rhah
Admit it, your cruisers jealous
Day one run on poughkeepsie gulch stuck waiting to get my tow the rest of the way up. Thanks jason
Solid Axle Summit 2017 - Ouray, CO
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These pictures are sooooo great!!
A note on altitude...
The engine cooling system is a sealed system and the pressure it reaches (12-15 psi depending on the cap) is independent of the atmospheric pressure or altitude. The cooling system maximum pressure is governed by the spring pressure of the radiator cap and nothing else.
At sea level or at 13,000 feet, the pressure inside a hot engine cooling system is exactly the same. That being so, the coolant boiling temperature inside the engine is exactly the same at sea level as it is at 13,000 feet (or in outer space for that matter).
The overheating that some engines experienced (probably the 2F carbys?) at extreme altitude may not have been caused by cooling system malfunction unless the radiator or cap was faulty, it was likely because of wrong air/fuel mixtures (too rich) and ignition timing that was too retarded for the oxygen depleted atmosphere at that extreme elevation.
Oxygen thin air found at extreme elevations makes the gas mixture burn slower, so the timing needs to be advanced farther than usual at extreme altitude.
Driving up long, very high, mountain grades with the pedal to the floor (often necessary with a 2F) with retarded ignition timing and out of whack fuel mixture is going to overwhelm any cooling system after a while. Too much of the heat of combustion gets absorbed into the cylinder walls instead of being converted to efficient piston downwards force. If the timing is too retarded, (because of extreme altitude) the late burning flame in the cylinder can actually be blown out the exhaust ports... which overheat the exhaust valves.... and can warp them. Aka burnt valve.
The HAC system in the 2F FJ60 isn't tuned for the extremes in altitude (13,000 feet) that are found in CO. At that extreme altitude, the engine needs more advanced timing (bring a timing light) and extra air (crack open a small filtered vacuum leak bleed). Experiment.
Ok.... I'll shut up now. Just thought I'd throw in a dash of preventative techy for the next guy planning on heading up to the nose bleed zones.
A note on altitude...
The engine cooling system is a sealed system and the pressure it reaches (12-15 psi depending on the cap) is independent of the atmospheric pressure or altitude. The cooling system maximum pressure is governed by the spring pressure of the radiator cap and nothing else.
At sea level or at 13,000 feet, the pressure inside a hot engine cooling system is exactly the same. That being so, the coolant boiling temperature inside the engine is exactly the same at sea level as it is at 13,000 feet (or in outer space for that matter).
The overheating that some engines experienced (probably the 2F carbys?) at extreme altitude may not have been caused by cooling system malfunction unless the radiator or cap was faulty, it was likely because of wrong air/fuel mixtures (too rich) and ignition timing that was too retarded for the oxygen depleted atmosphere at that extreme elevation.
Oxygen thin air found at extreme elevations makes the gas mixture burn slower, so the timing needs to be advanced farther than usual at extreme altitude.
Driving up long, very high, mountain grades with the pedal to the floor (often necessary with a 2F) with retarded ignition timing and out of whack fuel mixture is going to overwhelm any cooling system after a while. Too much of the heat of combustion gets absorbed into the cylinder walls instead of being converted to efficient piston downwards force. If the timing is too retarded, (because of extreme altitude) the late burning flame in the cylinder can actually be blown out the exhaust ports... which overheat the exhaust valves.... and can warp them. Aka burnt valve.
The HAC system in the 2F FJ60 isn't tuned for the extremes in altitude (13,000 feet) that are found in CO. At that extreme altitude, the engine needs more advanced timing (bring a timing light) and extra air (crack open a small filtered vacuum leak bleed). Experiment.
Ok.... I'll shut up now. Just thought I'd throw in a dash of preventative techy for the next guy planning on heading up to the nose bleed zones.
4Cruisers
SILVER Star
I advanced my timing to 10* BTDC when I installed the FJ60 electronic ignition in my '76 FJ40, with original 2F, as I live at 7,240 feet. I also installed a smaller primary main jet when I rebuilt the carburetor. I had no real noticeable power loss or engine overheating issues on the entire trip, including the high passes on US 550 or the 12,000+ to 13,000+ passes on the 4WD trails around Ouray and Silverton. I may experiment a little more on the timing advance.
rhah
Admit it, your cruisers jealous
Day 2 black bear pass
