The Stovebolt Site Forums The Shop Area Engine Shop Lead addative fuel

Are any of you using a lead addative in your gas?
I have a 1951 halfton with a 1955 235 engine
Any benefits and if so whT are you using
Paul

Paul,

No lead additives in my trucks.

The major benefit if you have a low-compression stove bolt engine is the profit earned by the seller of the additive.

Yep- - - -P.T. Barnum is in the gas additive business these days! If you want to add a little Diesel fuel to the gas for valve guide lubrication and about a 5-point octane boost, 1 gallon of Diesel to 19 gallons of gas is the ratio we used to use on the round track cars. Most "octane boosters" are just very lightweight oil that increases the specific gravity of the fuel and slows down the burn rate a bit. "Lead substitutes" do nothing but suck money out of your pocket.
Jerry

The Gunk lead addtive and Marvel Mysterry oil is a good combo. Why not, cheap enough and does no harm. Stay away from any product which contains alcohol. I've written to Vavoline and Gunk they responded with good scientific evidence. Marvel had been around forever and a couple of ounces in your gas adds lubricty to ethanol infused gasoline. I guess it's all personal preference.

My gripe about lead free gas is valve guide and seat wear. I have a '68 Norton Ranger that I'm planning to put on the road soon and I have concerns about 10% ethanol added unleaded fuel eating the guides and seats, not to mentionwhatever it does to the seals, etc. in the carbs. The 'Burb has mid-80's 292 originally made for unleaded gas and the Sportster has had hardened valve seats installed so that's not a concern for them.

Does anybody know about using 1 tbsp or kerosene/gal as an octane booster and lubricant, like the post above using diesel?

#1 Diesel is nothing but kerosene. It's considerably more volatile than #2, but a tablespoon per gallon is a ridiculously small concentration. Numerous dyno tests we ran back in the mid-1990's put the necessary concentration at 5% by volume- - - -1 gallon of Diesel per 20 gallons of fuel mix.
Jerry

I can't provide any scientific support, but I have been adding lead additive to the tank of my 54 3100 with the original 235 engine and I can tell the difference. No change in performance, but I can tell you it quiets the engine down. I have engine knocking at start up and certain stages of acceleration running through the gears getting to cruising speed. The knocking is predominately more noticeable and more frequent without the additive. For 2-3 dollars a tank full, I will keep adding it. For those of you old enough to remember the gas commercials before unleaded gas, I can't remember which gas company but one of them would promote their anti-knock formula as a reason to buy their gasoline. Here is a link to the history of gasoline and they talk about lead as an anti-knock additive.

http://www.petroleumhistory.org/OilHistory/pages/knock.html

Dave you are right on...I use premium gas and additives and the 235 runs much better. Octane is a rating of several hundreds of chemical that make up gasoline. Octane is just a word to describe the mixture of said chemicals it's not a substance. A cup of good coffee is 5 bucks so a few bucks towards the health of the 235 is a no brainier. "The cheapskate will always pay more in the end". That's a fact.

Bob Hope was that gasoline commercial pitchman. "Knockout the knocks" he would say while wearing huge boxing gloves. Bob Hope will always be OK in my book.
re. which gas was it? Either Shell or Sunoco, danged if I recall which. LOL

re. OP, I used to use a cap full of MMO mixed in with a gal of gas in my old Wheel Horse Lawn and Garden tractors powered by K181 Kohlers until I tore one down and found a tar like black gunk on top of the piston and around the valve guides. Decided to stop and didn't see that gunk again. There was carbon buildup but no tar.

Your '51 was designed to run on 83 octane so running modern 87 is already providing an octane boost. I'm with Jerry on this one. Lead additive in a stock 235 that's operated within normal limits (not worked hard for extended periods & with stock valve springs) is unnecessary. If it makes you feel better, use it. Is it necessary? No. I've put many tens of thousands of miles on pre-unleaded engines using unleaded gas and have never had an issue.

Iso Octane does exist and it's the standard which helps determine a fuels anti-knock or Octane rating. The most accurate octane test is performed with an octane motor which is fed pure Iso Octane at a controlled ambient temp, and humidity, with a correction factor for atmospheric pressure. The Octane motor has a variable compression ratio and is run at a steady load during calibration and testing. During calibration while running on pure Iso Octane (which has an octane rating of 100) the compression ratio is adjusted to set the engine at the knock threshold by using knock detection sensors. Once calibrated the engine is fed the test fuel to be graded. If the engine detonates or knocks the compression ratio is reduced until knock can no longer be detected. Based on the amount of compression ratio change the fuel is given a number for it's anti-knock value or it's octane rating. In this example since the compression ratio had to be reduced to eliminate the knock the fuel has an octane rating of less than 100, if the compression ratio had to be increased to create a knocking condition then the fuel would be rated at greater than 100 octane. This is also known as the Motor Octane Rating. Based on decades of fuel testing chemists can do a good job of determining what a fuels octane rating will be based on the blend of the fuel (Research Octane) so Motor Octane Testing is rarely done anymore. I got a chance to sit through a Motor Octane test at a refinery years ago. Interesting enough they were performing fuel tests for a competitor which did not have an Octane Motor in their own lab. The motor's are large single cylinders with a threaded cylinder which can literally be screwed up and down to change the compression ratio while the engines running, pretty cool stuff. John

Combustion chamber shape has a lot to do with how efficiently fuel burns, and whether pre-ignition happens, which is the precursor to detonation. Stovebolt combustion chambers aren't particularly prone to preignition/detonation unless they get heavily carboned up and hot spots develop.
Jerry

You are correct..Octane is a measurement value of combination of specific gasoline base additives. However there is not a substance with the nomenclature of...Octane. Octane it is the added sum of the hydro-carbon based gasoline components. Therefore it is used as a measured rating.

So C8-H18 doesn't exist.

Here's a link:

http://alternativefuels.about.com/od/glossary/g/octanerating.htm

Iso-Octane is the fuel with the "100" rating

Heptane knocks in everything- - - -even a Biggs & Stratton lawn mower.

The percentage of Iso-octane that produces a specific knock point is equivalent to the octane rating- - - -the rest of the blend is Heptane. It's been that way as long as I can remember, back into at least the early 1950's.
Jerry

Based on what I have seen and used, (104 Octane Booster) all I got from it was red fuel and discolored valves. If the engine has a compression ration that will run on 87 octane, adding more will not help. Now if the said engine has hot spots on the head, odd ball pistons, or timing out of whack, then the higher octane could help. My stock 250 has 8.0 to 1 compression, running 87 octane or 93 octane (no corn added), the mileage and performance is always the same. I have run plenty of test for fuel mileage, so I stand by this one. Even my race car didn't show any difference when going up on octane, the engine was happy with what it had. My '85 Dodge 318 used to ping like made on 87 octane, I sold it with 200,000 miles on so I can't say how long it kept going and pinging.

Again, this is my observations, if you get good results, that great, it keeps the old trucks out on the road where they belong!

Joe

octane RATING is the measurement of the effectiveness of the various combinations of fuel that are out there. Whereas OCTANE is absolutely a substance that is used to set the guidelines for determining the RATING. The gas doesn't necessarily have to have octane in it, just have an equivalent resistance to knocking, detonation or what have you. So yes, octane does actually exist.

I think we've beat this dead horse long enough. The discussion has become circular. If the regular forum mods think this subject is worthy of further discussion they can unlock it.