What gas do pre-1974 LEADED gas cars run?

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Originally Posted by wowthisexists
So, leaded cars can use unleaded?
Then what was the point of the lead if it's not even needed ?

I guess the issue with many of these engines was that lead helped to lubricate and cushion certain parts by forming a protective layer. It was just something that engine makers took advantage of. However, the primary reason for lead was that a small amount was a highly effective octane rating booster. If the parts weren't designed around this, they would still work fine with unleaded with an adequate octane rating.
 
Both of mine have hardened valve seats. The MG got them a few years ago, while the Marina got them back in the 80s.

The MG is at 9.5:1, and runs top tier 93 along with the timing advanced a bit over standard(I could run it on 89, but don't like how much I have to retard the timing, and the accompany low RPM power loss). The Marina is still at its emission-strangled 8.0:1, and gets whatever cheap 87 I want to put in it.

From about 72 onward, the British "A" and "B" series engines had induction hardened valve seats from the factory(series 18V on the 1800cc B engine). This, along with some other smog accoutrements and the associated temperatures, tends to cause cracking from the exhaust seats. If one is caught before it cracks, or at least cracks badly, usually it can last more or less forever if its fitted with a proper hardened steel insert seat.

I would not be averse to the occasional use of 100LL if I were running something without hardened seats.
 
There are many lead substitute products available, pick a reputable name brand and dose your fuel as directed. You may need to use a higher octane level, but maybe not. I understand some of the old school gasolines back in the day had lead to increase the octane/anti-knock index. Experiment a bit and use whatever works.
 
Must've missed this thread....

If you do use a lead substitute, get one that's been proven to work. One of the British historical vehicle groups did extensive testing on lead replacement additives and only recommended a few. Sadly, not many were available here, but Redline is and was one of the recommended additives. That is all I use, plus the very occasional shot of 100LL if I have one of the oldies with me as I preflight.

Google lead substitute test and you should be able to find the British study.
 
Found it, and way back when I asked Redliane as was told that their lead substitute here is the same as in the UK:

"Accept These Substitutes
The following additives have been tested as being effective against valve seat recession, and are approved for use by the Federation of British Historic Vehicle Clubs.

Delta Oil

Red Line Lead Substitute Employing sodium to deliver the goods, Red Line Lead Substitute is said to clean intake systems, carburettors and injectors in addition to preventing valve seat recession. It was developed in the U.S.A. Delta Oil Ltd., Unit F1, Market Overton Industrial Estate, Market Overton, Rutland, LE15 7PP. Tel. 01572 768311.Website: http://www.redlineoil.co.uk"
 
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