1939 Wraith Engine Overhaul
Detroit, Michigan

Part III - More Assembly


January 1, 2008

Since the poundage test was successful, the damper has been disassembled and cleaned. Here is the rear half of the unit with the first Fiennes friction disc installed.

The intermediate plate is in place with half of the springs installed.

There are smaller diameter springs inside the large springs which are captured by a nub in each spring pocket.

Notice the 1BA socket wedged in there to create enough space to get the second half of the springs installed.

Second Fiennes friction disc.
Pressure plate. This portion of the assembly is attached to the crankshaft and then the remainder is assembled afterwards.

Since that will be a few weeks, the rest of the unit has been temporarily fastened in place to keep dust and dirt out.

John from University Motors contacted me a few days ago: Casey the machinist will begin the line boring job on January 15th when he (Casey) gets back from Guatemala.

January 6, 2008

In order to prepare the rocker cover for repainting, two placards need to be removed. Removal is necessarily delicate - it's not like there's a stash of N.O.S. placards laying around somewhere.

This one was held in place with #2 drive screws which can be tapped out with a small nail set from the other side.

The other one was riveted. For that, the rivet heads were ground off and the rivets were tapped out from the outside.

Any remaining paint has been stripped chemically, wiped with lacquer thinner. Then, the entire part was washed and dried, ...
primed, ...

...and painted.

Since I need to order new spiral drive screws from Restoration Supply Company, I will also attempt to get the correct spark plug connector for the new ignition harness I plan to make.

In the owners handbook, the originals looked like a forked connector held on the spark plug insulator with a knurled brass nut.

January 21, 2007

Not much happening on the Wraith front, I've been working hard on creating an entirely new website for the Motor Region of the Rolls-Royce Owners' Club.

Since I'm still waiting on the crankcase, the water pump seems like a good mini project.

Originally, I was planning on letting well enough alone. Upon further investigation, however, the end play on the pump is 0.040 inches. It's supposed to be 0.005. It would seem then, that a rebuild is in order.

You may recall from a few pages back that this unit is shaft-driven from the back of the generator.


All of the peripheral items are easy enough to remove. The aluminum case itself is cast in two halves and held together with four 2BA nuts, a gasket and 70 years worth of corrosion.

Repeated daily applications of penetrating oil will be a necessity.

January 23, 2007

The water pump has lived a good life. With only one day of soaking with PB Blaster, the two halves of the casing came apart with minimal prying and no heat.

The inside is very clean with little or no pitting.

With the spring coupling removed from the splined end of the shaft, the impeller and shaft come out readily.

Once the threaded water pump gland nut (upper left) is removed from the nose, almost all of the sundry bushings, spacers, springs and packing material can be removed.

The shaft appears to be scored somewhat. I will have to consult "the elders" to determine how much wear is too much. Fiennes sells stainless steel replacements for £32, so it's not a matter of life and death.

This is the thrust pad on which limits the rearward movement of the shaft. It looks pretty thick, so I am wondering if all the wear has occured on the thrust collar which is shown two photos down.

This looks to be a natural material. Although I've been told the older small HP Rolls-Royce use lignum vitae, a type of very dense wood, I thought these were supposed to be brass.

This inner bush, which is made from lead, was destroyed during removal. It is a wear item, so the plan was to replace it anyway. The replacement is made from marine grade plastic.

This thrust collar is the last piece to be removed. The replacement is also made from marine grade of plastic.

I must mention that Gary Phipps wrote a wonderful article on Wraith and Phantom III water pumps for the Phantom III Technical Society. Without that as a reference, this would have been a much more frightening experience, especially when you take into account replacement water pumps change hands for about $2000. If you have a Wraith or Phantom III, you should join! www.p3ts.org

January 27, 2008

Over the last few days, I tried various means to coerce the thrust collar out to no avail. Today, I drove up to Bob the Machinist's place where he chucked the pump in his lathe and turned out the collar in short order. This photo shows him setting up.

Meanwhile, Roger Townsend is sending me a NOS pump gasket and some R-C ignition terminals. Speaking of ignition, the PIII Technical Society is sending new packing material for the pump and also bakelite id collars for the ignition wires via Gary Phipps.

The small marks here and there in this photo are from my previous attempts, not Bob's.

