Huge backfire

Discussion in 'General Maverick/Comet' started by wolfheads, Oct 3, 2017.

  1. wolfheads

    wolfheads MadMav

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    After installing the new distributor and coil and new plug wires, I proceeded to crank it up.. On the first try, it just turned over and over and over without any attempt to fire. So I turned the distributor one direction and still nothing. Turned it back the other direction and it turned over and over and then BOOM !!! Huge backfire. I thought I had the distributor marked where # one was relative to the motor and also marked where the rotor was pointing prior to removing the old distributor. I guess I was wrong. I suppose I need to find TDC and go from there. The plug wires are in the correct order. I double checked those.
     
  2. mavdog71

    mavdog71 Member

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    You are going to need find TDC .. The way I have to due it Remove the #1 spark plug bump engine over with your thumb in spark plug hole until air is blown back at that point you are coming up on TDC . Check pointer on at front crank damper and align pointer with TDC on damper . Now find # 1 on distributor and install . At this point you still need to drop into oil pump drive . You still may need to advance or retard distributor to get proper timing.
     
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  3. Krazy Comet

    Krazy Comet Tom

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    Agreed with mavdog...

    If you think it's off only by a tooth, you can bring it up on TDC and look to see where rotor is pointing... If it's anywhere near #1 you may be able to lift dist enough to clear gear, rotate shaft slightly and set it back in place...

    Timing marks can be a bear(or female dog) to see, I've marked mine with white paint...

    [​IMG]
     
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  4. groberts101

    groberts101 Member

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    Pretty easy to be off a tooth during distributor install. Repeated cranking just floods the engine till it goes boom. And too much of that wipes the rings and bore out while contaminating the oil with raw fuel. Easiest fix is to just rotate the housing to reset the rotor at correct phasing ahead of #1 plug. Limitation there would be vac pot contacting the manifold before reaching the optimum initial timing mark.

    I don't mean to come off as a prick here.. but after all the issues you've had so far tuning this motor.. why are you not using a light to verify actual timing numbers?

    I'll also say this. If you screw around hammering on a motor with incorrectly set timing too long, and since day 1 I thought you had ignition related issues, you'll end up hurting the piston decks or ringlands to the point no amount of tuning will set you straight again. This stuff isn't that hard if you break it down into seperate subsystems and use process of elimination to home in on the specific problem.
     
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  5. wolfheads

    wolfheads MadMav

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    I set the #1 piston to TDC and checked where the rotor was pointing and I was off by about 3 spots. Got the wiring corrected and fired it off. Advanced the distributor to the sweet spot for now and took her for a run. The stumbling and hesitation no longer exist. Instantly fires up now. It was either or a combination of the vacuum line stopped up or the distributer was failing.
     
  6. wolfheads

    wolfheads MadMav

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    Not the prettiest, but all new components. Runs great now.
     

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  7. Krazy Comet

    Krazy Comet Tom

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    Hey that's great but with vac cannister all but touching the thermostat housing, it's still off a tooth... It should be pointing directly toward front of car... Also at TDC the rotor should be approx pointing at the LF carburetor stud...
     
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  8. wolfheads

    wolfheads MadMav

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    I agree Tom. As you can see in the image, the #1 position is where indicated by the arrow at TDC. It may be off by more than one tooth. But at least it starts and runs good. I'll get the position corrected. Also I'm getting a smaller breather. The one on there now is sitting on 2 of the plug wires on the back of the distributor. Could cause an issue later on.
     

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  9. Krazy Comet

    Krazy Comet Tom

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  10. groberts101

    groberts101 Member

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    Easy to correct that hot mess by retarding the distributors currently clocked position and swapping plug wires to their new positions.

    And I've never been a big proponent of smaller od air filter bases. Hard enough as it is for air to make all the sharp turns and twists. Better alternative is to use a 1/2" spacer. Added bonus is reduced charge temps.
     
    Last edited: Oct 7, 2017
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