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Altitude Adjustments

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazer79, Jun 24, 2000.

  1. Blazer79

    Blazer79 1/2 ton status

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    Location:
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    I have a new Edelbrock Q-jet #1902 on my Blazer. I managed to adjust it to run fine, but I'm at 5000 above sea level. When I travel to my grandparents (650ft ASL) the Blazer performes MUCH better. It feels as if I had rebuilt the engine or some other improvement like that.

    I wrote to Edelbrock's Support, and they answered this:

    5000 feet you are effecting the complete engine and the way it performs. If you notice when they drag race in Denver they don't go as fast as they do Pomona Ca. Due to air conditions. What you described is normal.

    I thought there was something I could do about it. The Doug Roe book on Q-jets says I could rejet it to be leaner. Any ideas?


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  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    You are near a mile above sea level. I bet you also feel much stronger at the your grandparents because there is more air at sea level. Edlebrocks responce is correct and there is nothing you can do. leaning will help some to adjust for the lack of air but be carefull how much you lean because then it will get into a detonation problem when you go to your grand parents. The only other thing you can do is go FI and it will automaticly adjust for altitude.

    Diging it in the dirt with my K5's
    Grim-Reaper
    http://grimsk5s.coloradok5.com/
     
  3. chaka73

    chaka73 1/2 ton status

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    Hey tocayo the other option is move into your Grandparents house talk to ya later.

    check out my new site, thanks Steve!
    http://chaka73.coloradok5.com
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Hey Grim: Do you have any idea if a 6.2 will auto adjust for altitude changes? It may be my imagination, but I swear my diesel runs better at lower altitudes. I realize that a diesel's performance relies heavily on air intake, and the lower I go, the more air I get. Or is there a way to manually compensate for high altitude? BTW, Canmore sits at around 1220 metres above sea level, which is around 4000 ft.
     
  5. getsome

    getsome 1/2 ton status

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    I live in Denver and when I replaced my Q-jet with a Edelbrock 1406 I found out that it comes jetted for sea level. I don't know if their is some kind of cross refferance but if you go with 95 pri 92 sec jets and 70X47 rods it will run fine untill you get back to sea level.

    Getsome
     
  6. Blazer79

    Blazer79 1/2 ton status

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    Yeah, It would be a dream come true to move out there. Out in the country with plenty of trails, no phones ringing and 100% pure air. Someday I'll retire and live over there.

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  7. dumbfounded

    dumbfounded 1/2 ton status

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    The higher you go the less dense the air is so you need less fuel to maintain the proper air/fuel ratio. There isn't a way to get around it either. Same with a diesel. If you had a turbo and could increase the boost it would compensate, but haven't seen many turbo blazers. So suck it up or move to florida......

    Wasn't me.............
     
  8. Burt4x4

    Burt4x4 3/4 ton status

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    I would have too say that I had a similar issue when heading up the the slops to do some skiin I would loose the power so on my Edle Q-jet 1901 I replace the Primary metering rods with,hmmm, I can't remember witch ones,hmmm,anyway I can find out I think I went from 30 to 40 anyway IT DID HELP and now I have the best of both worlds! I live in the California valley and my performance is the same as before and I still loose a bit of power when I head up the the Mtns but not nearly as much
    hope this helps let me know if you what the meetering rod #s that I switch too???!!!

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  9. dpearson

    dpearson Registered Member

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    Hey Getsome,

    I have the edelbrock 1407 and when I hit a bump it floods out, I was reading that the Q-Jet is better for offroading, I was just wondering why you went the other way. Thanks
     
  10. Blazer79

    Blazer79 1/2 ton status

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    I thought you had to change the jets, not the rods. I'm currently running the .069 jets and 36B rods that came with it. Your 1901 also had these when new. Edelbrock sells 37, 39, 41, 43, 45... rods. Any of these ring a bell? At what altitudes are you usually driving?

    I read at Edelbrock's website that the #1901-1904 should not be adjusted unless driven on high altitudes. I wonder why their tech support didn't mention anything about rejetting/rerodding.

    Thanks for your help.

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