[Question] Adjusting carb for altitude
+ Reply to Thread
Results 1 to 3 of 3

Thread:
Adjusting carb for altitude

  1. #1
    Senior Member
    Join Date
    Mar 2009
    Posts
    3,356

    Default Adjusting carb for altitude

    Well, I may take my boat up to Antelope lake in the Northern Sierra at 5000 feet altitude...Do I need to adjust the carb(Lean it out a bit) for that altitude, or will it run ok? I have an Edelbrock 750 on a slightly improved 460 w/Stealth manifold.

    I normally go up to Trinity at 2370...But the Bur'O'wreck has drained it each drought year, so while Shasta is almost full, and Oroville is up almost 200 feet, Trinity is still down 100 feet...And they are probably going to dump most of it again this year....They claim they are supporting the fish in the Trinity/Kalamath system, but 90% of the water goes thru a tunnel to the Sacto river.....
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	1f6dad5b218cae21dccdc36e8391a671.jpg 
Views:	68 
Size:	21.0 KB 
ID:	864337   Click image for larger version. 

Name:	img_7956-copy.jpg 
Views:	33 
Size:	29.2 KB 
ID:	864345  
    Last edited by cvxjet; 03-16-2016 at 01:31 PM.

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member jetboatperformance's Avatar
    Join Date
    Dec 2007
    Location
    Atascadero Calif
    Posts
    7,463

    Default

    Very little you can do with that carb, look into a Edlebrock tune up kit , might help , Plug readings will be a good place to start ....


    https://www.google.com/webhp?sourcei...20tuning%20kit

  4. #3
    Or Seth, either one Budweiser's Avatar
    Join Date
    Dec 2007
    Location
    Tower Park Resort, Lodi, CA
    Posts
    3,270

    Default

    Edelbrock AFB style carbs are as tunable as a standard Holley and much easier to make changes on. Some of the more recent offerings from Holley and the aftermarket do add additional tuning capabilities, but an AFB is quite simple and effective in any N/A application that a standard Holley suits.

    Here's their input on your question and a link to the owners manual.

    High Altitude
    Altitude has a direct effect on the operation of most carburetors. As the altitude increases, the air becomes less dense so a carburetor, originally calibrated at low altitude, delivers too much fuel and the engine runs richer. If the preceding tuning procedure is performed on an Edelbrock Performer Series carburetor, a proper high altitude calibration will result. If the vehicle was calibrated at lower altitude, however, and is to be driven at high altitude temporarily, it is not necessary to repeat the complete calibration procedure. Instead, use the rule of: “2% leaner per 1500 feet” and the Calibration Reference Chart for your model carburetor. For example, with a #1405 at baseline calibration (location #1 on the chart) and intended operation at 6000 ft. altitude, you would want 6000 divided by 1500 x 2% = 8% leaner calibration. That would be location #24 on the chart which would require only a rod and jet change.


    http://www.edelbrock.com/automotive/...ers-manual.pdf
    Last edited by Budweiser; 03-16-2016 at 02:55 PM.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in


Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95