How to Prime that Datsun Roadster (R16/U20) Engine!
by Thomas Walter c 1998
After a fresh engine has been built, or after the engine has been
sitting for a period of time (a month, for my roadsters), it is
advisable to circulate oil through the engine prior to cranking it
over. This is especially true of Over Head Cam (OHC) 2000's engines.
For the 1600 & 2000's, and oil pump priming rod can be made from
a 0.5" aluminum rod about 8 inches overall length. One end is turned
down to fit into a 3/8" electric drill, the other end is cut into a
tang about 0.180" wide by 0.400" deep to engage the oil pump shaft.
Disconnect the small electrical wire to the distributor.
Pull the distributor, leaving the cap and wires attached and in
the engine compartment. Make a note of where the rotor is pointing!
[You'll need to confirm that is back to the same location, when you
are done.]
Now remove the tachometer drive cable, and the small oil line to
the tachometer drive housing. A flare nut wrench is best to loosen
the oil line fitting.
Remove the two bolts at the base, and lift of the tachometer drive
housing.
The drive gear is sitting in the engine. Make a note of its position,
before removing it. Remove it with a pair of needle nose pliers,
and observe the gear as it will rotate slightly to the right. Once
removed, add a third note to your page on the orientation of the gear,
as it clears the jackshaft gear. When you reassemble, it will be much
easier to hold it in the same position, and let it rotate back into place.
[This may sound odd until you have done it, but the idea is to make
reassemble as easy as possible!].
Now use a 3/8" reversible drill, fit the oil pump primer rod, and
slide into place so the tang is engaged on the drive pump. I prefer
an adjustable speed drill, and will *reverse* spin the oil pump to
build up pressure.
Since the aluminum rod will be running against the steel... You should
"lubricate" the oil pump end with a little engine assembly lube PRIOR
to use. This prevents the softer aluminum from leaving particles of
aluminum behind as the rod spins against the harder ferrous material
Remember the line that goes to the tachometer drive housing? You'll
notice it is connected off the main pressure galley, and will suddenly
be squirting oil out before you realize it! I just lean it back over
the open hole, and let it lubricate the oil pump priming rod!
With the oil fill cap off you should see oil rushing out of the camshaft
lubrication hole (U-20 Only). Let it run for a minute after that, to
confirm the engine has been fully oiled.
After having the engine primed with oil, reassemble everything in reverse
order. Check with you notes to make sure the distributor drive gear, and
rotor, all end back up in the same position. Once everything is rechecked,
and the car warmed up I'd recheck the ignition timing.
Usually the above procedure takes less than 15 minutes total. Give your
self an hour the first time, as the gear will occasionally slide back in
the wrong way. With a 14 tooth gear, if reinstalled off... the will be off
by 25 degrees... which is noticeable, if you made detailed notes.
If the oil pump drive gear does not sit down flush into the block,
most likely the tang did not match up with the oil pump. Pull the
drive gear back out, and move the pump tang slightly with a flat
bladed screwdriver and try again. Do not attempt to "Force it"
by bolting up the tachometer drive housing in place, or you may
break the ears of the housing.
NOTE: At one time I had these rods made up, and sold them via
mail order. Currently the only time I sell the remaining stock
is at a Datsun Roadster Meet such as the Mt. Shasta (held the
second weekend in July) event in Northern California. -- TW
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