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Thread: Engine timing

Discuss the Austin Healey Sprite and the MG Midget. Two different but similar cars sometimes referred to collectively as the Spridget.

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    Engine timing

    So, fully rebuilt 1976 1500 with a full complement of factory emission control garbage attached. The owner wants it stone stock. Factory time is 2 degree ATDC at idle. The engine starts instantly, idles beautify, and has the power band of an old tractor. The owner says that is how it has always felt.

    Question -- can I SAFELY bump the timing a few degrees BTC to give a bit of help?
    Bob Buxbaum
    Lee's Summit, Mo.

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    Yoda Trevor Jessie's Avatar
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    Re: Engine timing

    Does it have the original distributor and vacuum advance module?
    _____________________
    1970/2 MG Midget
    Datsun 5-speed
    Future Fuel Injection Turbo Project
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    1958/9 Sprite AN5L/1499
    1275 SuperCharged
    Datsun 5-speed
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    Re: Engine timing

    Quote Originally Posted by Trevor Jessie View Post
    Does it have the original distributor and vacuum advance module?
    Yes. It has a solid state module in the dizzie, vs points.
    Bob Buxbaum
    Lee's Summit, Mo.

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    Re: Engine timing

    At some point they were doing some crazy stuff with the timing for the sake of emissions. IIRC, it was required to keep the stock timing to work with the emissions stuff otherwise you'd get incomplete burn at idle.
    _____________________
    1970/2 MG Midget
    Datsun 5-speed
    Future Fuel Injection Turbo Project
    _________________
    1958/9 Sprite AN5L/1499
    1275 SuperCharged
    Datsun 5-speed
    _________________

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    Re: Engine timing

    Quote Originally Posted by Trevor Jessie View Post
    At some point they were doing some crazy stuff with the timing for the sake of emissions. IIRC, it was required to keep the stock timing to work with the emissions stuff otherwise you'd get incomplete burn at idle.
    I am well aware of the emissions issues. The question still stands -- can I SAFELY bump the timing a few degrees BTC to give a bit of help?
    Bob Buxbaum
    Lee's Summit, Mo.

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    Re: Engine timing

    I do not know the answer. I suspect that bumping the timing might give it a bit of help, but at the risk of damaging the cat or over heating the cat. The 1500 engines have a pretty long stroke and I've always thought of them as just a low rpm high torque engine.
    _____________________
    1970/2 MG Midget
    Datsun 5-speed
    Future Fuel Injection Turbo Project
    _________________
    1958/9 Sprite AN5L/1499
    1275 SuperCharged
    Datsun 5-speed
    _________________

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    Re: Engine timing

    Quote Originally Posted by Trevor Jessie View Post
    I do not know the answer. I suspect that bumping the timing might give it a bit of help, but at the risk of damaging the cat or over heating the cat. The 1500 engines have a pretty long stroke and I've always thought of them as just a low rpm high torque engine.

    Umm .... no cat. Not a California car.
    Bob Buxbaum
    Lee's Summit, Mo.

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    Re: Engine timing

    Only the 1975 cars did not have catalytic converters. My parts book puts the cut off at GAN6-166304

    Does it have EGR valve still in place? What about the anti- run on valve? If those are missing, or are not working, then you are going to need to just tune old school and hope for the best.
    _____________________
    1970/2 MG Midget
    Datsun 5-speed
    Future Fuel Injection Turbo Project
    _________________
    1958/9 Sprite AN5L/1499
    1275 SuperCharged
    Datsun 5-speed
    _________________

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    Re: Engine timing

    I run my 75 Spitfire at 12 degrees before TDC. With a pertronix module. It also has HS 2’s. And it runs great. It’s the same motor. If you are too far advanced you will get pinging under heavy load. Then you will need to back it off a little.
    "Age considers; youth ventures." Rabindranth Tagore
    1975 Spitfire

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