Fiennes Restoration is sending a new inner bushing and thrust collar, along with a new set of springs for the vibration damper. I changed my mind and decided to replace them. He's also sending me a kit of Ross-Courtney terminals and some nickel-plated top nuts for the spark plugs.

After talking to Will, it turns out the thrust pad should be made from ferobestos not brass. Mine is correct and as new with 0.125 thickness.

February 2-3, 2008

The water pump castings have been chemically stripped, the stubborn areas attacked with a wire wheel on a pneumatic die grinder.

Masked areas mimic the original paint scheme.


...and painted.

Reassembly will have to wait until the inner bush and thrust collar arrive from Fiennes.

My car was built with optional heat. One of the two heater taps had a slow leak. Disassembly reveals a complete absence of a gasketing scheme in the design, it appears to rely on a close tolerance fit and surface tension of the coolant. I used lapping compound to make the fit between the valve and body as tight as possible and then greased the interface with water pump grease.

It will be a few months before I find out if the unit now water tight. Trial and error is ok, as this item is fairly easy to remove with the engine in place.

I talked to John Twist this past Wednesday. He indicated that Casey is indeed back from Guatemala and setting up the equipment to do the line boring. "Measure twice and cut once" never took on such gravity!

Hopefully I will have the crankcase and associated components back in my hands by next weekend.

February 4, 2008

The shipment from Fiennes arrived today. The new inner bushing and thrust collar are shown on the lower right.

An 18mm deep well socket comes in handy for pressing in the inner bushing.

This socket is also a perfect fit to remove and install the 7/16 BSF thrust pad screw which is about an inch high.

It's a happy accident, really, because it is one of the few Whitworth sizes that is very close to something else: a 7/16 BSF nut is 0.710 in. across the flats which happens to be 18.03 mm!

Thrust collar installed with a few light taps of a small rubber mallet.
The collar is reamed to a final i.d. of 0.4375 (7/16 in.) The brass bushings are temporarily put into place to steady the shank of a very sharp, brand new 7/16 in. bit that is turned by hand. With the bushings in place, the radial alignment of all the bushings i.d. is assured.
After clearing the plastic shavings, next comes one of the first of two sealing glands made from 1/4 inch Packmaster #6. This is followed by the intermediate pieces with spring, another sealing gland and finally the outer bushing and gland nut. The packing washer is omitted for now as this assembly is difficult to compress as it is.
The water pump is assembled the rest of the way minus gasket and any old adjustment washers behind the thrust pad. End play is 0.017 in. Since the missing gasket is 0.005 and I am shooting for 0.003-0.005, I will endeavor to find a 0.017-0.019 in. adjustment washer.

February 8, 2008

The upper crankcase has returned with a set of line bored bearings. John Twist of University Motors was kind of enough to interupt the three day seminar he was teaching on all things MG to chat about the Wraith engine.

Next thing I knew, the entire class had come over to the tables where my engine pieces were stored. We then proceeded to have a question and answer session!

Check out John's website, click here.

February 9, 2008

One of the four 2BA studs that holds the two halves of the water pump together was incorrectly replaced with a hex head screw. In order to finish up the water pump, a new stud made from 3/16" dia. 12L14 carbon steel rod is needed.

My little die holder has gone missing, so please cut me some slack.

Completed stud.

The NOS gasket does not account for the assymetrically placed hole at the top no matter which way I install it. Since the gasket had to be moistened get it to stretch slightly, the moisture will hold the orphaned piece in place until the halves are joined together.

Also, three 18-8 stainless steel 0.375 o.d. x 0.250 i.d. x 0.006 in. thick shims were added behind the thrust pad screw to achieve the desired end play.

The final product. Note that the new hose clamps are proper Jubilee clips.

The other heater tap has been cleaned and lapped in the same manner as the previous one.

I need to find a replacement for the sealing washer in the foreground. This seals the tap to the hex head extension attached to the right.

All of the oilways have been sealed with purple electrical tape in preparation for a leak check (checking for air bubbles) in a bathtub full of water.

This ensures that the sludge traps will not cause a loss of oil pressure. All but two of the 26 joints were leak free.

In both cases, the leak was at the fastener and not around the edge of the bung. Reassembling these with a bit of Loctite retaining compound should do the trick. (And yes, the crank has been thoroughly dried and sprayed with WD-40.)

