Leaded fuel replacement options

66 Fury III Convertible

66 Fury III Convertible

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I had a 1966 Fury III convertible in High School [circa 1983] and Leaded fuel was readily available. Sold car due to family responsibilities, BUT... Now I purchased a very similar car. It is time to fuel it up for the first time and I know that Leaded fuel lubricates the valve train and need the best modern equivalent.

It is a 1966 Ply Fury III conv. with 383 2bbl. with 107k on the clock. Any help and or advice would be appreciated, do not want to cause ignorant damage.
Thanks in advance.
 
You will get different opinions on what you should do. I would run 91 - 93 octane unleaded and through in a botlle of lead additive every few months if you drive the car a lot. Doing this has worked well for me for many years.
 
I have high compression in my 440, so I have used leaded VP racing fuel. I add a few gallons when I fill it up and it works great. I don't drive that much, so it isn't breaking the bank. There are several lead substitutes on the market you could use. If the octane is ok, then what FURYGT said makes sense.
 
There used to be a fuel additive called "Real Lead". Reading the back of the can, the actual amount of tetraethyllead in it was minimal and might take two cans to get the unleaded fuel to even "low-lead" standards, in a 20 gallon tank.

There are other compounds which can be added to unleaded fuel which decrease valve seat wear.

Back in about 1974, I found an article in a Chilton magazine which detailed a Chrysler test on a '72 Town & Country wagon with the HD trailer package and 440, pulling a "max weight" travel trailer around the proving grounds at highway speeds and pure unleaded fuel (with non-hardened valve seats, which were standard until the hardening process was released a year or so later). Anid those proving ground circuits can put more load on the engine than normal Interstate cruising.

Under those constant, "heavy use" conditions, the majority of the valve seats were leaking, eroded, or completely failed, by the 12K mile mark. Under a lighter-duty driving cycle, with cooler exhaust valves and less consistent load, I suspect they would have gone a good deal longer.

I've had a set of 906s on my '67 Newport 4bbl for well over 50K miles with no issues. Prior to installation, they did get a full valve job, some new Chrysler 440 6bbl valves, and bronze helicoil valve guides. No issues with normal super unleaded fuel.

At one time, I was using some Stewart-Warner Lead Replacement additive, which I believe is sodium-based. That sodium soft-glued the accel pump anti-pull-over check valve closed, making the car extremely hard to start and drive (with no accel pump). When I freed it up, that was the last time I used that stuff!

Be more concerned about using a gasoline that will prevent pinging on acceleration and enjoy the car. Saving money for a timing chain replacement and rubber fuel line replacement (tank to carb) . . . as preventative maintenance measures, IF they have not already been done. When and if it might need a valve job, you can THEN worry about doing "hard seats".

Enjoy!
CBODY67
 
If you do a search, you will find some info on the use of an ounce or two of TCW3 marine oil (a 1:500 ratio) in your tank to act as an upper cylinder lubricant.
 
66 Fury III Convertible said:
I had a 1966 Fury III convertible in High School [circa 1983] and Leaded fuel was readily available. Sold car due to family responsibilities, BUT... Now I purchased a very similar car. It is time to fuel it up for the first time and I know that Leaded fuel lubricates the valve train and need the best modern equivalent.

It is a 1966 Ply Fury III conv. with 383 2bbl. with 107k on the clock. Any help and or advice would be appreciated, do not want to cause ignorant damage.
Thanks in advance.
Click to expand...
IMHO....

The Mopar valve seats, while not specifically hardened, are still harder/more durable than other brands. As such, running unleaded doesn't destroy them. Running it in a car that might get a few thousand miles isn't going to hurt much, if at all. To put things in perspective, Amoco gas was always lead free, even back when lead was available. People swore by it and ran nothing else.

Myself, I refuse to use any additive that would "replace" leaded fuel. Anything that actually does replace it would be too toxic to handle with bare hands and no PPE. The rest is snake oil.
 
Big_John said:
IMHO....

The Mopar valve seats, while not specifically hardened, are still harder/more durable than other brands. As such, running unleaded doesn't destroy them. Running it in a car that might get a few thousand miles isn't going to hurt much, if at all. To put things in perspective, Amoco gas was always lead free, even back when lead was available. People swore by it and ran nothing else.

