Does a 1974 Ford 351 Marine Engine burn leaded or unlead gas?

Question

This engine is in an old Chris Craft Dory, and I'm wondering if I have to replace it.

Answer 1

Put unleaded in there, you can't buy leaded anymore anyway. IF the valves need servicing after 10,000 hours you can cross that bridge when you get there.

Answer 2

All good answers...so there you have. Unless you have access to Racing fuel, you're gonna use unleaded. Yes, there are a variety of additives you can investigate and try. Likely you will need to look at valve and seat replacement down the road...or river so-to-speak. However...the engine is very reliable and low-tech and you won't be punching it hard...so it may outlive you on leaded gas...you'll be forewarned by blue smoke and oilly discharge at your exhaust.

Answer 3

It was designed for leaded gas. It will run on unleaded until it wears out. If you want add moroso fuel additive.

Answer 4

Your engine can burn unleaded gas. Since the only leaded gas you can get is aviation gas or racing gas, you don't have much choice. When it needs rebuilding have hardened valve seats and stainless steel valves installed in the heads. It will do fine on unleaded gas.

Answer 5

There is additive you can get at the auto parts store to help it out>Don't use reg> Use mid range>93 octane>>

Answer 6

originally burnt leaded, but you cant buy it anymore so use unleaded and put some Marvel Mystery oil in the gas.  the oil helps to lubricate the valves (just like the lead did in the old gas)