unleaded or not

[John McFarlane]

So. After so long, and so many threads, what is the general consensus on using unleaded/lead replacement fuel in an old engine. Specifically a 28 Chev....??

[Guest]

Hope I can be of some help as this "problem" concerned me too and I have since learned a great deal. As you may know lead was an additive to gasoline, developed to eliminate "knock" and "pinging" particularly in higher compression engines, it was also discovered that it extended valve seat and guide life in modern, high compression engines particularly on vehicles of the '30's and later. The main culprit according to British tech articles, {they seem much more thourough than we do in the states} is valve seat recession, particularly the exhaust valve, engine machinists have confirmed this to me as well, however your chevy's motor was not designed to use leaded fuel. the effects of most lead substitutes may be on the imagination of the user while hardened valve seats and bronze guides are indicated where a high compression mill like an overhead valve v8 sees much hard use, a friend has a '51 flathead 6 that is driven daily and after 2 years the valve adjustments have not changed appreciatively and he uses straight unleaded. Many honest hobbyists have been victimized by people doing "unleaded conversions" on cars that really do not need it. my final advice? read,read, read and get as much info that you can, but don't worry about your chevy, check the valve adjustments periodically if you like but you're in no danger. Carleton

[The Old Guy]

I have put over 90,000 miles on my straight eight Buick engine ,and have not used any additives ,and it still runs just fine. It has hydraulic lifters ,so I haven't had to check the valve clearances ,but it must still be within tolerance as it runs great!

[Guest]

Tetraethyl lead was developed by Charles Kettering in 1924. The Ethyl Corporation was formed about that time to produce and distribute that product. I didn't come into <B>GENERAL</B> use until some time after that and engines of that era were not designed specifically with tetraethyl lead in mind.<P>Low compression engines just do not require lead and the engines of that era were certainly "low compression". Also remember that an engine built before the development of tetraethyl lead cannot possibly require something that was not in existence when it was built. <P>The hoopla that you "must use a lead substitute when using unleaded gas" is a great marketing tool and sells a lot of unneeded product. <P>The same goes for octane boosters. The octane rating for regular gas here at 6000 feet is 85. That is a lot more octane than the pre WW II automotive fuels ever had.<P>The Luftwaffe in WW II operated on 86 octane fuel throughout the war, and that is a bit lower than regular fuels sold at sea level locations today. In the late '40s a friend and I flew his PT 19 on "Blue Sunoco" taken right from the pump at a gas station, to jerry cans, to the airplane, and we are both here to tell about it. With today's fuels as used in <B>Antique</B> vehicles, not muscle cars and the like, octane just isn't a problem. <P>Again, just my non professional opinion based on study of the subject while serving as the AACA Technical VP in 1984, the year when lead was first being removed form our gas.<P>hvs<p>[ 05-02-2001: Message edited by: hvs ]

[Guest]

hvs brings up an interesting point regarding octane, many older cars with low compression motors suffer from vapor lock because of the higher octane gas which they were not designed to use, my '15 stellite would stall regularly after it warmed up until I blocked off the carb heater! same thing on my '27 buick.

[Guest]

LI ~ I did that with my '24 Buick 20 years ago. A while back there was a rather in depth discussion of the subject of carb heat here on the forum. It was started by Julio from Brazil. I believe it had to do with his '28 Chev. and I think it began with a question about the air cleaner.<BR>~ hvs

[The Old Guy]

I pulled a 17 foot 1935 covered wagon travel trailer to California from Michigan in the 70s and I ran 5 gals of diesel and 15 gals of regular to do away with the vapor lock and it worked well! those old 41/2to 1 engines would darn near run on soft coal.I was running a 32 Buick 90 series and it did a fine job. I ran over 6,000 miles and never had a major problem.

[novaman]

The unleaded gas in our old cars really isn't much of a problem considering the low annual mileage. What I had done to my last three 6 cyl. engines when I rebuilt them was to have hardened valve seats put in the head, especially since the Ex. seats in all # 6 cyls. were sunk and needed replacing. With the hardened seats I won't have any problem. I wouldn't change the seats unless you are in need of a engine rebuild or a valve job. I did mine in a race car machine shop. And it is really the exhaust seats that take the unleaded gas takes a toll on.<p>[ 05-02-2001: Message edited by: novaman ]

[Guest]

It is interesting how this forum seems to come full circle back to subjects previously discussed. <P>I believe a while back there were some pretty in depth discussions on methods of eliminating vapor lock. I know I posted my experience in using diesel/gas mix in my '41 Cadillac. Joe, you went to a much higher percentage of diesel than I did, but then I believe that early 30's Buicks had a heat riser on the intake manifold which would have aggrevated the condition were it not blocked off. I have such a device on my '24 Buick and I had to block it off.<P>I think that previous thread started out discussing fuel pumps on a '30's LaSalle and progressed from there into vapor lock discussion.<P>hvs<p>[ 05-02-2001: Message edited by: hvs ]

[Guest]

Okay, I'll throw my 2 cents in here. I have a 48 Packard with a 7:1 compression ratio. I was originally using premium unleaded and vapor lock was a regular occurence. I did some research and found the highest octane in 48 was 76. Well, I switched to regular and never had a problem since. I do use a gas additive made for industrial engines too.

[Guest]

Here is the answer for Phillips, don't about the other. <A HREF="http://phillips66.com/about/why66.html" TARGET=_blank>http://phillips66.com/about/why66.html</A>

[Guest]

HVS: You are right about Union 76. At one time they had the highest octane in the market.

