OK, so now we’ve gutted and cleaned The Beast. What’s next? Well, at this stage everything should be clean, all critical measurements should be taken, and the pistons marked with the matching cylinder number. The time has come to put it all back together. We personally found putting it back together easier than taking things apart. While taking things apart we took the time to take plenty of detailed photos so we could figure things out later when our aging memory is a little cloudy. This actually saved The Beast from catastrophic failure, but we're getting ahead of ourselves.
The very first step in reassembling the engine
is to install the piston coolers. Patience is a virtue here as well
as many other steps along the way. This looks simple and is, but
if you don’t pay attention, you could mess things up and the coolers are
deep in the bowels of the engine. Make sure the jet is pointing toward
the piston and the
locating lug is in the hole drilled for it. The bolt should be torqued
to 22 ft/lbs. Not wanting to take a chance here, and taking some
advice from Mike Kojima, we used some Loctite to make sure those bolts
were going nowhere once torqued to spec. We used Loctite blue since
we were just being extra cautious here and we wanted to be able to remove
the bolts at some point if we ever needed to. Be sure to put the
Loctite on the threads in the block and not on the bolts. Place the
Loctite deep enough in the threads so that it cannot ooze up to the hole
in the bolt. If you get Loctite in the hole, you will have wasted
your money on the piston coolers since you could clog them up. This
is where the patience comes in. It’s not hard, but easy to mess up.
The next step in the process is to install the
bearings in the crankshaft bores. The bearings are 2 piece.
One piece is placed in the block and the other is placed in the cap.
Pay attention to the little tabs on the bearings. They are there
to prevent the bearing from spinning in the bore. You should only
be able to insert them one way, but pay attention anyway. When you
have the bearing halves in place, coat the ones in the block generously
with assembly lube. At this time you should also install the two
thrust bearings that locate the crankshaft along the main axis of the crank.
Then place the crank in the bearings. Generously coat the journals
with assembly lube and carefully turn the crank one or two times.
This will help the crankshaft settle into the proper position. Coat
the bearings in the caps generously (note the theme here yet?) with assembly
lube and place the caps over the appropriate journals. Install the
crankshaft girdle over the main caps. Very carefully tighten the
main cap bolts in the proper order (you had better not be without an FSM
at this point) and torque to spec. Carefully turn the crankshaft
by hand a couple of times. Make sure it will turn freely. Don’t
worry if it takes some effort to get it started. Once it is turning
though, it should turn without any binding.
Before we can install the connecting rods, we have to install the pistons on the rods. This is the part that can annoy the women of the house. You’ve been warned. Turn the oven on to about 175 degrees F. Put the pistons on a baking sheet covered with aluminum foil. While you are waiting for the oven to come up to temperature, put the wrist pins in a baggie and place them in the freezer. When the oven is up to temperature, place the pistons in the oven for about 20 minutes. Prepare a workspace that you can get dirty. Personally, we used a smallish piece of plywood. When the pistons have baked for 20 minutes, remove one from the oven and one wrist pin from the freezer. Coat the wrist pin generously with assembly lube and also coat the bushing in the small end of the rod. Place the small end of the rod in position in the piston and slide the wrist pin through. You have to work somewhat quickly here because the parts will quickly come towards room temperature. There are special tools made for removing and inserting wrist pins. They can come in handy here. If you don’t use a special tool (we didn’t), be careful inserting the wrist pin. You should be able to push the wrist pin through the bore without resorting to a hammer. Have patience because this can take a few tries to get it right. We did have to use a hammer and a 3/8” socket extension to lightly maneuver the wrist pin into its proper place. Remember, we are only talking about a little positioning, not inserting. Insert the circlips in the pin bores. They are there to keep the wrist pins in place. Repeat for the other 3 pistons. We recommend you use some leather gloves for this. While the pistons will not burn you immediately, they can do so pretty quickly. Also, make sure there are no holes in the glove. You can get burned pretty quickly if they do. Don’t ask us how we know. Lastly, don’t tolerate any discomfort from heat. Discomfort can turn to a burn very rapidly. Put the piston and rod down for a couple of seconds and let the heat dissipate from your glove if you experience discomfort.
Now that we have the pistons attached to the rods, we can insert the pistons in the block and attach the rods to the crankshaft. When we wrapped up last time, we left the cylinder bores coated with STP. Now we have to clean the STP out before inserting the pistons. Once again, use Berryman’s carb cleaner to clean the bores. When you have the bores spotlessly clean, wipe them down with a generous amount of assembly lube.
Before placing the rings in the grooves, you should
check the ring gap. The FSM is pretty straightforward in its instructions.
