High elevation tuning.

[73c20jim]

I found out that all engine tuning specs are for sea level.

I'm at 4800 feet. All my driving is at this level, give or take a few hundred feet.

How much vacuum do I lose at this elevation?
ANSWERED: 1 inch of vacuum lost for each 1000 ft of elevation. I will be 4.8 inches of vacuum low.

How much more timing advance do I need? Some say bump it from 12 to 14.
ANSWERED: One degree advanced for each 1000 feet of elevation.

What else does altitude affect in tuning?

Truck is carburated with HEI ignition.

Do you agree with these answers.

 

[gotyourgoat]

Unfortunately don't have any answers but am interested in hearing some as I'm about half your elevation.

 

[MisterB]

Altitude definitely effects tuning. I moved from 5,400 feet to 2,000 feet, and my '69 Chevy truck ran like crap until I hooked it up to a vacuum gauge and dialed it in.

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[WFO]

Smaller jets for higher altitude, since there is less air for the mixture.

 

[Raybo135]

Smaller jets for higher altitude, since there is less air for the mixture.

I have Edelbrock E-Street EFI on a 400ci. I am at 5400+. What should I set my AFR to? I have been looking for an answer to that for almost a year. My truck is getting horrendous gas mileage and it seems to be running crappier. Any suggestions?

 

[WFO]

I have Edelbrock E-Street EFI on a 400ci. I am at 5400+. What should I set my AFR to? I have been looking for an answer to that for almost a year. My truck is getting horrendous gas mileage and it seems to be running crappier. Any suggestions?

Sorry, I really don't have a clue about these after market EFI systems.

O2 sensor maybe?

 

[Raybo135]

Sorry, I really don't have a clue about these after market EFI systems.

O2 sensor maybe?

I will check that out. Im not too sure of the guys that installed it. Thanks.

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