Fuel Question

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   Here is an article about leaded vs unleaded gasoline in older engines...

Leaded vs unleaded gasoline

I noted one part of the article inparticular that stated lead is really only beneficial on soft valve seat engines that are run at high load and  speed...this pretty much describes a boat engine perfectly.

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David F Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770	Post Options Post Reply Quote David F Report Post Thanks(0) Quote Reply Topic: Fuel Question Posted: July-27-2005 at 3:08pm
	Here is an article about leaded vs unleaded gasoline in older engines... Leaded vs unleaded gasoline I noted one part of the article inparticular that stated lead is really only beneficial on soft valve seat engines that are run at high load and speed...this pretty much describes a boat engine perfectly.

captan1 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-02-2004 Location: United States Status: Offline Points: 180	Post Options Post Reply Quote captan1 Report Post Thanks(0) Quote Reply Posted: July-27-2005 at 1:32pm
	I think the lead was to cushion the valve seats not the stems, I guess we can assume the smaller plugs are of a newer year with hardened valve seats.
	1978 Ski Nautique

Bhedbloom Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: December-01-2004 Location: United States Status: Offline Points: 116	Post Options Post Reply Quote Bhedbloom Report Post Thanks(0) Quote Reply Posted: July-27-2005 at 1:14am
	Rob, I have been using lead substitute in both of my boats for years due to the previously mentioned valve issue. It is pretty cheap insurance in my opinion, plus you can go to Wal-Mart and get a bottle of lead substitute concentrate with a self measuring top that will treat about 450 gal. for about $12.00. If CC said use leaded fuel they said it for a reason. $12.00 is a lot less expensive than a valve job. Happy Boating!
	Barry, South Carolina

marks Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: April-23-2004 Location: United States Status: Offline Points: 96	Post Options Post Reply Quote marks Report Post Thanks(0) Quote Reply Posted: July-27-2005 at 12:48am
	The 14mm refers to the spark plug thread size. The 5/8" refers to the wrench size. Supposedly, Ford changed the thread size from 18mm to 14mm at the same time they changed over to hardened valve seats.

JEFF KOSTIS Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: April-19-2005 Location: United States Status: Offline Points: 817	Post Options Post Reply Quote JEFF KOSTIS Report Post Thanks(0) Quote Reply Posted: July-27-2005 at 12:27am
	Yeah, for sure! I mix some 2 stroke oil in with the gas. It seems to work well. They use that in real old firetrucks with gas engines instead of the lead subsitute. They claim it works better. I cant be 100% sure however, but it seems to make sense.
	MUSTANG COUNTRY 1974 Mustang 17 1976 Mustang 17

RobG Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-07-2005 Location: United States Status: Offline Points: 31	Post Options Post Reply Quote RobG Report Post Thanks(0) Quote Reply Posted: July-26-2005 at 11:41pm
	Thanks everyone for your help. I can't help but wonder why they put the warning sticker on there if unleaded is OK. Oh, well!

David F Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770	Post Options Post Reply Quote David F Report Post Thanks(0) Quote Reply Posted: July-26-2005 at 6:51pm
	That is weird. I always thougth 5/8" plugs mean 351W and 14mm plugs mean 351C. 5/8" does NOT equal 14mm.

joel Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-18-2005 Location: United States Status: Offline Points: 9	Post Options Post Reply Quote joel Report Post Thanks(0) Quote Reply Posted: July-26-2005 at 6:27pm
	Rob I email PCM and this is email I got from them. I have a 83 SN 2001 I saw the same thing. Mr. Bissing, In reply to your inquiry your PCM Ford 351 engine will run fine with 87 octane fuel. If your engine has 5/8 (14mm) spark plugs, a lead additive is not needed. If your engine has 18mm spark plugs, then a lead additive would be needed. Please reply if you need further information on this matter.
	Joel

David F Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770	Post Options Post Reply Quote David F Report Post Thanks(0) Quote Reply Posted: July-26-2005 at 6:20pm
	Most people go ahead and use unleaded without issue. The theory is that lead lubricated the valve guides. So, if you use unleaded and eventually the engine burns oil on cold start-up, you can simply replace the valve guides with modern parts that do not need leaded fuel.

RobG Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-07-2005 Location: United States Status: Offline Points: 31	Post Options Post Reply Quote RobG Report Post Thanks(0) Quote Reply Posted: July-26-2005 at 5:12pm
	Hi, can somebody help me out? I've had my 1986 SN for about a month. The other day we were gassing it up at the marina and I noticed a sticker by the fuel filler that said 'use leaded fuel only'. I don't remember if there was still leaded fuel back then. Is this for real? Do I need to use lead additive? Thanks in advance, Rob

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