At 05:55 PM 5/26/05 -0500, John Buntsma wrote:
"I saw that you are a proponent of Stellite valves and hardened seats. The mechanic who will be working on my engine and his machine shop both say the case for these modifications to guard against the dangers of unleaded fuel is overstated. They say after a couple of cans of lead additive, it will be fine. What is your view?"

I have lots of comments on the virtues of hard coated valves and hard seats in the Engine section. My overt enthusiasm for the Stellite exhaust valves comes from long term experience with lots of hard driving. I used to autocross every weekend for 7 months of the year. My trailer has beem hitched to the MGA for 100,000 miles of the 195,000 miles from 1986 to date, and I like to keep up with traffic in the fast lane. I used to need a touch up on exhaust valves at 40,000 miles, and replacement valves at 80,000 miles. With the hard seats and Stellite exhaust valves the engine runs for 100,000 miles (or more) without needing head work. The bronze guides are also still in serviceable condition at 100K.

The flip side is the initial expense to install these parts, and the expected benefit to cost ratio. It depends on how much you intend to drive the car, how hard you intend to work the engine, and how many miles you intend to accrue. The key ingredient for a no-lead head is hard seats. If the head is in for valve work anyway, I would definitely recommend installing hard seats, at least for the exhaust valves. If the head is worn enough to need new seats anyway, the difference in cost between hard or soft seats is negligable, and it would be almost criminal to instlall soft steel seats. I have a very good picture of that problem on my web site. Regular stainless steel valves hold up fairly well for normal daily cruising, and should easily last for 100,000 miles of normal driving, or perhaps 60,000 miles of heavy foot. If you are contemplating running the car another 100,000 miles, or doing a lot of hard driving, then the Stellite exhaust valves might be a good investment. If you intend to drive only a little and maybe never put another 50,000 miles on the engine, then forget the Stellite valves and save your money.

I personally have no use for lead additives. They are temporary in nature, needing to be used with perhaps every third tank of fuel. That makes them inconvenient (easy to forget) and expensive. If you intend to run the engine far enough to someday need another valve job (60K-100K miles), then the hard seats should be cheaper than long term use of fuel additives.

On the other hand, If you have an engine which is currently running well, particularly one which may not yet have hard valve seats, then you may feel there is some benefit to using a lead replacement additive. This might extend the life of the engine a few tens of thousands of miles, forestalling the inevitable valve job. If you can put it off long enough you might avoid it all together, in which case the fuel additive may be worth the investment. As mentioned before, the cost effectiveness depends on how many more miles you intend to put on the engine. The additives may extend the engine life a little, but not indefinitely.

Another fuel additive which may be beneficial in certain circumstances is a simple "gas line dryer", sometimes refered to as fuel line anti-freeze, one common brand being "HEET". The content of this product is largely alcohol, which absorbs water to hold it in suspension. If your car sits around a lot in a humid environment with half a tank of fuel, it may be subject to water condensation in the fuel tank. During very heavy rain storms it is not uncommon for gas stations to get some water in their underground tanks. If you suspect that you may have water in the fuel system, then a can of Heet may take care of the problem instantly.

There are a few different "flavors" of fuel dryer. One is largely isopropol alchohol. A solution of 70% isopropol alchohol and 30% water is commonly known a Rubbing Alcohol. In an emergency with nothing else available, rubbing alcohol could bail you out of a jam, but you may need to use about twice as much of it to be effective. Alcohol can absorbe up to 50% water in solution before it starts to separate. Rubbing alcohol starts with a considerable amount of water already in it, so there is only limited capacity to absorbe more water, which is why you would need to use more of it. The commercial fuel dryer will be closer to 100% alcohol, and also a little more expensive than rubbing alcohol. Mind you the retail price may be largely dependent on the cost of the container and the cost of distributiuon, and may have very little to do with the cost of the base material.

