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Thursday, April 6, 2017

Triumph Spitfire Engine Rebuild #16 - Crankshaft Installation

Finally! The GoPro video thing is just not working out for me the way I planned, so I'm skipping that for now. Maybe in the future I'll get some stuff posted. Though I didn't take as many pictures as I should have, especially at the beginning of assembly, I'll do my best with "regular" posts.

Where I'm at, give or take.

Where I started. Made some progress, I'd say.

The crankshaft has been in and out of the motor a few times and I documented crankshaft installation previously here. There really isn't much more to say on the subject except that I did polish the journals of the crankshaft a bit.

The method I used involved using a strip of 220-grit wet/dry sandpaper trapped between the journal and a shoelace. I used WD-40 as a lubricant.

Like starting a camp fire.

Then I just pulled the two ends of the shoelace, alternating, so the sandpaper would "spin" around the journal. I did this about 20-30 times, then rotated the crankshaft 90-degrees and repeated the 20-30 times until I got all the way around. Unfortunately, I couldn't get really good before/after shots because of the lighting and the glare from the journal surface, but I tried.


After the 220-grit pass.

There is some obvious difference, but it was much better in person. I repeated the same procedure, but using 400-grit, to finish up. Of note, I could not feel any grooves in the journal before I did this. Along with the good measurements that I got, I decided to not get the crankshaft professionally worked. If I found any grooving of the journal surface, or the measurements were bad, I would have taking it to the machine shop along with my other stuff.

I lubricated and installed the main bearings (meticulously clean!!!), set the crankshaft in, place the bearing caps in their correct orientation, and torqued it all down.

ID mark on the block for bearing cap orientation.

ID mark on bearing cape. The first punch didn't work out as well, I guess.

The main bearing caps get torqued to 55-60 ft-lbs. My method of torquing this (and all other items), which is the guidance provided by Naval Ships Technical Manual 075, Fasteners, is to bring all of the bolts to about 10% of the specification to ensure proper mating of the surfaces. Then, in 25% increments, bring all of the bolts to the torque specification. For these bolts and other areas where even application is important to prevent warping (like the head), I am concerned with relaxation. To combat this, I paused at about 75% torque and waited about an hour to allow the torsional stresses to relieve, then brought all of the bolts up to the final 55-60 ft-lbs.

Along with the main bearings, I installed new, full-alloy thrust washers from Custom Thrust Washers, which I also mentioned in this post. After everything was torqued, I measured the end float, which came out fine.

Thrust washers that came out. I know I took pics of the new ones, but darn if I can find them! They're the same, but much prettier.

The thrust washers fit in those grooves between the bearing housing of the block and the crankshaft.

Once that was done, the front sealing block was installed. Made of aluminum, these are easily damaged by over-tightening of the oil pan or front plate bolts. Mine seemed in good shape, however, so I got lucky.

Another quirk is that there are two small pieces of wood at either end that act as a gasket between the sealing block and the motor. The sealing block is installed such that is is flush with the front of the motor and tightened down.

Checking the proper fit of the sealing block. The clear liquid is Gasgacinch.

The wood, which is cut slightly oversized, is placed in the groove between the block and the motor and then hammered down to provide a tight seal. The tops are then trimmed flush with the bottom of the motor.

Wood installed and hammered a bit. You can see the ends being shaved to fit. Custom!

Cutting the block flush. Not very elegant, but effective.

The finished product. Note the two small paper gaskets between the screw holes and the block.

Once that was done, it was on to fitting the rear oil seal. Being an earlier motor, this is a scroll type seal. Before the advent of modern polymers that could maintain a seal around a rotating shaft, scroll type seals were used. In essence, a spiral, similar to threads of a screw, are cut into both the crankshaft end and the oil seal assembly.

The scroll cut into the rear of the crankshaft.

The scrolls are cut such that, with the rotation of the crankshaft, the oil that tries to flow out will be drawn back into the crankcase, almost like threading a nut onto a bolt. Oil leaks are not unusual with this type of seal, as far as I can tell, but they are effective enough.

The oil seal assembly is put on the back of the crankcase and snugged down with the seven bolts. Then, a feeler gauge is run around the circumference of the crankshaft. The clearance should be about 0.002" between the crankshaft and the oil seal assembly. I used a mallet to lightly knock the oil seal into place as necessary. While not perfect, I got very close to 0.002" all around.

Oil seal installed.

I'll end it there. As you can imagine from the first picture, I have a lot to catch up on. Piston installation will be next.

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