Can someone suggest the proper fuel octane# for my new (for me) '72 280SE 4.5? The compression ratio for this engine is specified as 8:1. Thanks to all who can provide help!

That motor should run fine on regular,BUT. There never was a fuel system used that was more dependant on ignition timing for good power and fuel mileage. Even on regular they can be timed 5 degrees ahead of spec. If they will run ten degrees ahead with premium, you will make up the cost in extra mileage (they can get 18 if set this way and leaned out properly; instead of the 12-15 its probably getting) and the performance will be a great side benefit.

I have been running regular unleaded 89 octane for the most part, with no pinging and good power. Occasionally I fill the tank with mid-grade 92 just to give a little boost. I consistantly pull 12 mpg in town, and haven't had the gumption to make a long highway run to see what the mileage would be.



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Mike Tangas
73 280 SEL 4.5