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spark plug gap

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Old Aug 8, 2012 | 06:33 PM
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Default spark plug gap
I am sure this question has come up before.
But here it is I have a 1975 corvette coup 350 L 48 engine.
Recently I went to buy spark plugs for it at Auto Zone . They gave me Ac Delco R44tx plugs . i think these are correct plugs for car. Now they are gap at . 060 thousandths. The manual says they should be .035 . Car does run good ,little rough at idle . Should I try the .035 and see if it runs better.
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Old Aug 8, 2012 | 07:02 PM
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From: Working on the car NY
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Without me looking anything up, .035 is usually reserved for non-HEI (points type) ignition. .060 is for HEI.
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Old Aug 8, 2012 | 07:19 PM
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Dont know what manual you are looking at but the correct plug is the R44TX gapped at .060.
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Old Aug 8, 2012 | 08:13 PM
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Modern cars with modern high-energy systems may need .060" gap...but I thought the early GM H.E.I. systems specified a .045" gap on the plugs.
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Old Aug 8, 2012 | 08:34 PM
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I know under my hood on the sticker behing MC it says .45. She was an L48 at birth.
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Old Aug 8, 2012 | 08:44 PM
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1975 GM spec was 0.060". They had issues with that large of a gap though and by '76 they revised it down to 0.045".
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Old Aug 8, 2012 | 11:26 PM
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Yeah. .060" gap was "wishful thinking" by GM....
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