Myself, I refuse to use any additive that would "replace" leaded fuel. Anything that actually does replace it would be too toxic to handle with bare hands and no PPE. The rest is snake oil.
Click to expand...
Out of curiosity, have you used othe engine cleaners ( additives ) ?
Once my 67 Newport is all back together I was thinking of adding some Sea Foam for it's maiden voyage once safetied, any opinion on other additives out there?
 
polaratherapy said:
Out of curiosity, have you used othe engine cleaners ( additives ) ?
Once my 67 Newport is all back together I was thinking of adding some Sea Foam for it's maiden voyage once safetied, any opinion on other additives out there?
Click to expand...
Myself, I don't use anything. Seafoam does have some people that believe in it's use, but I'm of the opinion that there's not much in one of those little cams that does much good.
 
Way back when the cars were new and used, there were no really beneficial additives other than some snake oil. Berrymans B-12 (the Berrymans DID work) and was what the local mechanics used exclusively, but the absolute BEST way to de-carbon an engine was to fill it up with good fuel and DRIVE it. I thought our '66 Newport 2bbl ran good, but each time I did a 400+ miles round trip home and back to school each month, it did run just a bit better after each trip. BTAIM

Back then, too, when Gulf Oil was still intact, they had a fuel additive named "Tri-Ad". It was a great fuel system/carb innards cleaner. Worked great and quick, but it disappeared along about the time that unleaded fuel appeared on the scene.

Some would get a Coke bottle, fill it with water and atf, 50-50, and drizzle it into the carb, keeping the engine running during all of that. Sounded like a rod was going to come of the side, but didn't. On seriously-carboned engines, it would make a difference. Then they'd add a bottle of B-12 to the gas and maybe use a spray can of B-12 to spray down the carb and the venturis.

Berryman's B-12 was around before the mid-1960s and I know it works. Basically a type of lacquer thinner, I suspect, but only have heard of Seafoam in the past few years. FWIW

Modern fuels have MUCH more detergents and cleanliness additives, to meet various OEM specs, that is isn't funny. So, comparatively, nothing should be needed in normal use. Look for "Tier 1" fuel labels on the gas pumps.

As to cleanliness/clean-up additives, there are some videos on such in the "Chris Fix" YouTube channel. He uses a borescope to investigate the tops of the piston tops, before and after, for several popular fuel treatments.

Many times, people will perceive they need to clean things up. They'll buy a popular fuel additive, put it in, and then nothing changes. Which means the additive was not really needed, not that it did not work, it seems to me. I've used one of the name brand fuel cleaners and could not tell any difference after that tank of fuel was used. Your experiences might vary. Watch the Chris Fix YouTube videos, too.

Using some ethanol treatment might be considered, but do NOT let the car sit and the float bowl fuel evaporate (as one carb shop owner mentioned in another forum). Some Marvel Mystery Oil will work in gasoline, too, at recommended dosages. Just not for valve seat issues.

Just some thoughts and observations,
CBODY67
 
Last edited:
Big_John said:
Myself, I don't use anything. Seafoam does have some people that believe in it's use, but I'm of the opinion that there's not much in one of those little cams that does much good.
Click to expand...
Still lots of snake oil out there? I decided to give it a try by word of mouth, not advertisement, a buddy suggested it as he uses it in a 70 Fury and a few other classics he has.

Thanks
 
CBODY67 said:
Way back when the cars were new and used, there were no really beneficial additives other than some snake oil. Berrymans B-12 (the Berrymans DID work) and was what the local mechanics used exclusively, but the absolute BEST way to de-carbon an engine was to fill it up with good fuel and DRIVE it. I thought our '66 Newport 2bbl ran good, but each time I did a 400+ miles round trip home and back to school each month, it did run just a bit better after each trip. BTAIM

Back then, too, when Gulf Oil was still intact, they had a fuel additive named "Tri-Ad". It was a great fuel system/carb innards cleaner. Worked great and quick, but it disappeared along about the time that unleaded fuel appeared on the scene.

Some would get a Coke bottle, fill it with water and atf, 50-50, and drizzle it into the carb, keeping the engine running during all of that. Sounded like a rod was going to come of the side, but didn't. On seriously-carboned engines, it would make a difference. Then they'd add a bottle of B-12 to the gas and maybe use a spray can of B-12 to spray down the carb and the venturis.

Berryman's B-12 was around before the mid-1960s and I know it works. Basically a type of lacquer thinner, I suspect, but only have heard of Seafoam in the past few years. FWIW

Modern fuels have MUCH more detergents and cleanliness additives, to meet various OEM specs, that is isn't funny. So, comparatively, nothing should be needed in normal use. Look for "Tier 1" fuel labels on the gas pumps.

