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  1. #1
    pasvorto1's Avatar
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    Default Electronic ignition

    The car is sounding like it needs a tune up. I am thinking that this may be the time to switch over from points to electronic ignition. Are there any recommendations for a 78 L48? I assume it is a job that a shade tree mechanic can do.
    1978 SA
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  2. #2
    Member Jack's Avatar
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    Quote Originally Posted by pasvorto1
    The car is sounding like it needs a tune up. I am thinking that this may be the time to switch over from points to electronic ignition. Are there any recommendations for a 78 L48? I assume it is a job that a shade tree mechanic can do.
    I dunno if yours has been changed ... BUT ... beginning model year 1975 the "electronic" HEI (high energy ignition) distributor was standard on all vette ... points saw their last use in vette model year 1974.

    HEI has large distributor cap and its spark plug wire terminals actually look like spark plug's terminals ... and it has only 8 wires attached to cap (points cap has 9) ... HEI measures about 1.75" between adjacent sp terminals. 1978 vette should have HEI from factory.
    JACK

  3. #3
    pasvorto1's Avatar
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    I willl have to go take a look. I willfeel pretty stupid if it does..
    1978 SA
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    78 has HEI

  5. #5
    pasvorto1's Avatar
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    I guess I can scratch that "upgrade" off my list.
    However, it has started running 'rough' lately. Maybe the HEI needs to be looked at.

  6. #6
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    HEIs work really well and are very dependable. With over thirty-five years experience of repairing cars & trucks I have never run into a GM HEI that caused a vehicle to run rough or idle badly.

    Check these items first:

    All vacuum hoses and connections. They need to be tight and the rubber in good condition.

    Carburetor bolts need to be tight. These are the four bolts that mount the carburetor to the intake manifold.

    While engine is running, spray carb spray around carburetor base and along the intake manifold where it meets the valve covers. If the engine speed changes while doing this, it means that you have a vacuum leak where you have sprayed. The gasket in question needs to be replaced.

    These are the most common and basic problem areas.

    Let me know what you discover.

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    Duh, I forgot to mention one item.

    Inspect the inside of the distributor cap. If you see any carbon tracing from one contact to another, the cap and the rotor should be replaced. This carbon tracing would cause the engine to run poorly.

    Hope this helps.

    Save The Wave!
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  8. #8
    pasvorto1's Avatar
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    I will check them out after work tomorrow. Thanks for the suggestions. I decided not to sell it (and buy a 64 Galaxie 500 XL). So now I have to get it back to 'smooth'.
    1978 SA
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    Sell a Vette for a Ford? I think you made the right choice (not to sell). Although the Galaxie is definitely one of the hotter Fords. If I was to go with the blue oval that's what I'd get. But I wouldn't...ever.

  10. #10
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    Glad to hear you are keeping the Vette.

    I had a '66 Ford Galaxie 500XL. A beautiful car. But can't hold a candle to any Vette.

    Let us know how you progress.

    Save The Wave!
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  11. #11
    pasvorto1's Avatar
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    I went exploring after work today. It definitely has HEI (dummy). I removed the cap. The contacts are worn as is the tip of the rotor. I think it should be replaced. I assume the coil comes with it as one unit? I was fooling around with the choke and started the car. While I was checking the main butterfly position, I noticed one of the plug wires was arcing out against the exhaust shroud. I shut it off. Forgive my 'bubba-ness', but I wrapped the offending areas on the plug wire (there were 2 of them) with electricians tape. The car seemed to smooth right out. So, new dist cap and new plug wires. I think I will also get some plug wire hangers. I did find one flexible tube (about 1/8" in diamter) that connects to the very front of the carbeurator was bogus. It has a cap that goes over a nipple on the front of the carb. The cap was split, so the hose had to be leaking. Again, going "Red Green", I grabbed the electrical tape until I can get a new cap for it. It goes top the firewall. I have absolutely no idea what it is or what it does. Since a previous owner removed most, if not all, the pollution control stuff, there are a number of nipples with no hoses connected to them. It will take a bit of research on my part to identify all of them and determine if I need to do anything about them.

    Thanks for all the help so far.

    Now, about that clunking noise in the left rear (see my post).
    1978 SA
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  12. #12
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    Ok, now that you found the problems.
    The cap will be replaced and the top of the cap has 2 screws that come off the expose the coil. Swap the coil out to the new cap.
    The 1/8" hose that goes to the firewall is a vacuum hose for the heater selector. It is connected to a lower port on the carb. that supplies manifold vacuum, and is not a ported or modulated vacuum source.
    Pete

  13. #13
    pasvorto1's Avatar
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    What does the vacumm hose for the heater selector do? What would be the symptons of it 'leaking'?
    1978 SA
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  14. #14
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    The vacuum hose for the heater selector causes the different doors in the heater box to open and close properly. They enable the air to be diverted to the different vents: defroster, heat at floor, a/c vents.......if the air does not come out of the correct vent, that would point to the vacuum hose leaking.

    Your electrical tape fix is a great one! See what I said previously about the dependability of the HEI system? All it takes is a little investigative work and you came up with several problems. Sounds like you have everything pretty much figured out. Congratulations!

    Save The Wave!
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  15. #15
    pasvorto1's Avatar
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    New dist cap, new rotor, new plugs, new plug wires. S-m-o-o-t-h....
    1978 SA
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