Fuel used 47-53 Flathead
 

Hey guys,

New to the forum. Just wanted to pick your brains on what octane you are running in some of your late style flatheads. I recently purchased a 39 ford pickup and want to put in it whats right. Thanks

Mike

Re: Fuel used 47-53 Flathead
 

Regular is fine,stay away from E-85.

Re: Fuel used 47-53 Flathead
 

I like non-oxygenated, no alcohol. Don't know if you can get it in your state.

Re: Fuel used 47-53 Flathead
 

If you are in Florida go to a WaWa gas station and get non-ethanol gas its expensive but it won't eat up the rubber parts in the fuel system. Where as the ethanol gas will.

Re: Fuel used 47-53 Flathead
 

I siphoned the gas that was in my tank just recently after I had my carb rebuilt, and put in non-ethenol gas. It may cost a little more but I think I'll save money in the long run by having a better running car, and not having to replace lines etc.

Re: Fuel used 47-53 Flathead
 

"Non-Oxygenated" for sure if you can get it. Up here in the Brainerd-Lakes area, there are plenty of lakes and resorts. I find that gas stations (at least in Minnesota) in areas where there is boating tend to carry the no-alcohol stuff. If I'm guessing correctly from your user name, you are in Florida. I think the it's the same situation down there.

Re: Fuel used 47-53 Flathead
 

Here, in Iowa, we can still buy non alcohol "premium" gas for 50 cents more per gallon. It is 91 octane. You will get the gas left in the pump hose, but it doesn't seem to cause problems. We have run into unscrupulous dealers who put the cheaper fuel in the premium tanks to get more money, so buy from a good station.

Re: Fuel used 47-53 Flathead
 

Wow, I’ve never thought what a problem that is for you guys in the States. Here in Russia you can buy 80 octane gas. A couple years ago it was possible to buy 76 leaded. Now ecology gets attention but a lot of farm trucks still use 80 octane.

Re: Fuel used 47-53 Flathead
 

Why penalize yourself by limiting the old ford to non-alcohol gasoline.
A proper carb kit, a newer fuel pump & a good flex line will take away the alcohol worries with no location & price penalties.
You can buy 87 octane 10 percent gas anywhere.

Re: Fuel used 47-53 Flathead
 

Here in Oregon/Washington area there is no problem getting non-ethanol. It is about 50 cents more per gallon.

Re: Fuel used 47-53 Flathead
 

Same here in Minnesota.

Re: Fuel used 47-53 Flathead
 

Right on. Did that over 25 years ago.

Re: Fuel used 47-53 Flathead
 

Thank you all for all the great feedback!!! Appreciate it!

Mike

Re: Fuel used 47-53 Flathead
 

Fuel octane requirements are determined by the compression ratio (CR). Non-modified flatheads have a relatively low CR and can use the lowest octane fuel available (normally referred to as regular). Modified engines with a higher CR might require a higher octane fuel, but in most cases it is difficult to get the flathead CR high enough to require it.