Reg versus Premium Fuel experiament in 09 PT Cruiser

What was found was that if you ran leaded fuel for a few thousand miles it built up a coating that could provide protection for a long time after that even if you burned unleaded. But if you took a new 66 engine that had never been run and started it off on unleaded it would burn the valves relatively quickly. That's why when leaded gas was phased out there wasn't the problem people thought there would be - all the already in service cars had been run on leaded for a long time and the new ones had hardened valve seats.

I wasn't aware of the faster electrode erosion with lead, but I do know that quite often spark plug life was limited because of the lead being vapor deposited onto the insulator that bridges the electrodes such that eventually the surface of the insulator became conductive and would short out the voltage before ionization/spark could occur. That's what I saw more than anything forcing spark plug replacement when I was a much younger DIY'er.

I bet most people aren't aware that today, lead is one of the powdered ingredients in many brushes in the d.c. motors and alternators on our cars. I was amazed to learn that when I worked as an engineer/engineering manager in a brush manufacturing company supplying

60% of the brushes to the U.S. auto industry.

Think about it - lead in the brushes - brushes that wear and create dust that gets blown about into the air. Who'd a thunk that they would allow that - but it's a fact and you never hear anything about it. Whyizthat?

I thought the opposite was being claimed. Did you mis-type there?

I never said you implied that. I said that the lack of lead should in fact cause unusual wear to the valve seats, so I am curious where the added engine lifetime came from here. Cite, please?

--scott

Again this is an issue of efficient combustion which tended to be hit or miss back in the 60's. So there was a whole science to how your engine was running (or how it could be improved) depending on how the spark plugs deteriorated.

-jim

That's BS. I suppose next your claim that when you rebuild an old engine that protective lead coating penetrates even deeper than the metal removal from grinding the valves. The protection of a lead coating is Voodoo.

More BS. It is not as if valve seat recession didn't occur when engines were using leaded fuel. In fact back then it happened frequently. One of the reasons was the breaker point ignition always meant that the engine spent a considerable amount of its life with late timing due to breaker points wearing down. Subject a modern engine to the same late timing and it will burn valves also. And detonation is hard on the intake valves so advancing the timing in anticipation of the expected wear would also cause problems. The simple fact is that in order to make a 60's engine last as long as a modern engine you need to do a tune-up with the same frequency as you change oil. Where is the evidence for these engines that burn or recess valves without leaded fuel? If you install a properly working electronic ignition in an old style engine you are probably doing more to protect the valves from burning than hardened valve seats will.

This whole business of lead protecting valves was a made up lie in the first place. It is a fairy tale designed to scare the public into continuing to poison itself. What protects valves is efficient combustion. The octane increase from lead made efficient combustion possible. Raising octane by other means can accomplish the same thing. There is no protective coating from lead. In fact the byproducts of burning lead have been shown to accelerate engine wear.

-jim

I don't know what you intended to write here, but I can tell you that the cam would likely fail in very short time due to the reduction of ZDDP additives in todays oils.

I ran down one lobe on a 351C in Italy (I'm from Sweden) in 2004 while using Mobil 1 5W-50 oil, and a lot of 351C owners have had flat tappet cams fail in very short time, some even during cam break in, using modern oils.

I'm now running a hydraulic roller cam and roller rockers, and it has at least survived a trip to France.

Thomas

Possibly. A lot of people have run a *lot* of miles without trouble. Unfortunately I wasn't one of them- lost a valve and had to put in hardened seats. Still made it to over 200k miles on that engine though.

That's probably true. Plus hardened seats were snuck into production a number of years before the actual requirement. Chrysler started putting induction hardened seats in some engines around 1970, and lead wasn't finally eliminated until the 80s.

jim wrote: The simple fact is that in order to make a 60's engine

OK, let's separate the problem here. Theres the hard mechanical parts of an old engine (rings, bearings, pistons) and then there's accessories (carburetion, ignition). The internal hard parts are not terribly different from today, but the accessories and lubricants ARE. That's my real point.

I use a 1966 engine as a daily driver. I rebuilt it several years ago and went back to a very stock configuration in all regards. The biggest deviation from box-stock is that it has electronic ignition (a $100 investment and about 2 hours work) and that it has hardened valve seats in the head (which only raised the cost of the overhaul by about $50) It now gets about the same maintenance schedule as my wife's 05 PT Cruiser. I recently had an oil analysis done on both, and the old engine only had one wear metal that was higher (iron), probably attributable to the fact that it's a 7+ liter V8 with more than twice the ring-to-cylinder friction area and has the same volume of oil. Its copper and lead wear numbers were actually LOWER than the 2005.

(raising hand...)

I had another engine (1966 383) that I converted to electronic ignition, but it still burned 2 exhaust valves. At the time I was doing a great deal of sustained high-speed driving with it. From the other old car drivers I've talked to and my own experience, sustained high speed operation is *much* harder on non-hardened valves than city driving. Especially if you're starting with a higher-compression higher-power old engine than something like a base slant-6 or 318.

I had a third engine (1969 440) in a restoration project that didn't have any burned valves and still had great compression, but when I pulled the valve covers for some work (all the valve umbrella seals were rotted from age) and laid a straightedge across the valve stems, they were all at randomly different heights- lots of recession on many of the exhaust valves. So my quick saturday morning valve seal swap turned into a valve job and more hardened seats. Actually, it cascaded into months of work I hadn't planned to do for another year or so, but that's pretty typical for my projects it seems... ;-)

You can't possibly believe that.

