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5.0 and 5.7 Discussion, 1990 Brougham 307 V8 in Cadillac Engine Technical Discussion; Originally Posted by N0DIH If blown, the carb'd 307 won't stop running, it will run pig rich, but won't stop ...
  1. #16
    MadCaddie69's Avatar
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    Re: 1990 Brougham 307 V8

    Quote Originally Posted by N0DIH View Post
    If blown, the carb'd 307 won't stop running, it will run pig rich, but won't stop running. If the HEI fuse, yes, it will stop running. But ECM fuse it will go rich and fixed to base timing (10 degrees or so)

    Oh, and IIRC on the 307, the dizzy turns the opposite way as a Chevy, so make sure the wires are going around the same.

    http://www.oldsmobility.com/tuneup.htm

    The rotor turns CCW, and the wires should be 1-8-4-3-6-5-7-2 going also CCW. Chevy it is CW and the rotor turns CW.

    This is from the side of the cam the dist gear sits.

    Easy way to check. Pull #1 plug, pull cap off. Stick finger in the plug hole lightly, have someone bump over engine till you feel compression, note where rotor is pointing, that is where #1 is.
    Yeah. We did that. We bumped it, checked over the plug wires, and everything. The old timing chain was definitely worn out. However, when I tried to start the car the first time, I saw a big spark come from the distributor. Any clues? If anything, after what you wrote, I'm thinking the HEI fuse must've blown. Other than that, it should have started. At least I would think so. I'm going over there tomorrow to check it out.

  2. #17
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    Re: 1990 Brougham 307 V8

    I have had on 2 instances the ignition module pop when the fuel system crapped on me (fuel pump once and float other). Makes NO sense, but that is what it was.

    Are you getting ANY spark?
    1. To get spark on a HEI you need the coil to have power (ensure the BAT lead to the cap has +12v when ignition is on.
    2. The reluctor or pickup coil needs to be working. IIRC, you can check it with a meter on voltage scale, pretty low settings, and crank engine (or some other way to spin the rotor). It should go up and down, might work on AC scale better. Same purpose as the points have on the older engines.

    You need fuel, spark and spark at right time. IIRC you can physically remove the ECM and it will run.

    Quote Originally Posted by MadCaddie69 View Post
    Yeah. We did that. We bumped it, checked over the plug wires, and everything. The old timing chain was definitely worn out. However, when I tried to start the car the first time, I saw a big spark come from the distributor. Any clues? If anything, after what you wrote, I'm thinking the HEI fuse must've blown. Other than that, it should have started. At least I would think so. I'm going over there tomorrow to check it out.

  3. #18
    MadCaddie69's Avatar
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    Re: 1990 Brougham 307 V8

    Quote Originally Posted by N0DIH View Post
    I have had on 2 instances the ignition module pop when the fuel system crapped on me (fuel pump once and float other). Makes NO sense, but that is what it was.

    Are you getting ANY spark?
    1. To get spark on a HEI you need the coil to have power (ensure the BAT lead to the cap has +12v when ignition is on.
    2. The reluctor or pickup coil needs to be working. IIRC, you can check it with a meter on voltage scale, pretty low settings, and crank engine (or some other way to spin the rotor). It should go up and down, might work on AC scale better. Same purpose as the points have on the older engines.

    You need fuel, spark and spark at right time. IIRC you can physically remove the ECM and it will run.
    Ok. Check this out. The car is getting spark, fuel, and compression. So why won't it start? Probably doue to the fact that the gas in the car is watered down after sitting in the tank for over a year. So I'm thinking drain the gas out, adding octane booster in the tank with some fresh 93 octane. What do you think?

  4. #19
    N0DIH's Avatar
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    Re: 1990 Brougham 307 V8

    I have had gas sit for 2-3 years and do fine. Unless it gets contaminated with water, it should be fine.

    Try this, be very careful, but run it on carb cleaner to start. Gumout is wonderful stuff.

    Also, timing, if too far off will be a bear to start, if impossible. Bump over to TDC, (compression stroke on #1) pull cap and verify rotor is pointing directly AT #1. It should be IIRC 10 degrees off (base timing). If pointing somewhere else, that is your issue. I wouldn't mess with the fuel just yet unless you suspect contaminated.

    Pull the plugs and verify they are not wet enough they won't start. Flooded engines won't start well either. WOT and cranking is clear flood mode (yes even on a Q-Jet!) but it will start once it can, so be careful not to overrev it once it starts.

    Is spark hot? Nice and blue, not yellow and weak?

  5. #20
    MadCaddie69's Avatar
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    Re: 1990 Brougham 307 V8

    Quote Originally Posted by N0DIH View Post
    I have had gas sit for 2-3 years and do fine. Unless it gets contaminated with water, it should be fine.

    Try this, be very careful, but run it on carb cleaner to start. Gumout is wonderful stuff.

    Also, timing, if too far off will be a bear to start, if impossible. Bump over to TDC, (compression stroke on #1) pull cap and verify rotor is pointing directly AT #1. It should be IIRC 10 degrees off (base timing). If pointing somewhere else, that is your issue. I wouldn't mess with the fuel just yet unless you suspect contaminated.

    Pull the plugs and verify they are not wet enough they won't start. Flooded engines won't start well either. WOT and cranking is clear flood mode (yes even on a Q-Jet!) but it will start once it can, so be careful not to overrev it once it starts.

    Is spark hot? Nice and blue, not yellow and weak?
    It's the carburetor. It's clogged up.

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