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I was just reading an article on lead additive for Pinz that have the big red "X" through the sticker on the dash... more or less, it says it needs a lead additive. Good thing i read it!
So what happens to the valves over time? Could this lead to the smoking im experiencing? (BIG puff at start, then more at idle and initial take off).

Whats it cost to repair any damage to the valves?

I'm sure someone can give you a better technical explanation, but here's my understanding:

The lead kept the burn in the cylinder from being too fast and too hot. In older vehicles, which were built for leaded fuel, unleaded fuel will burn too fast causing damage to the head/s at the valve seats. A fairly common modification is to replace the valve seats with hardened ones, thus allowing the engine to use modern gas.

From what I remember on previous discussions, it seems undecided whether the seats in the Pinz are damaged by unleaded gas or not. Probably someone who has torn down several Pinz engines would have better first-hand knowledge than I do.

FWIW, I always add lead additive. Seems better safe than sorry.

I haven't used any additive. over 80k still going strong. I am ready for rings tho.

I use a lead add. when on long trips. Not for just arround town stuff.
This was recommended to me by Dennis at LinDen, but then the kind of long trip I'm talking about is from Seattle to Denver.

Morris

my understanding on it was, that "BU"(Before Unleaded) the addition of lead in the gas was to provide lubrication to the valve faces/seats(among other things). if you run no-lead gas without the lead additive, you'll get premature wear on the valve faces and/or valve seats. the permanent fix is supposed to be new hardened valves and seats which are capable of handling the "un-lubed" no-lead gas environment.

You do not need lead additives unless you want to use them.
I find all it does is attract more build up on the back side of the valves.
Most of these trucks have had rebuilt heads from the factory in thier lifetimes and have sufficiently hardened valve seats. As I do rebuild them fairly often I can say they can sometimes be a B*tch to grind. I end up truing seat stones for every head. The valves themselves are quite robust and I seldom replace one unless it has been burnt or bent
That is my experience and 2 cents

There ya go. My vote's on Jim's opinion. He's seen them firsthand. I guess I'll rethink my use. Thanks.

My 710 has decals by the filler and on the dash that warn AGAINST using leaded fuel! When I asked him, Thilo Kass swore up and down to not use any fuel containing lead.

Sounds like a case of who you ask is going to determine whether you use gasoline with or without lead?

I've put about 34,000 Km on my 710 over 6 years and never used additives. I just did a leak-down test and all cylinders were well within range, so that tells me that unleaded is OK.

I am by far no expert with these engines, but if you add some Marvels Mystery Oil to the gas, would that suffice for lubrication instead of the lead?

Jim's opinion is all I need. I used an additive on my first Pinz, but not on my last two.