Tappet clearance - a thermal analysis

hybridracer

hybridracer

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I've created a mathematical model of the Norton Heavy Weight twin engine in order to investigate the tappet clearance variation with temperature. It will take a while for me to thoroughly test it before publishing results but I just wish I had done it decades ago.
I have fairly good values for the coefficients of thermal expansion of the different materials but I could do with some help in choosing accurate mean temperatures for the various components, in particular for the valves, which have the largest effect on clearance. If anyone has actually measured operating temperatures anywhere in the engine that would be great.
 
I rode my stock 1972 Combat and did temp checks , All temps in Fahrenheit
head = 280-300 degrees
Cylinder base=280
oil temp in tank 160 at bottom 140 at top.
Very little if any change in Exhaust tappet adjust of .010 = 10 Thou cold or hot
at that time base of the spring was about 260.

The engine makes good power and makes good heat.
 
Carl H said:
I rode my stock 1972 Combat and did temp checks , All temps in Fahrenheit
head = 280-300 degrees
Cylinder base=280
oil temp in tank 160 at bottom 140 at top.
Very little if any change in Exhaust tappet adjust of .010 = 10 Thou cold or hot
at that time base of the spring was about 260.

The engine makes good power and makes good heat.
Click to expand...
Thanks for your info, I didn't think the head and barrels would get that hot!
It is good that the exhaust clearance doesn't change because the polydyne quietening ramps on the Combat cam ( and the 3s and 4s cams) make it vital that the correct clearance is maintained.

My initial model was probably too simple so I am adding the clamping effect of all the bolts /studs to find out what is important to include.
 
Carl H said:
I rode my stock 1972 Combat and did temp checks , All temps in Fahrenheit
head = 280-300 degrees
Cylinder base=280
oil temp in tank 160 at bottom 140 at top.
Very little if any change in Exhaust tappet adjust of .010 = 10 Thou cold or hot
at that time base of the spring was about 260.

The engine makes good power and makes good heat.
Click to expand...
Why is the oil hotter at the bottom of the tank ??
 
I recall several years ago Comnoz posting data from his well-instrumented personal ride where EX valve pocket temperatures in the 390F (199C) range were recorded.
 
I just ride if the Norton is running great even better which is every time I take it out, air cool motors do run hotter and summer time even more so, I have always ran an oil cooler on all my air cool British bikes and installed the Lochead cooler within 12 months of buying my Norton new, made a big difference and better oil than what the dealer was using, I have got long life out of all my AC motors and very good reliability, and I don't use a thermostat, the motor has no troubles getting up to temp without one.
It's been so long since I had the rocker covers off, but I do know when the tappets need checking just by the sound of my motor.
When my motor is running great I don't touch it except for oil changes when needed, I run Pennrite 50/70 grade for older bikes with a mixture of STP, I have been using STP mixture for over 38 years and think why I get long life out of my Norton motor.

Ashley
 
Lineslinger said:
Ash, that's the wrong oil to use.
Click to expand...
Ash might mean this stuff.
Tappet clearance - a thermal analysis
 
Lineslinger said:
Ash, that's the wrong oil to use.
Click to expand...
Farkkkkk my motor is domed, no its not the wrong oil its design for older classic bikes and I been running it for years without any problems at all, just did an oil change and not one bit of metal on the drain plug magnet, I use to run a straight 50 racing Pennzoil for over 30 years brought from a old yank who imported it by the barrels, but it got harder to get, the Pennzoil we get here now is made by Caltex and isn't the same, why I switch to Penrite 50/70 grade for classic bikes + the added STP.
I have owned my Norton for over 47 years now since new so I think I know what my bike likes, has well over 160k miles and is only on its first oversize rebore and in my youth it copped a canning, so I will stick to what I know best for my motor, it has never let me down in over 47 years and it was a everyday rider till 2013 and now it's semi-retired just like it's owner.

Ashley
 
I still look to Jim's tests as though it is possible they are meaningless they are also the only tests that were the same for every oil and we know the tester wasn't leaving his thumb on the scale.
Me? The 850 gets Castrol 20-50 Classic because I change oil every 1k and the price is about average.
 
robs ss said:
How do you get a "Double Layer" with oil?
As soon as I read that sort of tripe I assume the rest of the ad is tripe too.
Not saying it is a bad oil - just that ad-men should be put in stocks and pelted with whatever suits us.
Click to expand...
I didn't write it , but I think the double layer of protection , might mean the added zinc and it does have the base oil for engine wear protection 🤣🤣🤣 .
 
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