Steve wrote:

That's more or less true, but the question was what causes the wear on internal engine parts. It has been shown that leaded gas at the levels used in the 60's causes significant increase in soot and ash and some increase in salts and acids in engine lubricants. And the difference is not anywhere near insignificant in terms of engine wear.

So these are just case hardened seats not stellite?

That's not evidence. Hell I know somebody with a 2003 subaru that burnt a valve at 60k. What does that prove?

The government of Thailand did some testing when they were deciding to switch over to lead free gas back around 1990. They ran engines from lots of different manufacturers (all asian and european) under high speed heavy load conditions (since that was the only circumstance where lead is supposed to make a difference). They found to there surprise that some valves in some engines without hardened valve seats held up better with no lead gas than others with hardened seats. Across the board they came to the conclusion there was no significant benefit to valves from lead. They also at the same time tested the additives that are added nowadays to European lead free gas that are supposed to replace the valve coating action of lead and found no significant benefit with those additives either. The only thing that has been proven conclusively is that lead raises octane.

I met a guy in the 70's that ran a volkswagon only repair shop. He was from germany and VW factory trained in germany. He had been working on VW bugs for 20 years. He claimed that none of his regular customers had ever burned a valve in a vw beetle engine that he maintained regularly. In fact he would guarantee it. Many of them getting over 200k without any engine trouble. His secret he said was a tuneup and oil change every

1500 miles. I told him that was a pretty tall claim given that those engines had a reputation for needing a valve jobs or more consistently at 60k . He said that was easy to explain: at about 60k the diaphragm in the vacuum advance would develop a leak. After that happens, drive it another 5-10k and the next stop is the junkyard or an engine overhaul. So the next time I was at a junk yard and saw a bunch VW bugs sitting in the same area and I ask if they would mind if I did a little snooping around in the beetle section. I checked about 20 vehicles and not a single one had a working vacuum advance. So after that whenever I happened to be at a gas station or a service garage or met anyone who claimed to be a mechanic I asked if they ever heard of a vacuum advance go bad on a VW or any other car for that matter. I never met a single mechanic who ever heard of a vacuum advance going bad. A few were honest and said they never had bothered to check if they worked or not. but the vast majority just blustered something like "oh No those never go bad they will last the life of the car" I guess that's sorta true. I can tell you for a fact that sustained high speed driving with a bad distributor or bad carb has a whole lot much greater impact on valves than lead or hardened seats. Running too much fuel or too little fuel or too advanced or to retarded spark at sustained high speed driving is going to make the issue of what kind of valves or seats or fuel additive completely irrelevant. The only significant effect that lead ever had on fuel was its effect on octane.

-jim

And of course elemental lead and mercury have an entirely different toxicity level than lead and mercury compounds. Handling or working with metallic lead is very different from eating lead compounds in paint, for example. A senior co-worker tells of how he used to bite the end of leaded solder wire to flatten it when he was fabricating circuits back in the 50s, and in my own generation we used to play with balls of mercury dipped from the open-beaker barometer in the school science lab. I don't recommend either practice and I'm glad we're more aware of toxins these days, but it does make me laugh my head off when someone panics and practically calls in the hazmat squad over the breaking of a compact fluorescent lamp. :-p

THAT is the single most overblown piece of misinformation out there. A substantial percentage of the cam failures initially attributed to inadequate ZDDP were in fact probably related to substandard material and processing of a whole lot of lifters and cam blanks. That's a risk when you're down to only one or 2 vendors still making flat-face lifters...

I'm running my flat-cammed Jeep and 1966 440 on SM-rated modern motor oils just fine. So long as the cam is properly broken in (the first

20-minute run-in) with the proper break-in lubricant, ~800 PPM of ZDDP is PERFECTLY good for everything short of extremely high-lift high spring-pressure cams. And there are other additives now being used to compensate for ZDDP. Don't forget that there is *still* a flat-tappet cam test required for any oil to get an API rating, including the "low phosphorous" SM rating.

Probably true, but then that falls in the same category as 60's oil not being good enough to use in a weed-whacker these days. My whole point was: given that these engines lasted >100k miles back then, it should be no surprise that modern engines last even longer. Furthermore, OLD engines built to OLD ENGINE SPECs also last far longer on today's fuels and oils, even with carburetion still in play instead of fuel injection.

Beats me, I subbed that out to the machine shop. They're an over-the-counter part specifically for vintage engines. Pressed in, just like modern hard seats are done.

There are plenty of burned valves out there, not just mine. There is also a known, understood, and well-described failure mechanism when the valve seats are not sufficiently hard (microwelding leading to roughness and erosion, leading leakage, leading to "torching" through the valve/seat junction under peak combustion pressure). The fact that SOME engines (probably the majority, in fact) never had trouble with unleaded fuel doesn't invalidate the need for hard valve seats.

Having worked with software engineers who previously spent a fair chunk of their career fixing Y2K problems before Y2K, I not only believe it I KNOW it.

Anyone that thinks Y2K wouldn't have been a problem if corrective measures hadn't been put in place is, frankly, clueless. It wasn't a problem because a huge effort was committed to fixing it in time.

I appreciate your opinion. A lot of work WAS done, and a lot of money was spent, and in the end there wasnt much of a problem, if any.

And the millenium passed, there was no apocalypse, no battle of Armageddon. The next end of the world scenario, I understand, is supposed to be

11-11-09, after which we will focus on the Mayan predictions.

Yes, I can. And I do. Here's an example:

And, of course, that's the smallest estimate I've seen by a wide margin. Here's another, quoting the Commerce Department at $100B.

I guess we can argue about whether these numbers are "huge" or not, but not about how badly broken things would have been if it wasn't spent.