When leaded when from Europe a few years ago there was much discussion on
this topic. One input, reputedly from BMW, was that if an engine had used
leaded for at least 40k and not had new valves or recut seats (grinding was
OK) there would be enough lead leached into the valves and seats to last
'the normal service life of the engine' (whatever that might be). This is
known as lead memory. Lead Replacement Petrol has been available in the UK
since then, which is said to be dosed with half the ideal level of an
additive which has been proven to protect against recession. Why half?
Apparently because if a car with a cat uses it it won't suffer damage,
whereas with a full dose it would. Whoever said that didn't explain how you
got a big LRP nozzle into a little unleaded filler hole, but never mind.
LRP is said to be satisfactory unless you consistently use the car at high
speeds and/or heavy loads over prolonged distances. All of which tends to
support the opinion that a classic car used for occasional cruising at
moderate speeds, probably doesn't need it, especially when users can obtain
protection additives which they can use at the ideal dosage. 'Daily driver'
or not probably doesn't cover it, it all depends how it is used when it *is*
being driven.
PaulH.
----- Original Message -----
From: "David Macedonia" <david.macedonia@verizon.net>
To: "MG Mailing List" <mgs@autox.team.net>
Sent: Thursday, January 08, 2004 2:54 AM
Subject: Hardened Valve Seats
> While we're on the topic of hardened valve seats, can someone tell me how
> necessary they really are? When I had the machine shop overhaul the block
> back in '97, the owner insisted that hardened seats weren't necessary if
the
> car wasn't going to be a daily driver? What you all think?
|