Fuel octane question


http://209.208.111.198/Topic105382.aspx 		Print Topic | Close Window

By 57f600boy - 11 Years Ago
Hello, i've got a 1957 f600 with the stock 272 yblock fresh rebuild i am the 3rd owner and all other owners were family so, my grandfather said he had the engine rebuilt less than 100 miles ago (in 2013) i am in the process of restoration and about ready to begin driving it soon and i know enough about the rest of the truck but im not so good with gassers mostly diesel is what i dealwith around the farm here but to cut to the chase what would the best octane be to run in this stock engine? Premium is what i was running it since the rebuild but is premium best for this engine?

Thanks
By gekko13 - 11 Years Ago

Not nearly enough information to give you an opinion.   What are the engine specifications?  Comp. ratio?  Intended use? 

By charliemccraney - 11 Years Ago
Regular should be fine for a stock rebuild and very likely fine for even typical modifications.  The possible exception is if it had domed pistons installed so that it actually has some compression.
By 2721955meteor - 11 Years Ago
agree with charley,my 292 with eczg heads i run reg,87 just have to keep advance reasonable.
By Ted - 11 Years Ago

While the static compression ratio on the 272 is low enough that you can run 87 octane fuel without issue, the amount of ethanol in the premium grade is less (typically 5% or zero) and the shelf life of premium is also much longer. If the truck is not going to be used a lot, then having premium fuel in the tank helps in the long run.  Your carburetor, fuel lines, and tank will also like any reduction in ethanol you can give them.

It pays to check the ethanol content in the fuel you are buying as I’ve found up to 30% ethanol in pump gasoline that’s advertised as being no greater than 10%.  That particular 30% case was suspected to be gasoline that had broken down by both age and moisture absorption within the dealers tank.  By the same token, I check the premium gasoline regularly and as a general rule find it being no greater than 5% versus the 87 and 89 octane fuels being right at 10%.