Big bloc and unleaded fuel
12-05-2007, 04:39 PM
#5
Safety Car
Several studies report that unleaded fuel in the older lead gas engines does no harm to the valve seats or other parts. I have run unleaded 94 in my 70 L46 for several years.
12-05-2007, 07:54 PM
#6
Race Director
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You can run unleaded in ANY of the old cars without a problem as long as you are NOT pulling a trailer. Only under really hard working conditions do you run the risk of exhuast valve errosion without lead for lubriacation.
So yes it will not hurt your bigblock.
So yes it will not hurt your bigblock.
12-05-2007, 08:18 PM
#7
Burning Brakes
I use premium unleaded 96% and also add flashlube. I realize I don't need to with hardened seats but I want to give the original engine every possible chance at long life. Found that she didn't like running on regular unleaded as much and NOT Ultra, I'm no expert but it seemed to burn too clean.
12-06-2007, 08:59 AM
#8
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2023 C3 of the Year Finalist - Unmodified
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I have been running unleaded premium in my 61,65 and 68 big block for years with no problems. The notion that without hardened valve seats unleaded fuel will cause problems is a long perpetuated MYTH. The only difference I noticed when they did away withh leaded fuel was that my spark plugs burned cleaner and lasted longer. As far as octane: An octane rating of 93 today is similar to a high 90's rating back in the 60's.
