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Leaded Gasoline
Just a basic questions...I have a 1972 Mustang Hardtop with a 351C 2V (H-code). The engine was unrestored when purchased. Was this engine built for leaded or unleaded gasoline? Some internet sites are using 1971 as the cut-off date, but I remember using lead additive in 1973's. The owner's manual recommends at least 92 octane, but nothing else. Any help would be appreciated.

Thanks, Joe
no you do not need lead for these cars, they were made for regular gas.
To piggy back on 72HCODE response and provide a bit of amplification, the requirement for lead should not be confused with gasoline octane rating. Lead was originally used primarily to increase the compression ratios in an engine thereby generating more power. As an additional benefit, lead's additives help prevent the erosion of the valve seats.

Generally speaking, you will find that cars with low compression do not need leaded gasoline. For the high compression vehicles that previously required lead, a fix is in order through the addition of harden valve seats and/or octane boosters (to increase octane rating).

I believe 1971 was the last year that the 351C was manufactured with a requirement for leaded gasoline.

Hope this helps.

just get the highest octane gas you get at the pumps should be fine.I have a 1970 or 71 engine with closed chambers and I run it on 92 or 94 octane only.


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????? Do not worry about leaded or unleaded - Lead was used as a lubricant in the fuels prior to 1974 - 75 era. Primarily it lubricated the valve seats. When lead was removed for obvious health reasons, the car hobby and the general public were concerned about the long term effects of this move. Several "additives" were introduced to add "lead" and lubricants into the fuel.

Several studies were done showing little valve seat recession actually taking place. It took over 50,000 miles of driving to induce measurable recession. For the amount of driving we actually do in our classic Mustangs It is much ado about nothing IMHO.

Heads did NOT have hardened seats from Ford until '75-76. When I went through the heads on my engine a couple of years ago about 35k miles after the PO had it gone through the seats looked pristine. I did cut the heads and install hardened seats at that time since the equipment and parts were available for my use at the time.

I hope this helps.

To summarize Don't worry about it.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

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