Fuel used for High Performance 440

[Davison]

I have not driven my 1972 Road Runner in 10 years. I have drained and cleaned the fuel tank and lines and will start on the carb. After I get everything back I want to use the best fuel possible. I know in 1972 it was just the start of the low-lead and un-leaded fuel. The service manual says to use leaded fuel every fourth tank full. Well, that is not possible. So what do you do to prevent the valve recession on these high performance engines? The 440, Hemi, 383 etc. I guess I could just use normal unleaded and drive slowly, but that won't happen. Thanks!

 

[moparnation74]

If the motor is stock...hence stock compression 93 octane is fine....

 

[PP1RT]

Run pump premium. The valves aren't going to wear out from the lack of lead for many many miles. You may find your valve stem seals have dried out from sitting. Somewhere in the future when you do a valve job have them cut in hardened seats if you want to remain stock.

 

[lewtot184]

there's a lot of variables that lead to valve seat recession.

 

[threewood]

I have not driven my 1972 Road Runner in 10 years. I have drained and cleaned the fuel tank and lines and will start on the carb. After I get everything back I want to use the best fuel possible. I know in 1972 it was just the start of the low-lead and un-leaded fuel. The service manual says to use leaded fuel every fourth tank full. Well, that is not possible. So what do you do to prevent the valve recession on these high performance engines? The 440, Hemi, 383 etc. I guess I could just use normal unleaded and drive slowly, but that won't happen. Thanks!

You can cut it with race gas, i.e. Sunoco 110 which is leaded.

 

[the mississippi madman]

They have octane boosters that have lead or lead substitute additives in it

 

[Davison]

So, just run 93 and not worry, or add a lead additive and there are plenty of them. I don't know of any Sunoco station reasonably near here that sell racing fuel. Nice to have one though.

 

[mopar 3 B]

1972 - 8.2 comp ratio hardly requires premium gas.
If you have a local source of un-alchol premium other wise known a boat fuel use it. Save the stress of worrying about those rubber parts and fuel perculation.

 

[Montclaire]

Try to find ethanol free fuel and add a can of lead additive. If all you can find is 87 in ethanol-free, you are probably better off using that with the lead additive plus an octane booster (or combo of the two if avail locally) as opposed to a 93 with ethanol.

 

[Bruzilla]

Here's a good site for finding Ethanol-free gas. https://www.pure-gas.org/index.jsp?stateprov=MI

More than the gas, I would be worried about the gas tank. If the car hasn't been run in ten years, cleaning out the tank isn't enough. I learned this the hard way when I cleaned all the crud out of mine and then started having fuel flow issues months afterwards as rust started clogging everything up. In addition to the tank being rusted, the fuel sender has corroded away to almost nothing.

I would suggest dropping the tank, pulling the sender, and then scoping out the inside of the tank using one of those USB bore scope cameras. If there's any corrosion on there, get a new tank.

 

[Silver Hemi]

If the motor is stock...hence stock compression 93 octane is fine....

69 RT 426 Hemi, lightly built engine supposedly true 11 1/2 to one compression ratio. with a moderate cam dual Edelbrock four barrels. I have a major hesitation when throttling up that seems to be even worse when I use VP 110 leaded fuel hesitation disappears when I use 93 octane unleaded from Costco. Has anyone ever heard of such a thing?

 

[Master Gunner]

First step would be to confirm your compression, next would be to check your cam numbers. If the compression is what you say, the first thing that comes to mind from what you describe is ignition. What you have to understand is what octane is, which is resistance to ignite. This is how we are able to build high compression engines without detonation. With higher compression comes the need for a hotter spark and or more timing to light the fire, which is a possible (not the only) answer to why you run better on lower octane fuel.

This probably should be it's own thread to get more/better answers

Mark

 

[mopar 3 B]

69 RT 426 Hemi, lightly built engine supposedly true 11 1/2 to one compression ratio. with a moderate cam dual Edelbrock four barrels. I have a major hesitation when throttling up that seems to be even worse when I use VP 110 leaded fuel hesitation disappears when I use 93 octane unleaded from Costco. Has anyone ever heard of such a thing?

Is this a non alcohol fuel to alcohol comparison? I can't even buy leaded fuel.

 

[Black_Sheep]

Not 100% sure, but I believe that hardened valve seats were used in 1972.

 

[Skytrooper]

I use non-ethanol 90 octane. No issues.

 

[Bo Hardin]

I go to the local airport and fill up with aviation fuel, no ethanol and high octane for my 72 440 HP

 

[33 IMP]

I add a couple gallons of 100LL avgas too....



but I figure the o.p. has decided what to use in the seven years since this was first posted.

 

[tak419]

I go to the local airport and fill up with aviation fuel, no ethanol and high octane for my 72 440 HP

What airport is letting you fill a car at the pump cause that's illegal as heck. I'm not gonna start an argument but I know many people who fly, also know a few people that work at BP refinery, AV gas is not the same octane rating as car gas. It's designed to burn at high altitudes, so it does Not produce the same octane at normal altitudes cars operate at. I think pilots know way more about gas octane ratings than a guy at the local race track listening to old timers talk about filling their car at the airport lol

 

[Photon440]

What airport is letting you fill a car at the pump cause that's illegal as heck. I'm not gonna start an argument but I know many people who fly, also know a few people that work at BP refinery, AV gas is not the same octane rating as car gas. It's designed to burn at high altitudes, so it does Not produce the same octane at normal altitudes cars operate at. I think pilots know way more about gas octane ratings than a guy at the local race track listening to old timers talk about filling their car at the airport lol

I think enough people have successfully burned avgas in high performance cars to know that it works. Remember, although planes fly high up, they are usually at their highest power setting during the take-off run on the ground.

Anyway, lead in avgas is going to be on its way out as well.

 

[fullmetaljacket]

So, just run 93 and not worry, or add a lead additive and there are plenty of them. I don't know of any Sunoco station reasonably near here that sell racing fuel. Nice to have one though.

There is racing fuel at the pumps ion Orchard Lake road and others in Livonia county. You have to bring a labeled and correctly colored 5 gallon jug. Check the internet for places close to you.