One immediate thing that comes to mind when you run tighter clearances is
that you run the risk of burning one or more valves. With a tighter
clearance, the valve opens sooner and closes later, effectively reducing the
amount of time that the valve has a chance to cool (while some cooling
occurs thru the valve guide, the valve cools best when fully closed against
the seat). Exhaust valves are more prone to burning as they are exposed to
the hot exhaust gases, while the intake is afforded the cooler intake
mixture.
I'd be the first to admit I'm no expert when it comes to valve/cam timing,
but if I remember correctly running tighter clearance will advance the cam
timing. Perhaps the more knowledgeable can continue this discussion,
Barney...
Jeff
'70MGB
Valves:"Rather hear them than smell them..."
----- Original Message -----
From: "Rich & Kerry Peterson" <kerry3@earthlink.net>
To: "MGS" <mgs@autox.team.net>
Sent: Sunday, July 22, 2001 10:47 AM
Subject: Valve Noise Revisited
> I've been following the thread about valve noise with some interest as I
> recently concluded that my 77B with 115,000 was a tad too noisy. The
valves
> are adjusted correctly (although I will have to check for rocker wear as
per
> previous emails) and still they clatter. My question is this: what is
the
> reason for such a large clearance and what would happen if I adjusted them
to
> 0.007" or 0.008"? It seems to me that the added duration that the valves
> would be open wouldn't be a problem and the additional lift height
shouldn't
> cause any interference . . . any thoughts?
>
> Rich P.
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