The second type of fuel dryer is largely ethanol alcohol, the same stuff that may compose 10% of the content of gasohol motor fuel (comonly known as E10). As many formulations of modern motor fuel may already be 10% ethanol (and sometimes more), the addition of a small percentage more alcohol to the fuel may be irrelevent (unless you just got a load of watered fuel from a flooded gas station). Ethanol alcohol is downright cheap these days, in fact cheaper by the gallon to produce than pump grade gasoliine. But don't believe for a second that a 12 ounce can of Heet should sell for $.25.

A third type of fuel dryer is largely methanol alcohol, which is not so often used in motor fuel in any large quantity because it is more expensive and also more corrosive to fuel system parts. It is not all that much more expensive, as it has (many years past) been used for seasonal cooling system antifreeze, before the common use of ethelene-glycol based "permenant" antifreeze. One distinct advantage of using methanol alcohol for a fuel line dryer is that it may be able to disolve ice. So if you already have a frozen (or partially frozen) fuel line, a couple of cans of this stuff sloshed around in the fuel tank may eventually get you un-frozen.

Fuel additives which claim to improve your fuel mileage will only do so by "correcting" some deficiency in your engine tuning. If you have a little ignition ping, and the additive makes the ping go away, chances are that either using a higher octane fuel or retarding the ignition timing a little would work as well (without the cost of the additive). If the engine problem might be dirty fuel injectors (hardly a problem with an MG), then anything which cleans the injectors would work as well. If you R&R the parts and clean them manually in solvent, then the fuel additive would not be of any benefit. Additionally, all modern motor fuel will have certain additives already included which help to keep things clean, so adding a little more cleaning solution may be totally irrelevent.

One common problem which MG engines may have is carbon buildup in the combustion chamber. This might be a result of long term running with overly rich fuel mixture, or more likely from oil running down worn valve guides. Such things were so common in past decades that the process of de-coking a cylinder head is often described in the factory workshop manual, and a service parts list might include a "cylinder head de-coking gasket kit". If your engine is getting long in the tooth (not so valuable), and you would rather not remove the cylinder head for theis process (expensive process), then you might try a product called "upper cylinder cleaner". This is a liquid largely composed of solvents, and in particular combustibe solvents, the most common one being mineral spirits (common paint thinner). Regular addition of this stuff to your fuel may (maybe) eventually disolve and burn away the carbon deposits.

But if the engine is old with worn valve guides, the carbon deposits may be accumulating faster that the fuel additive will remove it. To clear out significant accumulation of carbon deposits in short order you can virtually pour the upper cylinder cleaner down the carburetor. For this process you need to have the engine up to normal running temperature, then open the throttle to rev the engine in the 1500 to 3000 rpm range, and dribble the cleaner slowly into the carburetor. The cleaner will burn in the combustion chamber, and will burn a little hotter than the normal combustion process. The solvents will help to disolve the carbon deposits from the surface while they are being burned away and blown out the exhaust. The engine will be riunning very rich during this process, so you have to hold the throttle open enough to keep the engine speed up to prevent flooding and stalling. We hope you do not have sensitive neighbors, as you will be fogging the mosquitoes in the entire neighborhood in the preocess. But if all goes well a single pint of this stuff run through the engine in a few minutes time could do wonders for clearing out the carbon.

With the above noted exceptions, I have very few recommendations for fuel additives, and not much respect for hundreds of products lining the store shelves. Most of these products are composed fo "mouse oil", which is an old medicine man term for anything you can put in a bottle that costs a dime and sells for a dollar, whether it has any benefit or not (and mostly not). If certain fuel additives were actually useful and cost effective they would already be a resident part of your daily motor fuel formulation. So any off the shelf fuel additive which you may be thinking of using would be for a temporary fix or for a one time act of desparation. The only long term use additive I may see of any benefit would be a lead substitute product, but then used only to forestall the time of a valve job (slightly) before you get around to instlaling hardened steel vavle seats.

$.02,

Barney Gaylord