hot tank
oil plugs

Block Tanked (15 Nov 2010)

Back from another deployment and picking up where I left off! After removing the crank and the jackshaft I took the block to a machine shop that still 'hot tanks' blocks...due to strict environmental rules many have moved to blasting verses using chemical tanks. If you do tank the block the jackshaft bearings will be ruined in the cleaning process (replacements are available from our vendors).


Oil passages (15 Nov 2010)

The top arrow is the main oil gallery...there is a plug on the front and back of the block. These are metal 'slugs' and should be removed to ensure this critical passage is clear of sludge and debris. The lower arrow is the lower tensioner oil passage...there is a restrictor installed at this location. I had the machine shop tap my main oil gallery for threaded plugs.

cleaning passages
Oil Plugs (15 Nov 2010)

These are the oil gallery plugs I mentioned in the previous photo. They measure just over a half inch. Notice the original has a hole as I drilled one thru and used a long rod to knock the opposite end out...I simply flipped the block and knocked out the drilled slug. My neighbor (gunsmith) who owns his own lathe quickly turned two new plugs, but I actually went with the two threaded plugs after having the block tapped.


Final cleaning (16 Nov 2010)

My final step before assembly was to do one more cleaning of all passages to remove any dirt or residue left from the machine shop work. A few brushes and some light soap...avoid chemicals that could ruin the already installed bearings.

ready for paint
freeze plug install

Ready for paint (17 Nov 2010)

After drying the block completely I put tape over all threads and passages and did a final wipe with Marine Clean to remove any oils and contaminants from my tape job.


Soft Plug Install (18 Nov 2010)

I painted the block red (not the correct Datsun color...see vendors for the correct blue/green block paint). I chose red because it's what I car will be a 67.5 2000 clone, so it's already "wrong", but I hope the red will look good against the black engine bay. I installed the freeze plugs after I painted...use a large socket and tap the plugs in square and flush to the block.

block painted
mid bearing

Block Ready (21 Nov 2010)

After putting a final coat on the block I gave it a few days to cure...unfortunately my water passages are starting to flash rust and I don't want to spray any other chemicals into the block...I guess I will be doing a radiator flush after I run it on the test stand.


Jackshaft Bearing (21 Nov 2010)

This is a quick shot of the middle jackshaft bearing. The bearings are available as one piece or 'split bearings' from our vendors. The front and middle have one hole that will match up with the oil passage. The rear bearing MUST have three holes match up...see next photo.

clear passages
rear jack bearing

Last Blast for the Passages (21 Nov 2010)

Today I start putting components back in the block...prior to starting I gave all the passages one more quick cleaning. This also has a clear view of how the jackshaft bearings align with the holes in the block.


Rear Jackshaft Bearing (21 Nov 2010)

The rear jackshaft bearing MUST have all three holes (pipe cleaners) in the bearing lined up in the block, the top hole is the only passage that allows oil to get up to the valve train thru a channel on the jackshaft. Notice there is a rear brass freeze plug, and a large plug fills the gap between the rear bearing and the back of the block. (the plug on the left is the new threaded main oil gallery plug).

rear main seal
cut rear main

Rear Main Seal (22 Nov 2010)

The Roadsters rear main seal is a two piece 'rope' seal. The pieces come with plenty of extra length. The seal goes in the outside can use a large socket to press it into place or the crank itself can be used to press the seal in.


Rear Main Seal Cut (22 Nov 2010)

After the seal is seated you must trim the excess...this step can be the difference between a good sealed rear main or an oil leak. The pieces need to be cut close to the block yet a small amount should be above the block about 1/8 of an inch (see photo). Not too short or too long. As Scott Sheeler says in his Roadster book "Like Baby Bear said, 'Just Right'!"

main bearings
rear main sides

Main Bearings (22 Nov 2010)

I pre lubed all main bearings and installed the crankshaft.


Rear Cap Seals (22 Nov 2010)

After loosely installing the crank give it a few taps on both ends to center the thrust bearing and then torque to a final 65ft lbs in three increments. After the caps are tight you must install the side rear main seals. Simply rub some oil on them and slide them (lightly tap) into their slots (they should install flush). Give the crank a few turns to ensure all is well (I used some old flywheel bolts offset and a breaker bar)

oil restrictor
old vs new

Oil Restrictor (23 Nov 2010)

Before I continue today I installed the small threaded oil restrictor for the lower chain's a small hole, but the restrictor is even smaller...don't forget this piece!