February 16, 2008

The day after the crankshaft test above, I came down with the flu. As if this wasn't enough, I ended up with pneumonia as well. In bed for a week with an unbuilt engine in the basement, the best I could do was alternate between Daytona 500 Qualifying and Project Runway on the TV.

Finally feeling better, step one was to press this new pilot bearing into the flywheel. Well, I screwed up, pressed too hard and now the bearing's ruined and I can't get it back out. Off to B&F for some remedial work and a new bearing...

February 19, 2008

While I wait for the new pilot bearing, there's no reason why I can't attach the pistons to their connecting rods.

First, the pistons have to be boiled so that the gudgeon pins will come out.

Incidentally, the pistons were manufactured by JP Engineering in Australia.

Here are three of the assemblies after baking in the oven to remove any trace of water. The pistons are slotted on the "non-thrust" side.
The new connecting rods, which are from the later Bentley Mk VI, have an oil squirt hole that lubricates the thrust side of the cylinder wall. Thus, the hole side of the connecting rod is installed opposite the split side of the piston.
Snap-ring detail.

February 23, 2008

When I had previously assembled the camshaft into the crankcase, there was a slight degree of binding, presumably due to some glazing on three of the aluminum shells. (Nos. 2, 3 and 5.)

These bearings glazed because their oil feed holes were occluded with oil sludge.

This time, I lapped them just enough to remove the glaze.

Inserting the camshaft is still a painfully slow process, even the second time around.

February 24, 2008

After much tweaking, all of the cam bearings are lined up with their retaining pins inserted. The cam wheel has been installed with the new 0.0790 thick spacer and locking tab washer.

The relationship of the camshaft to the flat on the splined distributor shaft is not important because the distributor cam is adjustable 360 degrees.

Eight 1/4 BSF studs (in four different lengths) have be installed on the front face of the crankcase after thread chasing and application of anti-seize.

Nine 5/16 BSF studs (in two different lengths) have be installed on the bottom face of the upper crankcase half as well.

Pete Kohnken has volunteered to help me do the cylinder honing which will probably be Tuesday. He's waiting for a new digital bore gage to arrive.


This is the upper crankcase rear main seal carrier with a new felt seal installed. I'll trim it to length once it is installed.

In other news, I have the flywheel back with the damaged pilot bearing removed. B&F did not have a new bearing, but Bearing Services, Inc. in Livonia did. That should arrive Wednesday. Not only that, this one will be sealed (to keep out the clutch dust) and cost half the of the one I bought from Fiennes.

This is the hydraulic brake damper which is mounted to the left exterior of the lower crankcase. It appears to have a pair of pistons that run submerged in oil. There was enough oil present to prevent damage, but probably not enough to function correctly.

There is no mention of any required maintenance in the owners' handbook, but there is clearly a provision to drain and refill the unit if you look at it up close.

It has been reassembled and topped up with SAE 30 oil.

February 26, 2008

I did indeed make it to Pete Kohnken's place tonight for "honing night".

After all the hubub about getting a digital bore gauge, we measured the bores and could not get the readings to be very repeatable.

The piston measurements were made at the base of the skirt with a micrometer 90 degrees to the gudgeon pin.

Next, we used one piston to establish the relative size of all of the cylinder bores using feeler gauges.

With these clearance measurements plus the piston sizes as a guide, it became clear we had two relatively small pistons and four large. (The difference between small and large was a few thousandths.) The bores worked out the same way: two small and four large.

After some mixing and matching, the clearance of all of the pistons in their newly assigned bores worked out to 0.0029-0.0032 inches. Perfect!

Before any honing can take place, the ridges at the top of piston #2 thru #5 have to be removed. (#1 and #6 were sleeved so there is no ridge present.)
This is the ridge removal tool. It is operated by hand using a socket wrench.
Next comes honing. The metalworking fluid of choice is kerosene. An industrial bug sprayer is the perfect application tool.
Because we only want to remove the glaze and a minimum of metal, we started out with this wimpy hone.

It was too wimpy, so Pete broke out this "manly" hone. It still had a relatively fine "grit" to it, though, but it performed the job in short order.