Basically, you place the rings carefully in the bores and press them down
the bore using the piston
upside down. Make sure you insert the rings far enough. When
you have done this, you should place the rings in the grooves in the pistons.
Pay very close attention here. Many rings should only have a certain
side up. Read your FSM. The Nissan rings that have a right
side up are marked as such. Also pay attention to the placement of
the gaps. The gaps are staggered for a reason. One last point
about the rings - be careful inserting them. They are somewhat fragile
and can easily be broken. We found this out the hard way. Fortunately,
since we were using stock 300ZX rings we had 6 instead of 4 to work with.
We are almost ready to insert the pistons.
Before doing so, place the correct bearing in the two halves of the rod.
Generously coat the bearings with assembly lube. Now you should wrap
the rings and the top portion of the piston with a ring compressor.
You want to wrap the rings tight enough so they slip into the cylinder
bores. 
You
have to be careful not to over tighten the ring compressor though because
you need the pistons to be able to slip out without too much pressure.
It can take a while to get the hang of. Insert the piston skirt into
the bore making sure the piston is aligned correctly. Now you must
push the piston into the bore. This takes some effort, but you want
to be careful not to use too much. We used a hammer to insert the
pistons. No, we didn’t use the big end. We used the rubber-coated
handle. It was a great tool for this. The rubber protected
the piston top and the head and claw made a nice handle for leverage.
Once the piston is in, slide it carefully down the bore and set the bearing
on the crankshaft pin (the “shaft” that the big end of the rod is attached
to). Making sure you align the cap properly, bolt the rod cap to
the rod. Repeat with the other piston that is on the down stroke
(the ends are done together and the middle are done together). Turn
the engine upside down and torque the bolts as specified in the FSM.
When you have bolted all connecting rods to the pins, turn the crankshaft
and make sure nothing is binding. It will be very hard to turn.
You’ll probably just have to push on the crankshaft counterweights.
Just make sure everything moves.
Next on the hit parade is the timing chain. Rotate the crankshaft until the #1 piston is at top dead center (TDC). Turn the engine upside down and install the sprocket on the crankshaft. Find the correct link on the chain to match up with the mark on the sprocket and hang the chain from the sprocket. While the chain is hanging from the sprocket (engine still upside down), install the chain guides. When the chain guides are installed, tie wrap the chain to the guides so that the chain does not slip off the bottom sprocket when the engine is
turned right side up. Make sure the chain oiler is in place.
Now you can reassemble your oil pump and install the front cover.
Don’t forget to install the new front main seal before you install the
front cover. You should also install a new rear main seal and the
rear cover using gray RTV to seal the plate. To seal the front cover,
use a bead of RTV as described in the FSM. Generally speaking, Nissan
uses gray RTV for creating seals around oil and blue around water.
Nissan does use black for the thermostat and water inlet, but we're getting
ahead of ourselves now.
OK, now we are getting somewhere. Now that
the front cover is on, you can attach the upper oil pan, again sealing
with RTV gray. Install the oil strainer and the baffle plate and
then the lower oil pan, again sealing with RTV gray.
We’ve now built the bottom end of our engine. It’s time to install the head. First make sure that the locating pins are in place on the deck of the engine. We forgot them and installed the head. Later that night, while looking through our reference photos, we saw them but didn’t know what they were. A couple of panicked phone calls later and our worst fears were confirmed. We had to remove the head and buy another head gasket. Fifty dollars shot to hell, not to mention our time.
OK, we’ve got the locating pins in place.
Place the head gasket on the deck. It’s now time to lower the head
onto the block assuming you have the valves, springs, and retainers installed
already. Make sure the tie wraps 
around
the chain are near the top of the guides. This will make it infinitely
easier to remove them later since there is little room to work in that
area once the head is in place. With the head in place and the chain
free and clear through the top of the head, we can now bolt it down.
The head bolts are meant to stretch when torqued. You can measure
the bolt length and compare them with the spec in the FSM to determine
if they are suitable for reuse. We do not recommend this. In
this case, we are building a high compression engine. If you are
building a turbocharged engine, it’s even more important. Our philosophy
is that if you’ve invested the time and money to gut the engine and rebuild
it, this is no place to skimp. Buy new head bolts. It doesn’t
matter how old the bolts are. They don’t stretch with use.
They stretch while initially being torqued. The process for torquing
the head bolts is unusual. You must torque each bolt in the proper
sequence to 28 ft/lbs. Then go back and torque each bolt in the proper
sequence to 56 ft/lbs. Now fully loosen each bolt in the proper sequence.
