Does altitude matter?

[BigDaddyZ]

I live at 6000' and regularly drive my 1.7 F.I. into the mountains (as high as 10,000'). Where should I set the timing to get the most out of the switchbacks?

[Tobra]

altitude will not impact ignition timing, stock timing for you

you are down on power because there is less oxygen to burn, if you want to get more out of the switch backs, you want a bigger motor, or even better a turbo. Turbo will be far less impacted with high elevation than all motor

[byndbad914]

that isn't true - you tend to be able to run more timing at higher elevations. For instance, I would run 36deg advance in my Mustang when I ran at sea level in Long Beach to get the best mph out of the car (and had large jets as I had air to burn fuel). When I would go to Palmdale on a hot day, the altitude would be adjusted to say 3500ft. I would jet down a few sizes and run as high as 42 deg total advance to get max mph.

Now, that said, I would set the timing based on best power at 6000ft, nothing higher. The reason is if you set if for any higher altitude, then when you are on the throttle at the lower part of your journey you will be detonating the engine and essentially trying (or worse, actually) to melt pistons/heads.

[byndbad914]

a quick for instance with a simple google search of ignition timing altitude adjustment. Oddly enough, at 4K alt they adv 7deg on the car and I was 6 deg on mine for a 3500 ft calibration

On the above 1984 Eagle six-cylinder and four-cylinder models originally certified for operation at altitudes below 4,000 feet that are being operated above 4,000 feet, the ignition timing must be advanced 7" and engine idle speed reset. In addition, a jumper wire must be added to the MCU circuit to activate the altitude compensating circuit in the MCU.

1. Move the carpeting away from the passenger front seat toeboard to expose the MCU harness.
2. Untape the two-terminal connector from the MCU harness.
3. Connect jumper wire, 318 6890, to the two-terminal connector and reinstall the carpet.
4. Advance ignition timing 7" from the setting indicated on the original Vehicle Emission Control Information label in the engine compartment and reset engine idle speed to the setting indicated on the same label.
5. Install Vehicle Emission Control Information Update label, part number 8983 100 009, next to the original label.

These adjustments apply to the indicated 1984 AMC six-cylinder automatic and four-cylinder manual/automatic models originally certified for principal use at altitudes below 4,000 feet. Refer to the Vehicle Emission Control Information label to identify these vehicles.

NOTE: Whenever these vehicles are returned' to operation at altitudes below 4,000 feet, the MCU circuit jumper wire must be removed, the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control information Update label removed.

On 1984 Eagle six-cylinder automatic and four-cylinder manual and automatic models originally certified for operation at altitudes above 4,000 feet that are being operated below 4,000 feet, the ignition timing should be retarded 7 " and engine idle reset. In addition, the MCU circuit jumper wire must be disconnected and taped to the MCU harness.

[Tobra]

You can't rejet a D jet car and the engine management on it is very primitive, especially compared to an '84 anything.

I would not run timing much or any advance beyond the factory specs, as I have seen more than one melted air cooled motor that was running too lean and/or too much advance. Riskvs benefit to me, but I am very risk averse, guess you can try it out and see what happens, might want to run premium fuel if you are going to go there.

[BigDaddyZ]

Wouldn't turbo charging generate as much if not more heat?