Ian,
I'm new to the list also, and not a previous Datsun guy, but
have built several engines. I think the first question is, how
much money/time do you want to spend. If it was running
OK before it sucked the air filter nut into its innards, it will probably
run fine afterwards if you just fix that problem. Did the nut get
caught in the valve and chip or dent the valve seat? If you
get into one valve seat, might as well check them all.
If more than a little lapping needs to be done, best to let
the head go to a good machine shop. Summers coming,
so you got to think of the driving the car angle....
If on the other hand you have large amounts of time and
money, by all means its good advice to check everything
and rebuild/replace what's needed. Got some good home
garage tips for doing it yourself, if you go there, for example
the piston bores will almost always look good, but you need
to measure them to see what's what. Best way, without
machine equipment, is to put a new ring (for your bore or
overbore) in the cylinder, seat it square with a piston, and
measure the end gap with a simple feeler gage. If its much
fatter than allowed by specs, you need to bore to next size.
If its in spec, but your used rings got too much gap, you
can re-use the pistons with new rings, as long as edge play
is not too wide. Remember to use a ridge reamer to smooth
the ridge at the top of the cylinder, if there is one, or you
will maybe break the piston rings getting the piston out.
Also, keep everything clean, like an operating table, and
write down how it came apart. I strongly advise keeping
the pressure washer away, use that only for assembled stuff.
Use solvent and wire brush, etc., to clean, and mask well before
painting. Use plasti-gage for the bearings. If the rod bearings
are OK, the mains are almost for sure OK. Check the rod
bearings first. Don't just replace the bearings, a good broken
in bearing, with good clearance, will live a long time, and give
you perhaps 1 or 2 extra horsepower than a new one.
Hey hope this helps. Oh yea, roll the pushrods on a piece of
glass to make sure they aren't bent, especially the one with
the "nut problem", and make double extra sure no
collateral damage happened anywhere else because of this.
Please take all my advice with the
knowledge that I am on a limited budget, so my viewpoint is a
little skewed in that direction. I got some questions I'm asking the
list also, maybe you can help me. (See my mail under "Misc. Ramblings")
Jim
67 1600
Chesapeake Va
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