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Thread: 455 tweeking for altitude

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  1. #1
    m14dan is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Car Year, Make, Model: 73 electra, 84 c-20, 91f-150 4x4

    455 tweeking for altitude


    My wife Is driving a 73 electra show car, yeah I know why maintain an electra but It is a nice big safe car, It has a 455 with edel intake and holly 750 and the original points ignition. It was running perfect when we lived at sea level but now we are at 3500 feet and after recalibrating the carb I am still getting some black smoke when I show some kid what cubic inches can do to his little honda. I have gone down 3 sizes on the primary jets and gone to a brown spring on the secondary wich is 1 step stronger than original. Secondarys are still rich though and I don't want them to come on too much higher. also the primary mixture screws are only about 1/2 turn open to get a proper idle with every thing set to spec. Is this time to drill holes in the primaries? I hate doing that. I have tried cracking open the secondary some but it didn't help so I put that screw back where it was. It does idle great so maybe I shouldn't even worry about the idle circuit.
    Also I have been thinking about replacing the point distributer with an electronic. Any recommendations? Mallory makes a comp 9000 but I have no experience with them. It isn't a race car but is a premium gas, high horsepower,big boat of a car and I hate it when my wife calles and says she can't get it started because it is raining. Points are weird like that sometimes. Original HEI's are rare for it and would have to be from a car a couple years newer. Most of them went to the crusher long ago so that is almost impossible. I am a mechanic and have absolutely no faith in rebuilt ones from the local parts stores either. If anyone has any hints or ideas please let me know.

  2. #2
    Dano78's Avatar
    Dano78 is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Car Year, Make, Model: Fords.. All pre-'78

    Dan- I use Pertronix on all my stuff with an exception to my truck which I drive every day had Accel points. The Accel points have never given me any trouble whatsoever and I have well over 18,000+ miles on them and i've never needed to adjust then since initial installation. They've been in my truck for about 2 or almost 3 years now. First time I've ever used Accel points before. I hear ya, I normally have been using Niehoffs or the other brands and they have been nothing but a PIMA. I'm definately impressed with the Accel points and will continue to use them.

    I have Pertronix units on everything thing else and have installed them in sever other friends' cars and customers' cars. I swear by them. Never had one fail on me yet. But like anything electrical I still carry a set of points, just in case... I have a pertronix unit on my race car and am running a Mallory Promaster coil on it. Seems to work like a champ. My bro has had his in his maverick since the dayhe could drive and that was about 6 years ago. Never a problem and all we do is just replace the "factory stock" points style cap and rotor as normal wear occured. Pertronix is DEFINATELY the way to go!

    As far as your richness problem with your carb, look at your other post. - Dano
    Dan Ouellette
    '25 T C-Cab
    '47 Ford Coupe
    '53 Ford Crestline
    '53 Ford Mainline
    -And 8 more Fords and 2 Mopars

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