"Grunff" wrote in message
...
:::Jerry:::: wrote:

I'm not so sure about that, on a 30 year old engine that is, lead was
the
upper cylinder lubricant in those days and many a valves life depended
on
it, current engine technology is such that lead is not required.

There is a big difference berween the role played by lead and that
played by hydrocarbon lubricants.

The purpose of the lead was twofold:
1. It reduced knocking
2. It formed a coating on the valves + seats, and prevented the valves
from welding to the seats, thereby causing valve seat recession.

Hydrocarbon lubricants act to lubricate the valve stem/guide, and the
piston/bore.


A mid '70's engine might well last longer if Redex is used, even with
LRP.

If it's an iron cylinder head, unless it has hard seat inserts it needs
either leaded or LRP with an alternative additive, otherwise the head
will only last a few thousand miles.


A far to simplistic explanation, and what the head is made out of is
irrelevant.