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| | | | Joined: Apr 2009 Posts: 192 Shop Shark | | Shop Shark Joined: Apr 2009 Posts: 192 | Just got it, put high octane in runs great just want to be sure? Thanks | | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy RAK, that would depend on the engines compression ratio, anything above 9 to 1 would probably require it, basically the higher perfomance engines. Interestingly as an engine gets older, and carbon builds up in the combustion chamber, the compression ratio rises, and the engine will start to "ping" on regular grade gas, but not on premium. The 327 did not come out until 1962, so I'm assuming you or someone else swapped it into your truck. | | | | | Joined: Apr 2009 Posts: 192 Shop Shark | | Shop Shark Joined: Apr 2009 Posts: 192 | Yes it was swapped about 15 years ago and rebuilt. Has maybe 3000 miles on it.The high test I put in seems fine so I'll just stay with it ? I guess I could try the medium grade but why fool around to save a few pennies? Thanks for the thoughts. | | | | | Joined: Jul 2008 Posts: 413 Shop Shark | | Shop Shark Joined: Jul 2008 Posts: 413 | I have a 68 327 in my 72 chevelle I only run the higher octane gas in it. It seems to run its best with it. | | | | | Joined: Jan 2008 Posts: 4,961 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,961 | Detroit got into a horsepower race in the mid 50's which didn't end until emissions laws started in 1971. Oil companies had to keep up with the race and research octane ratings went well over 100. Of course the oil companies had tetraethyl lead at their disposal. Many vehicles were designed for high octane fuel and don't preform well without it. And as mentioned earlier, carbon buildup raises the compression ratio. | | |
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