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I have a 83 SC ROW with only one vacuum line on the distributor. I sometimes hear it knock, usually on hot days . It's set at 5 BTDC and gets up to about 35 at 6000 rpm. As stated before, here in CA we only have 91. I put in 100 on occassion, and that seems to do the trick. But at 6 bucks a gallon, I can't do it all the time. Any advice wouid be appreciated. thank you.
Demetri
Your engine has higher (9.8:1) compression and was tuned to run on 98 RON with 25 BTDC max ignition timing. 98 RON is around 93 CLC octane fuel. Unless you are a magician, you can't run the engine on lower spec fuel with 10 degrees more advance, than the factory could. The answer is you need to raise the octane of the fuel or reduce the timing. Your distributor should only give 20 degrees of mechanical advance, so I would first check it is the right part number, then question your measurements. You also want to check the AFR at WOT to make sure it is not too lean. The only ways to lower the octane requirement of your engine is to improve cooling, lower the intake air temp, or get the oil mist out of your intake.
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Paul
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