Old engines vs. unleaded gasoline

I'm somewhat new here and don't know if this issue has been addressed before, but here goes: I currently have 3 small aluminum-block engines (2 - 3 Hp) from the late '50s and early '60s, which are in various stages of restoration. During those days leaded gasoline was the norm; the lead provided higher octane ratings (not really relevant to these engines), and also exhaust valve-seat lubrication (definitely relevant).
Now, of course, lead is extinct as far as fuel available at the pump. I plan to use these engines; what can I do about the fact that the exhaust valve-seats on these motors will wear abnormally fast with unleaded fuel (short of Steliting the valve seats, or some such process)? Are there any bottled fuel additives available that would work?

[Keith Smigle]

Mike~

The way I understand it, and I am sure some fellow stacker knows a whole lot more than this dumb dumb dummy, early gasoline was also unleaded. Lead was added I believe during WWII to meet the demand of the very high compression aviation engines. It was primarily an anti knock additive.

I know about as much about aluminum air cooled engines as I do a reactor on a submarine but I was thinking that surely there is some kind of exhaust valve seat pressed into the engine block or head (where ever the seat may be) Does any one out there know if this seat is capable of handling un-leaded gas?

~Keith in Delaware, oHIo

[Junkologist]

There has to be some kind of seat pressed into the block of an aluminum engine. I can't see aluminum holding up very well at all, even with tetraethyl lead in the gas. I mowed my grass with a 1940 Farmall A for almost 12 years using nothing but unleaded gas and did a valve grind on about the ten year mark. When I tore it apart, I found the intake valves to be in worse condition than the exhaust valves! I believe there is too big of a deal made out of the unleaded gas valve seat wear thing.

Mike

[George & Helen Myers]

Don't feel like going to the shop to check the Marvel Mystery Oil can but isn't there some thing about adding Marvel Mystery Oil to the unleaded gasoline. I know we were advised to put it in the tank of our 1965 Willys Jeep to prevent erosion and corrosion in the fuel bowl which is aluminum. Incidentally, the odometer on this vehicle has just now passed 20,000 miles. The body has some rust mainly in the tail gate. We have a new tailgate and a new rag top for it which we bought almost 10 years ago. It now has antique license on it. Also it has now been removed by the "high liability risk" insurance premiums. Liability insurances premiums on this vehicle has cost us almost 8 times more than the vehicle cost new. Now the antique insurance is very reasonable. It would have been cheaper to join our neighbors and feed a horse. Well, top speed is a just a little over 50mph......Helen

[Rick I]

The components that might suffer from no-lead are the exhaust valve seats. The valves themselves are already hardened, and the intake
valves run cooler by nature.

Hardened seats would be needed to withstand the
heat that causes valve seat recession. The exhaust valves and seats can get VERY hot, and when the valves close onto an old-style non-hardened seat, without lead, the valves can actually minutely weld themselves to the seat for a split second. When the valves open again, the welded metal is torn. Repeating this causes rapid exhaust valve seat recession. Having lead in the gas minutely coated the exhaust valve and seats, either cushioning the valve, "lubricating" is so the weld couldn't occur, or just dissipating heat better, I'm not sure which. Anyway, if you take away the protective lead coating, and run your engine in conditions where the exhaust valves/seats will get really hot (e.g. heavy acceleration/high rpms/heavy load), you are risking accelerated damage to your exhaust valve seats.

Lead was added merely as a means of inexpensively increasing octane.

The key here is "really hot"... if you aren't using your old engine under heavy acceleration/high rpms/heavy load (in a car, something like full throttle starts, trailer towing, or in a speedboat), I personally wouldn't worry about it; the amount of wear caused by the LACK of lead should be negligible.

-Rick I.

[Jim Tremble]

Briggs and Stratton has ALWAYS recomended no lead fuel. They must know something we don't.

Jim

[Don C. Wiley]

Charles F. Kettering, The inventor of the Delco-Light generator came up with Tetraethel Lead to raise the octane and I don't have the time to look up the date of that invention, but I'm saying in the late 40's or so.

Unless you load the engine real heavey I don't think you will have any valve problems.

Next to Edison, "My Man" Kettering has the second most pattents in the US, or did at one time.

"DELCO DON" Southern Illinois

[Ken Majeski]

Well... There is a lead substitute sold at most auto parts and fleet farm stores... But I remember reading a test report some years ago and the results were that engines that ran at about 1800 RPM or less there was very little valve seat wear anyway. They claimed that the lead substitute did very little good unless the dose was doubled. While not relevent to a 3600 RPM Briggs this is relevent to other engines. I believe other things will Get Your engines long before valve seat wear will. But it is amazing how long they will last with decent care...

[BobRR]

Wasnt lead added as a anti knock compound for higher compression engines?BobRR

[BWegher]

Big auto companies have tested this question. None found any reason to change valves due to removal of tetraethyl lead in gasoline. Your valves, valve seats, heads, plugs, mufflers will last longer using unleaded gas.

[RBackus]

Rick is right. Unless you're really running hard, it's doubtful you'll see a problem. Further, most of the seats in aluminum heads are hardened. I remember worrying about this when doing a valve job on a Norton Commando. The machinist said the seats were so hard he had to really work to cut them.

Richard Backus

[John Davidson]

I am quite sure ETHYL gasoline came about in the late 1920s when higher compression engines were used. I have 24 WADHAMS gasoline cards that Wadhams gasoline stations posted there prices. The oldest is dated Jan 1, 1934. These were for Milwaukee County (Wis). They list 3 grades of gas, Metro @ .17, Mobilgas @ .16 and Ethyl @ .20 a gallon. Of that price .04 was for state tax and .01 for federal tax The newest card is dated Nov 7, 1947 and the 3 grades were Metro @ .23, Mobilgas @.23 and Mobilgas Special @ .27. Wis state tax .04 and federal tax .015. Oh for the good old days except for the wages. How many remember the WADHAMS name? John D.

[Jim Tremble]

John

Those were high prices back then. Here in Vancouver, Wa. 1964-1970, there were some real bad gas wars. $0.17 per gallon was not uncommand. Fill the tank for a few bucks and you were set for the weekend. Then the gas crunch came in the early 70s. Still don't understand that one.

Jim

[CGBusch]

Originally Posted by rbackus

Further, most of the seats in aluminum heads are hardened.

I seem to remember this only being a problem in high compression cast iron heads without steel inserts. I'd think that all steel inserts won't be a problem.

[Norm S]

Our old engines don't need leaded gasoline unless you are running them hard for long periods. As to "needing" lead, I tore down my Farmall H last spring as one cylinder had a leaky exhaust valve and it generally needed overhauling. This tractor has been run on unleaded gas as long as it was out there - working hard sometimes plowing or whatever. In the last 15 years it hasnt run hard however. When I pulled the head off and took the valves out the exhaust seats (just ground into the cast iron head) were TERIBLE. I had hardened inserts put in at the shop so it wouldnt have this problem again. Lead was NECESSARY for these engines to maintain the valves!

Norm