Hi Peter,
I have a few questions for you in private regards the head, it may have
bounced around to a few individuals.
Aside from that, the cam towers will need to be aligned for the cam,
regardless of whether they are from another head or that one. If you
don't, you run the risk of the camshaft binding and possibly snapping,
with disastrous results. If you don't have a mechanic available, you can
do the alignment yourself, by temporarily mounting the head to the
engine block.
Loosely mount the cam towers. Use some blueing ink on the bearing
surfaces of the towers, and mount the camshaft. Turn the camshaft
occasionally by hand, while you tighten up the cam towers equally, and
to the point where the camshaft still spins by hand. Keep in mind that
at this time you are not installing the chain sprocket gear, or any
valve connectivity to the camshaft. Just the camshaft by itself so it
will spin freely independent of the rest of the engine. (And it does
make a difference being mounted to the engine versus on a table-top.)
Then remove the tower caps, and observe where the wearing off of the
blueing ink is. That will show you the spots that need to be machined.
You can do that yourself with an appropriate tool (for me, that's a drum
with crocus/emery cloth). Don't take off too much at a time, and
regularly re-insert the camshaft and test-spin it by hand until there's
relatively no friction or binding.
I did this on my last U20 rebuild and everything worked great. Only
difference is, I was done with the head and permanently installed it
before doing the alignment of the cam towers. You might want to research
whether you need some shims on the towers to make up for the lost
90-thousandths. Just to make the geometry right (I would).
Fred - So.SF
-----Original Message-----
From: owner-datsun-roadsters@autox.team.net
[mailto:owner-datsun-roadsters@autox.team.net] On Behalf Of PETER
VANDERPAS
Sent: Friday, June 10, 2005 6:35 PM
To: datsun-roadsters@autox.team.net
Subject: How do I check a head?
I purchased a bare head for a '68 2000 on eBay and I
would like to know how to go about checking it out.
The seller sold his roadster somne time ago and was
cleaning out some extra parts he had left over. He
states that the seats are surfaced and the guides
knurled. No cracks or welding done. It has been in
storage since 1980. It was surfaced about 90
thousands.
Are there measurements I can take to make sure it has
not been cut beyond specification? Anything else to
look for? Also, I would have to use the cam towers
from the existing head. Do these just bolt up, or is
there additional machining that needs to be done to
make them work?
|