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Just got the 66 Lemans. In 66 they still had Leaded gas. What gas should I be putting in my 67 400 GTO tripower? I knoiw they used to have a lead additives to put into the tanks when they went to unleaded gas. Is this still a good aproach? or is the unleaded ok to run?
 

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the lead is not a factor as much as the octane of today camel piss is. really depends on how long ago and how your engine was re-built and what head casting you have (Compression Ratio). optimal comp. of 9.5:1 to be able to run the swill they pass of as pump gas (89-93). out of the factory most of the pre 71' cars were more like 10.5:1 and would require 96+ octane in today's gas to ward off detonation. If it was rebuilt recently it may have had pistons dished or have larger chamber cylinder heads swapped to it to lower the compression. What gas are you running currently? Do you hear any spark knock (detonation), especially under load (going uphill)if you do you need to run a higher octane.
 
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