[Guest]

Very interesting and informative information supplied by two of our DFers.<P>The Phillips "66" origin is clearly set down by the company itself, and disproves the story so many of us had heard for so long about it being octane related.<P>The idea that the Union Oil Company's "76" was octane related had never crossed my mind, as I had never heard it said that it was octane related. It wasn't until today when Chris mentioned the 76 octane being the highest in 1948 did I begin to wonder if it, like "66", might be an octane number.<P>So thanks to the collected knowledge made available to us on the AACA Discussion Forum, we have laid one myth to rest and for me at least, added some new knowledge on automotive history.<P>Thanks to both Bill and Chris. ~ hvs

[ply33]

I had heard that Phillips 66 was named after Highway 66 which is pretty close to what the company web site says.<P>I had heard that the 76 in Union 76 was for the octane. Unfortunately I don't have any confirming evidence and the company web site at <A HREF="http://www.76.com/" TARGET=_blank>http://www.76.com/</A> seems to have nothing about company history.

[ply33]

There is a <a href="http://www.faqs.org/faqs/autos/gasoline-faq/part1/">Gasoline FAQ</a> available that is fascinating reading. Has more in it than I can understand. Unfortunately, it does not tell if the 76 in "Union 76" is for the octane.<P>Here are some interesting bits from the FAQ:<P>On the topic of where octane ratings came from:<blockquote>In 1927 Graham Edgar suggested using two hydrocarbons that could be produced in sufficient purity and quantity [11]. These were "normal heptane", that was already obtainable in sufficient purity from the distillation of Jeffrey pine oil, and " an octane, named 2,4,4-trimethyl pentane " that he first synthesized. Today we call it " iso-octane " or 2,2,4-trimethyl pentane. The octane had a high antiknock value, and he suggested using the ratio of the two as a reference fuel number. He demonstrated that all the commercially-available gasolines could be bracketed between 60:40 and 40:60 parts by volume heptane:iso-octane.</blockquote><P>If I understand this correctly, the implication is that the octane ratings of gasoline in the late 1920s ranged from 40 through 60. If you read the FAQ you will not that there are many ways that octane can be and have in the past been measured, so it is not clear how these numbers map into our modern numbers. But the later in the FAQ is says:<blockquote> In the 1920s, typical gasoline octane ratings were 40-60 [11], and during the 1930s and 40s, the ratings increased by approximately 20 units as alkyl leads and improved refining processes became widespread [12].<P>For a typical carburetted engine, without engine management [27,38]:-<table><tr><td>Compression<BR>Ratio</td><td>Octane Number<BR>Requirement</td><td>Brake Thermal Efficiency<BR>(Full Throttle)></td></tr><tr><td>5:1</td><td>72</td><td>-</td></tr><tr><td>6:1</td><td>81</td><td>25 %</td></tr><tr><td>7:1</td><td>87</td><td>28 %</td></tr><tr><td>8:1</td><td>92</td><td>30 %</td></tr><tr><td>9:1</td><td>96</td><td>32 %</td></tr><tr><td>10:1</td><td>100</td><td>33 %</td></tr><tr><td>11:1</td><td>104</td><td>34 %</td></tr><tr><td>12:1</td><td>108</td><td>35 %</td></tr></table></blockquote><P>There is a bunch more info about things like what lead is, how gasoline goes bad, etc.<p>[ 05-04-2001: Message edited by: Tod Fitch ]

[Tom Deering]

You guys piqued my curiosity about the origin of "76" in the former Union Oil of California logo.Santa Paula, Ca. is an old oil town where Union Oil was very active in the old days. There is an old building there that was erected by 3 oil men in 1890 that is now called the California Oil Museum. We local types always referred to it as the Union Oil Museum. <BR> The following is their response to my E-Mail inquiry this afternoon:<BR>"The company was looking for an easily remembered logo that was visually attractive.They tried several images and the 76 was decided to be the best. It also had a patriotic association which the company liked. It was not chosen for the octane. It came out in 1932".<BR> Like my wife says: "Whatever useless garbage I don't already have commited to memory; I'll go find it".<BR> Tom

[Guest]

Can anyone shed any light on the story I have heard for years?<P>I have been told that Phillips 66 was actually the octane rating of a fuel offered by Phillips Petroleum and by using the "66" in advertising they were boasting of its "high" octane rating.<P>Now, did Union 76 have the same origin? Chris' post about 76 octane in '48 makes me wonder. ~ hvs<p>[ 05-04-2001: Message edited by: hvs ]

[Guest]

OK ~ So now we know. Octane number had nothing to do with either the 66 or 76 names.<P>Tom is right. We all now have some additional useless information available. At least it is accurate useless information. Thanks Tom! <P>hvs

[Guest]

Tom & Howard: I appreciate this info. It is intriquing. One can have fun with this useless, but, accurate data. When conversing with someone who thinks they know it all and you relate such "garbage", they are put in their place. They know nothing of the subject and respect you for knowing such a detailed subject.<P>99% of the time, the person would not have the time/interest to look up the details to counter what you stated.<P>Regards, Peter J.

[Guest]

Hey Deering, I think you got the bum steer on Union 76. Check out this website on the history of the Union 76 orange ball. You are right about the year (1932) but it was indeed to hail their 76 octane gas.<BR> <A HREF="http://www.osbornauto.com/76balls.htm" TARGET=_blank>http://www.osbornauto.com/76balls.htm</A>

[ply33]

Well, if the gasoline FAQ is correct you would want a mid-70s to low-80s octane to put in a car with a 5.5:1 to 6:1 compression ratio. And the typical engine compression ratios were approaching that in the early to mid 1930's.<P>So it is possible that a 76 Octane gas would become available in the early 1930s.<P>However, there is the question of reliability of sources. A fellow selling 76 antenna balls making a statement with no references does not lend credibility.<P>It is interesting that the year 1932 is mentioned on that. It would narrow down a search for a more authorative answer.