i know this isnt really related to the slant six engine, but I was wondering if anyone knows what three octane fuels you could at a gas station back in the 60's and 70's....i wasnt sure if it has changed at all.

There were more then three octane ratings in the 60's. Sunoco had two fuel tanks, one with what they called "190" and another with "280". The pump had a dial, which was set for the octane you wanted and the pump mixed the 190 and 280 in the proper ratio. The highest rating was 100, Hess also had "101" octane. One thing to remember, though, the octane rating was measured differently, back then. It was measured, using the "research" method. Today, gasoline is rated using an average of the "research" and "motor" methods, which gives a lower rating.
By the way, octane is only one of many factors, that determine if a gasoline is suitable for a particular engine. That is why VP has this many different fuels. http://www.vpracingfuels.com/vp_01_fuel ... E#unleaded

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Note also that the AKI method [(RON + MON) ÷ 2 ] is only used in North America. Elsewhere in the world, they still use only the RON octane ratings, so their octane numbers are higher for any given level of antiknock performance.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks, Dan. I forgot to mention that. I sometimes forget, we have members in other countries, that have different standards, rules, regulations. I only have one foot in the "IT" age.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

interesting stuff

Which Octane rating is best for my stock 74 Duster, 87, 89, or 93? Right now I run 89.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

I've always heard that the lowest octane that doesn't cause detonation is best and the most efficient.
Bob D

I just ran a tank of blened fuel through my '87 Dodge truck slant 6.
5 gallons of E85 (70-85% ethanol) + 15 gallons of E10 (regular gasoline in Minnesota).

Final mixture should have been 25 to 28% ethanol. Ran fine, got rid of the ping I had with regualr 87 octane stuff. Wonder what the octane rating was?

The regular 87 octane gasoline in MN contains 10% ethanol hence E10.

The E85 pump label states it contains minum 70% ethanol. Should be closer to 85%. Supposed to be 100+ octane.

if i remember correctly the booklet for my 73' scamp says to run a minimun of 91 octane......

Are you sure? I would think e-85, would be 15% ethenol and 85% gasoline. Since more ethenol is required, for a proper air fuel ratio, then gasoline, at 85% ethenol, major carb rejetting would be required. I don't know, I have never seen E-85.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225