leaded / unleaded...

[Stude-Dude]

what's the general consensus here regarding "lead substitutes" ???

thanks in advance...

[tutone63]

Well, my dad swore by it...I don't use it as much as I should. But the general idea, I believe, is to lower heat and raise octane, even if the octane raise is small. But the biggest thing I think is the lowering of the heat for the older style valves in these engines we use. My dad won't fill up his 1968 pontiac without adding some.

[Corvanti]

never used the lead substitute, but definitely use zddp in the oil!!!

[Bud]

I don't believe that the lead substitutes do much to take the place of Tetra Ethyl Lead except lightening your wallet a bit. Lead was a cushion between the exhaust valve and its seat. Beside preventing detonation it prevented the microscopic welding that occured between the valve and seat every time the valve opened and closed, which over time causes valve guttering and valve seat recession. The only permanent fix for the removal of TEL from the gasoline we use, is either replacing the valves with stellite exhaust valves used in the R engines and using a hardened valve seat or locate a source of avgas as it still has TEL in it as aircraft engines won't tolerate the use of unleaded gas in most cases. When I can get avgas, I add about 5 or 6 gallons to a tank of uneaded. Avgas is also 100 octane so it has better detonation resistance. I don't however recommend using straight avgas as it has different additives in it such as a good amount of toluene. Bud

[jackb]

hardly applicable today (lead additive) unless you are driving your car/truck hard almost daily.....I bought into not using lead some years ago in me 62" Champ truck daily driver. Worked it as a truck for 10 years and 112K miles......Once apart I found a cracked head and my exhaust valve seats completely shot....NOS heads are in South Bend...they were cheap

[Mike Van Veghten]

Save your money and install hard exhaust valve seats on your next rebuild.

Or...if your Stude is just a drive to a show and home...you can save that money too..
But if you drive a coupla times a week or on long drives every now and then...yes, put hard seats in the heads.

Mike

[1954khardtop]

Like Mike said, install hard seats DURING YOUR NEXT REBUILD. Years ago when leaded gas became unavailable my brother in law tore his perfect running flathead Harley engine apart to put hard seats and stainless valves in. I told him he just did a valve job to prevent having to do a valve job. Didn't make sense to me. I waited 'till I had the engine down on mine ten years later (for rings, valves still good!) and did it then. He uses lead substitute and top oil in his, I don't. We haven't seen any difference in valve and seat life.

[Nelsen Motorsports]

My brother's 59 Chevy was, until 07', driven religiously by my uncle every day 5 miles to work for 20 years. The engine has never been apart and the 235 still purrs after 50-60,000 miles (o.d. broke right at 40,000). The cars has always been run with 1/2 bottle of lead every other tank. It lets out some greyish smoke when cold, but otherwise runs like a champ.

[53commander]

I run AV100ll fuel in everything I own that doesn't have a catalytic converter. Not only will the lead save your non hardened valve seats but there is no Ethanol in it to ruin the carb after sitting awhile.