Dick:
Ummm. Have you had the engine overhauled before? Could the
machine shop have upgraded the valve size as part of a rebuild?
If you do some judicious reshaping of the combustion chamber in
the vicinity of the valve, then this will be good for some power. If the
chambers were left stock, then most likely power fell or stayed the
same.
Cheers,
Vance
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of Sally or Dick Taylor
Sent: November 10, 2007 1:26 PM
To: John Macartney
Cc: owenskenbrenda@bellsouth.net; 6pack@autox.team.net
Subject: Re: [6pack] Early vs Late Head
Several years ago I noted that my valves had fallen under the desired
spec, so far as stem diameter. This was on what is considered to be the
late (1973) head, with the better intake manifold. So I ordered a set of
both intake and exhaust valves, along with the new guides. Imagine my
surprise when the delivered exhaust valves were smaller than the
original ones! I confirmed that the part numbers were
the ones ordered, and sent them back, asking then for the "early",
larger ones. It appears that there was a crossover, when the later head
used the larger exhaust valves. Being the original owner of my '73, I
know that neither the head, valves or their seats had been previously
replaced or altered.
All of the Big Three parts books show that the '73 uses the smaller
valves. The '72 uses the larger ones. The build date on my car was
August, 1973.
John---Any ideas?
Dick
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