Lead Additive?

[jeff70]

Maybe someone can help me with this one, if a car, 1971 has 135k orignal miles the motor has never been opened up, should i use a lead additive? I just bought this car and the lady is 80 yrs old and was adding it everytime she filled up the tank. Will it hurt to not use it? Thanks Jeff

[Rob Peters]

I use a lead additive in my car Monte and my Model A Ford. Both of these cars were built when lead was added to the gas. The lead in the gasoline helped with the valves by creating a slight buildup of lead on the valve seats which not only quieted the valve tap noise you may get but also provide a more positive seat of the valves in the valve seat (sort of like an o-ring seal) which provided a better seal of the valve into the seat. This better sealing of the valve into the seat allows for better compression.

That is the simplest way I can explain it, I am sure someone else can do a better job.

I wouldn't say I add it every fill up but I do use it. Modern day heads and even if you get your heads redone they can build them for the unleaded gas.

Rob

[jeff70]

Thanks Rob, i do know that these heads have never been touched and because they have never been rebuilt is it a must to run the additive. I dont want to cause any damage to the motor in the case i dont run it. Thanks Jeff

[montefrazer]

This is quoted from the 1971 Monte Carlo owners manual. "All 1971 General Motors cars including your Monte Carlo are designed to operate on unleaded or low-lead (0 to .5 grams per gallon) gasolines. Use of unleaded or low-lead gasoline will keep your engine running efficiently and play an important part in reducing exhaust emissions of hydrocarbons and particulates." You can use a lead additive but it's not necessary. With that amount of miles and the engine being untouched, I would recomend replacing the timing chain and gears. This is a well known problem area for these motors.

[Mo's70MCs]

Lead served a dual purpose as a gas additive: -It was a cheap way to increase octane rating -It coated nicely the inside of the cylinders, reducing wear.

 

Of course, Tetra-ethyl lead is toxic, to the environment in general, and to people, including you and me.

 

E.P.A. Fact sheet:

 

 

Leaded Gas Phaseout

 

Air Quality Fact Sheet

 

June, 1995

 

 

Leaded gasoline will no longer be available in the United States after December 31, 1995.

 

The Clean Air Act Amendments of 1990 mandate the elimination of lead from all U.S. motor fuel by January 1, 1996. This

represents the final step in a gradual reduction of lead in gasoline since the early 1970s. "Regular" gasoline typically

contained approximately 4.0 grams of lead per gallon; average lead content was reduced to 0.5 gram/gallon in 1985, and

still further to 0.1 gram/gallon in 1986.

 

"Unleaded gasoline" is allowed to contain no more than 5/100ths of a gram of lead per gallon.

 

Why remove lead from gasoline?

 

Lead is extremely toxic. Studies show that exposure to high concentrations of lead, particularly in young children, can result

in damage to the central nervous system, and may be associated with high blood pressure in adults. Human exposure to lead

typically occurs via inhalation of air and ingestion of lead in food, soil, water or dust.

 

Airborne lead concentrations throughout the country have decreased 89 percent since 1984, directly due to the phaseout of

leaded gasoline, as well as to the majority of cars equipped with pollution control devices that require using unleaded fuel.

 

How will unleaded gasoline affect my older car's performance?

 

A basic rule of thumb for refueling a pre-1971 vehicle is to use unleaded gasoline with the same octane rating as the

previously-used leaded gas. Under normal driving conditions, the use of unleaded fuel should not cause any problems with

the vehicle's performance.

 

Pre-1971 engines were equipped with "soft" valve seats and leaded gasoline acted as a lubricant to prevent excessive wear

of the valve seats. Using these engines with unleaded fuel in high-speed/high-load situations could result in some valve seat

wear. (Boats, some farm equipment, and tow vehicles may be included in this category.) Substitute lubricant additives are

available at auto supply stores to help this situation. In addition, valve seats are usually replaced with at the time an older

engine is rebuilt. If you are concerned about your particular application, check with your engine manufacturer.

 

Does this mean my engine will wear out sooner without the protection of lead?

 

No. In fact, unleaded fuel can help extend maintenance intervals. In the past, lead deposits on spark plugs were the main

reason to change them so often. Today's cars are built with pollution control equipment that is specifically designed to run on

unleaded gas.

 

So I guess they had us believing that we've been filling our cars with unleaded fuel.

Rod

 

[jeff70]

Thanks for the help i just bought this car its not a Monte, its a 71 Cutlass convertible that i just bought from the orignal owner with all the records from day one. I also have a Monte that has now been made into a convertible, and as far as i know the 350 in my Monte has never been gone through and i just put unleaded in it. I just had some questions because i heard that the cars from the 60's and 70's were built to run leaded gas and to run unleaded you would need to rebuild the heads to except unleaded gas. Thanks Jeff

[AndyBill402]

As already mentioned, tetraethyl lead was added to gasoline as an inexpensive, but very effective way to increase octane. It also coated the inside of the combustion chamber. This added a cushioning effect to the valves when they closed. It's especially helpful to the exhaust valve. Up until 1971, valve seats were just milled into the cast iron head. Without lead, the pounding of the hot exhaust valve against the head would quickly erode the valve seat. Beginning in 1971, the valve seat was still milled into the head, but it was "induction" hardened. Beginning in 1972, separate hardened valve seats were pressed into the heads.

 

We all know lead is toxic, but has anyone (and I mean anyone) read any (and I mean any) studies showing any (and I mean any) detrimental effects to humans from tetraethyl lead? Lead was first added to gasoline over 80 years ago. If the effects of tetraethyl lead were as toxic as claimed, every adult from the WWII era and the post-war Baby Boomers should either be dead from lead poisioning or severly brain damaged. I'm 56. I grew up in a lead environment. In 1974 I was tested for lead toxicity because I was on a shooting team, and they required it. I had no detectable lead in my body although I breathed lead fumes all my life.

 

On advice from an acquaitance of mine who is an engineer in the automotive industry, I add lead substitute to every car I own. It's not lead, but rather an effective and legal substitute. You cand find several brands on the shelves at your parts store. I recommend using them.

[jeff70]

Thanks again for the info, i've decided to just keep running the additive only because the car runs excellent and why change atleast maybe till i decide to rebuild it.

 

Thanks Jeff