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Unleaded fuel compatibility question

P peterfenlonMember
I ask if the Cleveland engine is OK to use unleaded fuel without having to fit new hardened valve seats?

I bought 3840 in January and will soon be able to start work on fitting new Holley carb fuel pump and get it ready for a MOT over here in England.

A new owner, so forgive the lack of nouse.
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dougmdougmMember
It also acts as a lubricant for the valve train


"Tetraethyl lead works as a buffer against microwelds forming between the hot exhaust valves and their seats.[4] Once these valves reopen, the microwelds pull apart and leave the valves with a rough surface that would abrade the seats, leading to valve recession. When lead began to be phased out of motor fuel, the automotive industry began specifying hardened valve seats and upgraded exhaust valve materials to prevent valve recession without lead."

If your engine is all original inside then an additive is a good idea.

Doug M
George PGeorge PAdmin.
Peter the short answer, it is OK to use unleaded fuel.

I'm assuming the engine in your Pantera has flat top pistons & open chamber heads, i.e. nominal 8.7:1 static compression. If so, and it is equipped with the original camshaft, it has 6.4:1 dynamic compression, and will operate on either 91 or 93 octane fuel (RON rating). I believe the lowest octane gasoline available in England is 95 octane (RON rated), so your Pantera's engine should be more than safe in regards to pre-ignition with "regular" gasoline.

The valves in the US manufactured 351C engines were aluminized as a way to cushion the valve train and thus substitute for the lead in gasoline. This aluminizing process is what made the valve heads brittle, and has resulted in the tendency for the valve heads to occasionally crack & fall off the stems. The valve seats in the open chamber heads were also hardened from the factory. The engines in the US have been operating without lead in the gasoline for decades, without increased valve train wear. This is fact that I and millions of other Ford & Mercury owners have proven via decades of operating our engines on US gasoline. Therefore I can assure you with 100% certainty that the engine in your Pantera does not need additives or hardened valve seats.
P peterfenlonMember
quote:
Originally posted by George P:
Peter the short answer, it is OK to use unleaded fuel.

I'm assuming the engine in your Pantera has flat top pistons & open chamber heads, i.e. nominal 8.7:1 static compression. If so, and it is equipped with the original camshaft, it has 6.4:1 dynamic compression, and will operate on either 91 or 93 octane fuel (RON rating). I believe the lowest octane gasoline available in England is 95 octane (RON rated), so your Pantera's engine should be more than safe in regards to pre-ignition with "regular" gasoline.

The valves in the US manufactured 351C engines were aluminized as a way to cushion the valve train and thus substitute for the lead in gasoline. This aluminizing process is what made the valve heads brittle, and has resulted in the tendency for the valve heads to occasionally crack & fall off the stems. The valve seats in the open chamber heads were also hardened from the factory. The engines in the US have been operating without lead in the gasoline for decades, without increased valve train wear. This is fact that I and millions of other Ford & Mercury owners have proven via decades of operating our engines on US gasoline. Therefore I can assure you with 100% certainty that the engine in your Pantera does not need additives
or hardened valve seats.


Thank you for your comments, and after reading Georges reply, I must say its a relief!
brilliant forum.

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