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I'm buying an original 66 Fairlane 500 with the 289 two barrel carb. The guy that owns it now has been using a lead subsitute in the gas each time he fills up. The motor has never been torn apart so it has the soft valve seats.
My question is this. If I use this car just for driving to shows and putting maybe 3000 miles on it a year, do I need to continue using a lead additive to the gas. Or, is this unneccessary. If it will do damage, how long would it take to show up. Jim
 

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I'm buying an original 66 Fairlane 500 with the 289 two barrel carb. The guy that owns it now has been using a lead subsitute in the gas each time he fills up. The motor has never been torn apart so it has the soft valve seats.
No, it has hardened exhaust valve seats. They all do since long before unleaded gasoline. Do a search on here for threads about it, but the bottom-line from extensive lab research is that unleaded fuel has zero to do with how long the valve seats last. It's all about avoiding over-rich AFRs and retarded timing - the two most common factors (of about 7) for seat and valve damage. This is especially true at cruise speeds, such as if your vacuum advance is not working properly, as many are not after 40 to 50 years.
My question is this. If I use this car just for driving to shows and putting maybe 3000 miles on it a year, do I need to continue using a lead additive to the gas. Or, is this unneccessary. If it will do damage, how long would it take to show up. Jim
Lead substitute is a waste of money. Spend the cash on good parts and full tune-ups. Not many shops these days know how to really do that, and it's far more than just changing plugs and various parts and filters. It's tuning to adjust for wear, newer fuels, etc. Follow your Ford Service Manual and leave yourself a full weekend to do it the first time. You will gain power, mileage, and extend your seat life.

David
 

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Discussion Starter #3 (Edited)
Thanks David. I've never bought a car that was original this old before. It's got 37K miles on it and the paint still looks good and the interior looks new.
I've always had to rebuild everything and I really didn't know about the valve seats. Thanks again. Jim
 

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I thought leaded gas was to lub the cylinders and valves. My understanding was the older motors needed the lead for lubing. I thought thats one reason why my 62 had burnt valves because the first owner used unleaded, espicalley when leaded was taken off the market.

After I did the valve job on my 62 (the motor is from 1966), I6 200ci. I too used lead sub in {almost} every fill up...

So, your saying, even for me, leaded sub is a waste of money?.
 

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Correct. There are a lot of urban legends about 'lead in fuel'. I won't go into it here as there is extensive info on this site about it, with the info coming from large leading engineering and engine labs, along with explanation of some of the stories you hear and how they are not valid. Note that if you have done a valve job, the original seat hardening may have been ground-off. In that case you may see faster seat wear, but the unleaded still has nothing to do with that. This all relates to the old fallacy of "needing hardened seats installed." Factory seats are hardened, and the only time new hardened seats are needed is if the seats are damaged, worn or re-surfaced to the point the old hardening is removed. That's obvious though, as grinding that deep hurts power by sinking the valves anyway. Save your money, keep it tuned, and save more money.
:tup:
David
 

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I redid a set of DOOE heads. Pocket ported them and did a compitition valve job. Ran the engine over 160K before removing the heads. Valves and seats were fine. Fully ported them and installed larger valves. Think they have about another 30K on them. At about 20 K had to remove the heads and clean them and the piston tops because of some bad fuel I filled up with. No noticable wear just the nastiest deposits I ever encountered after 60 miles of driving.
 
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