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Thread: AMC Engine Help

  1. #1
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    AMC Engine Help

    I have a 1968 AMC Javelin with the original 343 engine. The only changes made to the engine is the heads were ported,larger cam, aluminum intake. This engine stock was supposed to be timed with a setting of 0 degrees, (TDC). The car has never idled correctly since it was purchased. I have spoken with Edelbrock about the gasket set up for the intake to no avail. There is still a vacuum leak somewhere. Has anyone ever ran across this? I know AMC is a lost breed but this little car is a blast when it works right. I have tried Right Stuff, Permatex silicone and still it seams to have a vacuum leak. Any ideas on timing with a bigger cam? It is a 520 lift hydraulic, nothing special. Just been working on this for some time and it is about to get sold. Any help would be greatly appreciated. Thanks. Cliff.

  2. #2
    Senior Member RACING JUNKIE fla1976's Avatar
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    Does it have vacuum advance? Check for bad vacuum canister at distributor.

  3. #3
    Senior Member RACING JUNKIE fla1976's Avatar
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    Check vacuum modulator if it has automatic trans and associated lines.

  4. #4
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    Car is 4 speed. I have not checked the advance. The car will idle for a few moments then die.

  5. #5
    Member JUNIOR BUILDER jayvee34's Avatar
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    Sounds like it is retarded to me. Try advancing it a little at a time until it
    runs right, and idles. I had about the same problem with a Chevy engine. My timing
    tab was way off. Also you might find true TDC and check your timing tab to see if
    it is on the TDC mark.

  6. #6
    Member JUNIOR BUILDER jayvee34's Avatar
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    Don't look like Cliffy is going to tell us if he fixed his problem, or if any of
    the possible solutions we thought of that might of helped.

  7. #7
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    Sorry for the no response but have worked 29 days straight and just have not had time to get to work on the car. I did find TDC and it seems to be right on with the tab. Tried advancing the timing and it will idle fine it seems like until it warms up then it dies and will not stay running. It hesitates bad when you apply any throttle like the distributor is not advancing. I tried a vacuum pump on the advance and it pulls the advance in the distributor. I am wondering if because of the bigger cam and the duration if there is enough spark with the old points. I pulled all the plugs and did a leak down and all the cylinders are at 94 to 96%.

  8. #8
    Member JUNIOR BUILDER jayvee34's Avatar
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    If you have another coil, and you know it is good, try it. Points if set properly
    (and plug gap) with a good coil should not be a problem with your cam. Coils will
    heat up and break down causing the engine to shut down, and also cause hesitation
    when revving. If your coil requires a ballast resistor and you are not using one
    will cause a coil to heat up and break down.

  9. #9
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    I have a new MSD coil and just installed a new distributor, magnetic pick up, with new wires. Also removed all of the vacuum lines except for the brake booster. I set the timing again to around 14 BTDC and it will idle now and stay running. It still has a bad hesitation when the throttle is opened and it smokes out of the right exhaust pipe. Is it possible that the intake is still not sealed to the head? Edelbrock calls for a paper gasket along with the metal intake gasket when installing their intake on a stock head. When I spoke to them directly they said do not pay attention to the instructions and use only the metal gasket with RTV. Is it possible I am being stingy with the RTV? Should I just use a larger bead?

  10. #10
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    I removed the intake, installed a new metal gasket, still is hard to set the idle and now it is smoking out both headers. The car never idled correctly but never smoked. Starting to become a little baffling. Any had any luck with paper gasket only?


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