Go back and torque each bolt in the proper sequence to 28 ft/lbs (sound
like a government job?). Now, what you must do is turn each bolt
90 degrees, again in the proper sequence. Now go back and turn each
bolt 90 degrees again – of course in the proper sequence. Be careful
here. Do this slowly and methodically. Remember that you are
screwing steel into aluminum. The threads in the block are deep,
so helicoiling the block would not be an easy task. It’s a little
intimidating because of this. Our 18” long, ½” drive breaker
bar was actually deflecting a few degrees during the final torquing sequence!
Now that the head is in place, we can finish assembling the head. We cannot do this while the head is off the block because the head bolts are underneath the cams. The first step is to fill and bleed the hydraulic valve lash adjusters (HVLAs). Get a container that will hold one quart and fill it with fresh motor oil. Place the HVLAs in the container standing straight up as shown in the FSM. You may see some bubbles come out of the top. To bleed the HVLAs, we need a small metal shaft to insert into the top of the HVLAs. We used a small Allen wrench. With the HVLAs still underneath the oil bath, insert the shaft into the HVLA and press down. You will see bubbles rise. This is the HVLA bleeding and filling with oil. As each HVLA is bled, we insert it into an appropriate bore in the cylinder head. After inserting the HVLA, place a pair of matching shim and rocker guide on the top of the corresponding valves. Pay attention to which one goes where. Failure to do so could lead to a major failure. You must also make sure your pair is indeed matched. If you disassemble your cylinder head yourself, segregate each pair and mark them. A really good shop will machine the ends of each valve stem to exactly the same height after installation. This is what Dan Paramoure Racing (DPR) does. In this case, you must measure the thickness of all your shims and guides and match them up to within 1/100th of an inch. If you don’t have the valve stems ground to the exact same heights, or match the guides and shims upon removal, the process of installing the shims and guides and matching them properly is rather involved and requires special tools. If you have any new valves installed and the shop does not machine the ends of each stem to the same height, you are stuck with using this process.
Now that we have the shims, guides, and rockers in place, it is time to install the cams. Carefully place a cam in its proper bore. Generously coat the machined surfaces of the cam with assembly lube. Then place the correct caps over the cams along with the correct bolts. The FSM specifies which caps and which bolts go where. We used great caution while tightening the bolts. It is very easy to break the cams during this process. Remember that as the cams are being tightened in place, they must also compress some valve springs. It is very important to tighten each bolt in sequence and by equal amounts. This will keep the stress along the cam even. Repeat with the second cam. Once the cams are in place, it is time to both install the cam gears and set the cam timing. There are marks on each cam gear that must be aligned with the proper link on the timing chain. It helps greatly to have at least one helper for this.
Before installing the gears, we must snip the tie wraps that hold the chain to the guides. It is extremely important that tension be maintained from this step until the cam gears are installed. This is to ensure that the chain does not slip off the sprocket on the crankshaft, possibly altering the cam timing. It is also extremely important that the tie wrap not slip down into the front cover. If this happens, the cams, cylinder head, both oil pans, and the front cover must be removed and this process started all over again.
During this process, the person assisting should hold the chain up while the tie wraps are snipped. After they are snipped, the cam gears should be tie wrapped to the chain with the marks on the gears matched to the corresponding links in the chain. At this point, it is almost certain that the gears are not lined up properly with the cams. That’s OK. Using a large adjustable wrench (ours didn’t fit) or a 24mm (stock) or 25mm (JWT) open wrench on the flats of the cam (near where the gears bolt in place) we can turn one of the cams until the pin on the cam lines up with the keyway on the gear. Now we bolt the gear on and repeat with the other cam. Now, while we’re holding the cam with the open-end wrench we torque the bolts down. It is important to be very careful while turning the cams with the wrench.
At this point the long block is complete. The valve cover, intake manifold, power steering pump, oil pressure sender, various emissions components, and auxiliary parts are bolted in place using the instructions in the FSM. It is important to use new gaskets for the fuel rail if it has been removed from the intake manifold. Use new o-rings with the injectors if they were removed from the fuel rail. Ours were removed since we installed 370cc injectors, so of course we used new gaskets and o-rings. While installing the injectors in the fuel rail, it’s important to be very careful. The injectors will not press all the way into the fuel rail by hand. Screwing down the aluminum caps that are on the top of the injectors presses them in. It is important to keep even pressure on both sides of the caps while screwing them down. Do this in slow steps. We broke three of the caps on our G20 while screwing the caps down.
Hook up all vacuum and water lines and replace
any lines that are questionable. We had to replace a water hose that
is hidden under the intake manifold after we installed the engine in the
car because the hose went bad. When plans call for a header
on the engine, it is probably best to wait until the engine is installed
in the car before installing the primaries so they don’t get bent during
the installation process.
Check back soon for the next installment.
Copyright George D. Roffe 1999