pump gas?

[Omie01]

I am hoping to start my engine today! (351C). Can I use premium pump gas? I have hardened seats, CC heads, and forged flat top pistons. I think my CR should be around 10 to 10.5. I had my dizzy professionally curved, and am running a Pro Systems carb. I thought I saw a chart here once of which gas stations have the best fuel, but can't find it. PS: I do have access to 98 leaded, or 110 unleaded but they are stupid expensive and I was hoping to be able to run just premium pump gas this time around. Everything up here has 10% ethanol, and detergent additives, do these cause any problems? Any help would be greatly appreciated!!

 

[Mikes73]

You can run it on 91 octane but you may have to play with the ignition timing and carb jetting if you get spark knock. For example less ignition timing and larger jets in the carburetor. You will have to run it and see what it needs if anything. Good luck on the first fire up.

 

[Mister 4x4]

You should be fine. Mike's right, though: keep an ear out for any spark knocking and be prepared to make some adjustments - 10.5 CR is probably pushing the limits of "pump gas," from everything I've heard.

When you see the term "pump gas" with reference to performance cars (example: "2012 Shelby Super Snake makes 800hp on pump gas..."), they're referring to Premium Unleaded.

I have similar stuff in my engine (hardened valve seats, flat-tops, etc.), but my CR is only 9.5:1... and it runs just fine on Premium Unleaded.

 

[c9zx]

The ethanol eventually eats up any old style gaskets and seals as well as stratifying in the fuel tank, if allowed to sit for any significant length of time, causing corrosion in the tank. I'd run an appropriate additive to reduce the possible damage. I've never used an additive, we are fortunate to have 100% gasoline here, so I can't make a specific recommendation. The 4V CC heads should allow your 10:1 CR to work without detonation. Just get the advance curve right and limit the amount of vacuum advance to 10 degrees or less.

Let us know how the start up goes.

Chuck

 

[Jeff73Mach1]

I have trouble with running on pump gas at 11.5-1. Luckily there is a station with 110 available near my home so what I do is I put 3 gallons in then top off with 93 octane unleaded. If I know I won't get back there before I need gas, I'll up it to 4.5 gallons and top off with 93 when I get down to a half tank. An additive can also help. When I can get ethanol free fuel I do, but sometimes it isn't practical. If your timing and carb tuning is spot on, you should be able to run on 93 without anything else, but every set up will have its own particular needs.

 

[barnett468]

do a compression test . if it is over 180, try an autolite or motorcraft heat range 4 plug . stock was 5.

 

[Omie01]

Cool, thanks guys!!![/i]

 

[Carolina_Mountain_Mustangs]

Just a question. Back during WWII gas was bad and rationed also. Lots of people put water alcohol injectors in the carburetor to raise the octane of the bad gas. Is that something that could be done today? They had factory made units I have a book on one somewhere around here.

I did a quick search and here is one made today. http://www.alcoholinjectionsystems.com/

Could be a solution if compression is up there. I have an engine for my 65 vert that is built 12-1 so I will have to do something or run the expensive racing fuel.

David

 

[barnett468]

Just a question. Back during WWII gas was bad and rationed also. Lots of people put water alcohol injectors in the carburetor to raise the octane of the bad gas. Is that something that could be done today? They had factory made units I have a book on one somewhere around here.

I did a quick search and here is one made today. http://www.alcoholinjectionsystems.com/

Could be a solution if compression is up there. I have an engine for my 65 vert that is built 12-1 so I will have to do something or run the expensive racing fuel.

David

you can run alcohol injection but you have to keep filling it up snow products makes some.

with that much compression, i would also run an autolite or motorcraft 4 heat range plug.