The 13B Rebuild Chronicles :: Chapter 6 :: Longblock Assembly

1 03 2009

We now start our journey into terra incognita. Of the two rebuild DVDs I have, one (Atkins Rotary) ends after the shortblock assembly while the other (Bruce Turrentine) devotes a full three minutes, of a two hour DVD, to the longblock assembly.  So, from here we’re basicsally going by memory of what parts came off where, and the Haynes manually of course. However, because my engine is anything but stock, the Haynes manual is more of a general guide rather than a step by step procedural manual.

So, today we made less progress than last week, made a couple of mistakes along the way, but enjoyed it none the less…a day spent working on my racecar is never a bad day.

I hit the man cave around 10am and started the assembly of the front shaft in order to check the end play.

First I laid out all my parts, and got my laptop setup with Bruce Turrentine running.  Below is a pic of all the parts needed for this step.  I reused all originals except for the bearings, which I used new Mazda factory bearings just to be safe.


I also bought a new oil pump chain from Mazda, but decided to hold onto it for later as my existing chain is in perfect condition and already sized correctly.


First I slid the rear washer onto the shaft, then the spacer (a Y spacer in my case), the rear bearing, and the center plate. Then torqued the bolts down to 17 ft/lbs. By the way, these are the six shorter bolts of the twelve that are used for the stationary gears (the six longer bolts go on the rear stationary gear). I mention this to help anyone else that forgot to mark their bolts during disassembly as I did.


Next, I slid the front bearing onto the shaft (picture above).  Then took the front counterweight and inserted the washer into it (use a bit of petroleum jelly to make it stay in place), and slid it onto the shaft. Following that came the oil chain gear (teeth down), accessory gear (large chamfer facing down), and the front hub. I then inserted the key into the shatf and used a rubber mallet to tap it down into place through all the components on the shaft.  Using a large screwdriver between the counterweight and engine housing to stop the shaft rotating, I inserted the front eccentric shaft bolt and torqued it down to 95 ft/lbs.


Next step is to check the end play. I did not take a single photo of this step for some strange reason. Anyway, all that is done is to simply insert a screwdriver between the bottom of the front counterweight and the center plate, and lever it up. Using feeler gauges make sure that there is between 0.016″ and 0.028″. To round it up and make it simple, use a 0.015″ feeler gauge and ensure that it can slide freely between the counterweight and bearing. Then take a 0.03″ feeler gauge and make sure that it sticks (does not slide freely).

With that done, I then unbolted the front bolt and removed the front hub. I then pre-lubed the oil pump (using our assembly oil mixture), slid the chain around the oil chain gear on the shaft, and bolted the pump down onto the block (forgot to take a pic of that too due to leaving my third arm at home today).

To install the front cover, I painted the machined surface with gasket sealant, laid down the new gasket and dropped the front cover into place. I bolted it down using the original bolts, but found I had only five bolts, while six holes stared back at me. Hmm?  That would require a trip to Autozone later, but no big rush on that. However, when next I went to install the oil pressure regulator I found that I needed a 26mm socket, which I did not have.  So, to Autozone we go!


I picked up a bolt for the front cover (7 x 1.0 metric if anyone’s interested) and a 26mm socket ($7.15 for the socket, yikes!). Upon my return I was happy to note that the new bolt fit perfectly. I then put the front pulley back on and re-torqued the front eccentric shaft bolt.

The problems began, however, with the oil pressure regulator.  The socket and ratchet would not fit between the housings in order to tighten it down. In the pic above you can see the hole into which the oil pressure regulator goes: top right corner of the picture, in the grey metal end plate…see the center plate above it with the cross beam..yeah, not enough space to get the socket over the regulator.

About this time the cavalry arrived in the person of Doug K.  The one thing I love about Doug is that he is always calm and always totally confident that a solution is within reach no matter how hairy the situation. We tried different ratchets, adjustable open wrenches, and so on. Nothing would fit into that tight little space in order to tighten down the regulator. The only thing that MIGHT have a chance of success would be a 26mm closed wrench…but where in the heck would we find one of those?

