rd graders playing the 1812 overture.
 
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