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Like any other older car, the lead was needed to lube the valve guides. Depending on the miles on your Z, most likely the exhaust valve guides are already shot... we've been unleaded for a while. The additives work well, but when you decide to rebuild, the machine shop will hook you up with some nice hardened guides.
 

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Discussion Starter · #3 ·
> Like any other older car, the lead was
> needed to lube the valve guides. Depending
> on the miles on your Z, most likely the
> exhaust valve guides are already shot...
> we've been unleaded for a while. The
> additives work well, but when you decide to
> rebuild, the machine shop will hook you up
> with some nice hardened guides.

What about the seats,are they already hard enough?
 

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Read

The lead was not used to lubricate the valves it was used to help the valves seat and seal. The soft bronze seats needed the help. You will not be in any dire emergency to have the seats replaced, but if your head is off, a valve job and some hardened seats would not be a bad idea.
 

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Re: Read

> The lead was not used to lubricate the
> valves it was used to help the valves seat
> and seal. The soft bronze seats needed the
> help. You will not be in any dire emergency
> to have the seats replaced, but if your head
> is off, a valve job and some hardened seats
> would not be a bad idea.

I'd just like to add that it's only the intake seats that need to be replaced, the exhaust seats are already hardened. If you have the head off you can tell if they need replacement because the seats will be sunken in. This throws off the valve train geometry slightly as well as slighly lowerng your compression ratio. Damned EPA always has to find something to bitch about to justify their existance. Suppose you could run 100 lowlead avgas or have they gotten rid of that too? (haven't checked into that in a few years)

Anyways, the machine work to replace the seats isn't cheap, but it's not too bad and look on the bright side, you'll probably only have to have it done once as long as you own your Z. (and it's not a bad idea to replace the guides either since you've got it of and they're gonna be 20+ years old on most Z's.) I had mine done last summer on my replacement head for the one I cracked so happily my cyl head is now Y2K compliant. :)
 

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Discussion Starter · #6 ·
Re: Read

> The lead was not used to lubricate the
> valves it was used to help the valves seat
> and seal. The soft bronze seats needed the
> help. You will not be in any dire emergency
> to have the seats replaced, but if your head
> is off, a valve job and some hardened seats
> would not be a bad idea.

Thanks for info!!!
 
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