So, Doug scrounges around the shop and spots a couple large open wrenches hanging off the side of [my shop partner] Ralf’s drill press. Long shot, probably not metric. One is 1 1/4″. The other looks smaller, probably 1 1/8″. Let’s look at it and check anyway.  It is smaller, what…no way…how could it be…what are the chances: 26mm!!  I grab it, use the closed end, it slides perfectly over the oil pressure regulator with room to turn, crank it down, and move on.

Next was to bolt down the oil pick-up, which was a simple two bolts that took us almost three hours to install. I won’t bore you with the gory details but suffice it to say that it involved an inaccurate torque wrench, a snapped bolt, a drill, a broken drill bit, a broken “easy out” bit, a tap set, a couple pounds of aggravation, swearing, sweat & tears thrown in for good measure. That done, we went to install the oil pan gasket and found the one in my Mazda rebuild kit was the wrong size for my “non-stock” engine. So we used a thick layer of grey RTV instead and installed my oil pan splash guard (definitely not a stock item).


Then more RTV and the oil pan went on. This is a totally candid shot…no posing here.


And two dozen bolts later…


Next, after lubricating the rear main seal with some petroleum jelly, we inserted it into the rear stationary gear and used a block of wood (wrapped in a shop towel) and a hammer to press it in until flush with the top of the gear.


The woodruff key was inserted into the groove in the eccentric shaft, and then the flywheel installed.


We let Matty do the honors by handling the flywheel nut.


We tightened down the flywheel nut, but did not torque it fully as this needs to be done when the engine is off the stand (so that the flywheel can be braced against the floor to prevent turning). Once the longblock assembly is complete, and the engine off the stand, we will apply blue locktite to the eccentric shaft threads, some gasket sealer to the flywheel nut, and torque it down to 350 ft/lbs.  For that we need a good size torque wrench with a cheater bar most likely and a big-ass socket (2 1/8″).


Lastly, we bolted on the intake manifold and water pump with pulley. Both of these took new gaskets from the rebuild kit, and gasket sealant of course.


And that pretty much wraps it up for this weekend. Not as much progress as I had hoped due to the hiccups along the way, but she is at least a number of steps closer to being on the track; and that, in the final analysis, is what counts.  Next weekend I hope to get the balance of the longblock finished (dreading having to figure out where all those vacuum lines go) and actually drop the motor into the car.  Maybe, if the racing gods are smiling, we might even be able to hit the ignition switch.

We’ll see you then,

Grant Boshoff
Thrust Motorsports




3 responses

28 04 2010
bruce turrentine

Neat job. It’s understandable to fret over the details on your first build. I spent such a short time on the long block assembly because most of the work is in the preparation and inspection phase. Didn’t read the details, but it looks like you were building a 12a, which would explain the clearance issue for getting a socket on the pressure regulator. The rotor housings are narrower, making a tight space even more so. 20-20 hind sight, installation would have been easier before the housing assembly. That video was made 10 years ago and many engine builds since have reminded me of other details I wished I had spent more time on. Grinding and fitting new side seals and replacement of bearings are the big ones. I’ve also changed over to installing the rotor housing first, then the dowel pins as a standard practice. My thoughts when making the video was that most people would be tripped up on the external support systems than the final long block assembly, so the time was shifted there.

7 05 2010

Thanks for your comments. I feel honored to have had my blog visited by a celebrity such as yourself. Your video was great (much better than the one produced by those other guys…ahem, no names mentioned). I would not have even attempted the rebuild myself but after watching your video I was confident that I could do it.

28 04 2010
bruce turrentine

Now I should have read the details. 13b, early, huh? 1 1/8 short socket and a torsion beam torque wrench will get in there to tighten the pressure regulator.

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