Leaded Fuel?
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Posting Guru
Joined: May 2004
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From: Spokane WA
Leaded Fuel?
pretty much, im askin for a history lesson here. i know you cant get it at pumps any more, but i was just wondering about it. someone was saying that my 390 was made for leaded, even though its remanufactured. also, what are the advantages/disadvantages of lead? anything else anybody knows would be cool to know too. thanks
Elder User
Joined: Feb 2004
Posts: 835
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From: Fort Rucker, AL
If whoever rebuilt your motor had hardened valve seats put in your heads, you will be fine. Somebody correct me if I'm wrong, the lead would act like a buffer during the combustion and protect your valve seat. Unleaded fuel has no buffer therefore is hard on the valve seats. There are lead additives you can put in your tank if you have older heads and they weren't hardened. You can check your heads and see what the cast number is. If it's a D2 or later, the seats were hardened anyway.
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
What happens is, when your engine is running your exhaust valve gets red hot. When it's on the seat, it kind of micro-welds itself to the seat, pulling off small microscopic parts of the seat with it. The lead coated the parts to prevent this. Without the lead, valve seats wear out in about 20,000 miles. The solution is hardened exhaust valve seats. I resists this kind of wear much better than the standard cast iron of the head.
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
Originally Posted by EconoDan
If the engine runs fine and it's old enough - they'll be hardened and lead-soaked already.
Basically, you don't need leaded fuel anymore. Run it on unleaded. If you hear pinging...bump up the octane.
Basically, you don't need leaded fuel anymore. Run it on unleaded. If you hear pinging...bump up the octane.