As to cleanliness/clean-up additives, there are some videos on such in the "Chris Fix" YouTube channel. He uses a borescope to investigate the tops of the piston tops, before and after, for several popular fuel treatments.

Many times, people will perceive they need to clean things up. They'll buy a popular fuel additive, put it in, and then nothing changes. Which means the additive was not really needed, not that it did not work, it seems to me. I've used one of the name brand fuel cleaners and could not tell any difference after that tank of fuel was used. Your experiences might vary. Watch the Chris Fix YouTube videos, too.

Using some ethanol treatment might be considered, but do NOT let the car sit and the float bowl fuel evaporate (as one carb shop owner mentioned in another forum). Some Marvel Mystery Oil will work in gasoline, too, at recommended dosages. Just not for valve seat issues.

Just some thoughts and observations,
CBODY67
Click to expand...
Back in the day, people came up with all kinds of concoctions and methods of trying to circomvent bringing their car to the shop.
I will check Chris Fix, thanks.
 
I'm using ethanol-free 91 octane from Maverik. I put a bottle of Motor Medic Lead Substitute or similar every other fill-up. Haven't put more than about 600 miles on the car since I bought it, so nothing to report yet, but just thinking proactively.
 
I use the marine 2 cycle(tc-w3) without fail as non ethanol fuel isn’t easy to get in my neighborhood. Is it snake oil? I don’t think so from the complete lack of this gelatinous build up in the bowls of the carbs that I used to have to clean out regularly before I started using it. That’s mainly for dealing with the ill effects of the ethanol though. Replacing the lead doesn’t concern me even before hardened seats.
 
detmatt said:
I use the marine 2 cycle(tc-w3) without fail as non ethanol fuel isn’t easy to get in my neighborhood. Is it snake oil? I don’t think so from the complete lack of this gelatinous build up in the bowls of the carbs that I used to have to clean out regularly before I started using it. That’s mainly for dealing with the ill effects of the ethanol though. Replacing the lead doesn’t concern me even before hardened seats.
Click to expand...
I wouldn't say that was "snake oil" as it's not sold with some wild promises. It's 2 cycle oil...

I've been reading a little about the gas stabilizers they sell for storage. It's been said that the stabilizers are just a kerosene based liquid that forms a film on the top of gas to effectively seal it from absorbing water. That makes me wonder if the 2 cycle oil is doing the same thing?

Myself, living in the Finger Lakes, I have my choice of gas stations with ethanol free oil as they cater to the boating crowd. I can name 4 stations within a 5 mile radius without thinking too hard.... But that goes away when I travel. So, I'm wondering about using it while I'm out of town and have no choice.
 
Big_John said:
I wouldn't say that was "snake oil" as it's not sold with some wild promises. It's 2 cycle oil...

I've been reading a little about the gas stabilizers they sell for storage. It's been said that the stabilizers are just a kerosene based liquid that forms a film on the top of gas to effectively seal it from absorbing water. That makes me wonder if the 2 cycle oil is doing the same thing?

Myself, living in the Finger Lakes, I have my choice of gas stations with ethanol free oil as they cater to the boating crowd. I can name 4 stations within a 5 mile radius without thinking too hard.... But that goes away when I travel. So, I'm wondering about using it while I'm out of town and have no choice.
Click to expand...
Do you think the 2 cycle oil has to be marine or lets say 2 cycle I use for my chain saws, snowmobile or leaf blower and so on.
 
polaratherapy said:
Do you think the 2 cycle oil has to be marine or lets say 2 cycle I use for my chain saws, snowmobile or leaf blower and so on.
Click to expand...
I don't know what the difference would be... So I googled it and came up with this: Marine 2 Stroke Oil VS 2 Stroke Oil: (Explained)

It looks to me like the main difference is the marine oil is an ashless oil. From reading bits from other sources, I believe that means no zinc in the oil and it translates to less deposits on valves and combustion chambers. It also looks like instead of using regular 2 cycle oil to replace marine 2 cycle oil, it wouldn't be a bad idea to use the marine oil in your chain saw etc. That's a bit of speculation on my part.
 
Running lead sub is not necessary. I do use premium though, in the Newport and the Gremlin.
 
Been driving my old cars on unleaded, before the addition of ethanol, and unleaded with the addition of ethanol, can't even imagine the amount of miles driven on unleaded and have never experienced any valve-valve seat problems.

Those who say they have had previous valve seat wear prior to the use of unleaded fuel.
 
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