Rod Bearings (23 Nov 2010)

My old bearings were pretty worn (bottom), the top bearing is the replacement. The bearings have tabs which clearly match the same tabs in the rods.

rings on
  pistons ready

Piston Rings (23 Nov 2010)

I installed all of the rings on the four pistons.


Pistons Ready (23 Nov 2010)

After all rings were installed I prepared for the pistons installations. The rods/pistons have a forward facing side (there is an 'f' by the oil hole). My rods and caps are also numbered, so I layed everything out as it would be installed.

ring gap
bolts covered

Ring Gap Offset (23 Nov 2010)

Before compressing the rings I offset the rings 180 degrees out from the previous ring.


Rod Bolts (23 Nov 2010)

Before installing the pistons I covered all of the rod bolts to avoid contacting/scratching the crank journals.

compress rings
piston in

Piston In! (23 Nov 2010)

Installing the first piston...I simply rotated the crank to put that journal at the bottom of its stroke. I slid the piston down, removed my rod bolt protectors, pulled the piston into place, pre-lubed the bearing, and installed the cap. Next I torqued in three steps to 20, 40, and final to 65ft lbs.


Final Piston (23 Nov 2010)

#4 going in...notice 2 & 3 are at the top of their stroke while #1 and of course #4 are at their bottom.

pushing piston in

Pushing Piston In (23 Nov 2010)

After getting the pistons past their rings you need to push the piston down to it's crank journal. Normally you can oil the rings and they will slide easier, but I used new chrome rings and they need to 'seat' before they are oiled.


Jackshaft In (29 Nov 2010)

Moving on, I flipped the block over and installed the jackshaft. I simply lubed the jackshaft bearings and a coat on the jackshaft journals and carefully slid it in...the only caution is not installing it too far back as the rear only has a's the locating plate at the front that holds it in place.

locating plate
evil l

Jackshaft Plate (29 Nov 2010)

Well the jackshaft locating plate was not hard to put on, but as you can see from previous photo I had installed the keys in the keyway and the locating plate wouldn't slide over, so I knocked them out and installed the plate, then reinstalled the keys. I also bought a new tool as I've never owned a screwdriver that was a torque wrench, but low and behold they have them...torque the two screws to 4 ft lbs.


The "Evil L" (29 Nov 2010)

Probably the most famous engine component of the U20 is the Evil L. It's actually the upper chain guide and the top has a small bracket (L from a side view) designed to hold the cam chain sprocket in place while the head is removed...problem is the chain tensioner is driven by oil pressure, so if the chain has slack or the timing components are worn the chain rubs on the Evil L (very noticeable at start up). One solution is to cut the evil l off or best solution...fix the cause of the slack chain.

removeable L
rear jack gear

My Evil L (29 Nov 2010)

My solution was discussed on one of the Roadster forums. I took my new Upper chain guide purchased for the rebuild and pieces I cut off of the old chain guide (which was worn and no good anyway) and made mine removable.


Rear Jackshaft Gear (29 Nov 2010)

Moving along...I installed the lower chain guide (many leave this off, but I paid for a new one, so on it goes!), then I put the upper chain on the Cam sprocket and the rear jackshaft sprocket. I purchased new chains, but they were not Nissan chains so I had to mark two links with paint by counting 38 chain links between them. Simply align the shiny (marked) links with the dimples in the sprockets. The Cam sprocket should install at approx 3 O'clock and the lower sprocket will be at 5 O'clock as seen in photo.

upper chain
lower chain

3 O'Clock (29 Nov 2010)

This is the Cam sprocket at the 3 O'clock as discussed in the previos these two positions the upper chain is is it's "assembly" position.


Lower Chain (29 Nov 2010)

Same problem with my new lower chain (no shiny links) I counted 16 1/2 links and painted dots. I can't even describe all of the steps to this (buy Scott's book and you can't fail), but after installing the sprockets you can check them by aligning the two timing dimples and the rear jackshaft sprocket will be back at 5 O'clock...all of the marks should form a straight line.

lower tensioner

Chains complete (29 Nov 2010)

I've checked and rechecked and the chains seem to be aligned correctly, all marks line up at TDC and in the 'Checking' position.


Lower Chain Tensioner (29 Nov 2010)

I installed a new lower tensioner...a Roadster member (see Gordon's Garage) described an easy way to install the tensioners...simply zip tie them in the compressed position, install, and then cut the zip tie.