All of the piston clearances were rechecked after this step and everything is still very much in spec. Whew!

Final operation is this plateau brush. It knocks off the rough edges of the hone pattern. The rings can still bed properly, but their longevity is enhanced.

Unfortunately, the one Pete had is suited to the 3.75 inch bore found in a Silver Cloud rather than a 3.50 inch.

I'll order the right size tomorrow and finish this up later in the week.

February 28-29, 2008

Before installing the rings on the pistons, the ring gaps have to be checked so that they can be mixed and matched to the smaller and larger bores. The gaps on the top rings should be within 0.008-0.010 and the middle rings 0.006-0.008.

A ring with a 0.008 gap in cyl. #1 has a 0.011 gap in cyl. #3 because #3 cylinder is larger by 0.0005. If you do the trigonometry, the gap should be 0.0016 larger if the diameter increases by 0.0005.

Here are the rings in neat little piles based on ring gap in cylinder #3 as measured 1.10 inches from the bottom of the bore. Cylinder #3 has one of the largest bores, the gaps will be equal or smaller in the other cylinders.

3 - 0.006
1 - 0.007
2 - 0.008
1 - 0.009
1 - 0.010
4 - 0.011

All of the 0.011 rings will be used in cylinders #1 and #6 which are the ones that are smallest because they were sleeved.

When all the mixing and matching is over, this little device can be used to safely file away small increments of the ring at a proper angle.

Good thing I borrowed the tool. I only used it on one ring!

I also used a very fine, very small flat file to slightly chamfer the edges of the ring gap that come into contact with the cylinder wall.

The oil scraper rings do not need to be sized. The ring gap can be checked with a 0.006 feeler gauge used as a go-no go. Only one of them needed adjustment.

Piston to Bore Clearance
Top Ring Gap
Middle Ring Gap

Here's the final score. Not too bad if you allow for the fact that I ordered only enough pistons and rings to do the job.

The specs in parentheses are from the Haynes & Grigsby book on Rolls-Royce Small HP Engines.

The new plateau brush came in yesterday.

Today, I succumbed to temptation and purchased a nice new 1/2 inch drill to drive the plateau brush.

In a matter of minutes, all six bores were treated to the plateau brush at 800 rpm. (In and out 10 times for each cylinder per the manufacturer's recommendation.)

Here's a piston with the rings installed. A ring pliers is needed for the top and middle ones.

Turns out I missed a fine point when installing the gudgeon pin circlips.

According to the cognoscenti, one should ensure that the "chamfered edge" of the clip is installed inward towards the pin. When I endeavored to check this today, I couldn't see a chamfered edge. I could see that the circlips are a stamped part, though, and that there is a clean edge and a ragged edge. The circlips were reinstalled with clean edge inward.

March 1, 2008

Here is a tappet slathered with assembly lube. Each of the 12 tappets was stored in separately marked bags so that they can be installed in the same location from which they came.

After cleaning, the periphery of the tappet bottoms (shown off to the right) remained discolored. (Not the bottom itself, though.)

There is no noticeable accumulation of material in this area, so I left well enough alone rather than doing anything to aggressive.

In it goes...

The distributor drive gear is coupled to the generator/water pump shaft via a small three layer "flex plate" of sorts.

Before that is installed, this stamped keeper is installed over the distributor drive nut to prevent it from rotating. This is in addition to the fact that the nut itself is left hand threaded in order to be naturally self tightening with the clockwise rotation of the gear.


March 2, 2008

I used the electric impact gun to tweak the nut the last few degrees so that the keeper holes line up.

End play verified to be spot on at 0.003 inches.
Next, the generator shaft is inserted and woodruff key installed.
The driving spider is pulled down over the top of the generator shaft. Note all of the little cotter pins installed the Rolls-Royce way.
In this wider shot you can see how the generator rests in the large boss to the right and mates to the back of the generator shaft.

March 4, 2008

The new pilot bearing arrived today. The new one's in the box and the original Hoffman bearing is shown to the right.

I forgot to take a photo of the new bearing out of the box, but it is the permanently lubricated sealed version. This is the perfect application for a sealed bearing: the clutch dust needs to stay out and there is no provision for lubrication once the bearing is installed in the flywheel.

You may recall that the old flywheel bolts were peined to their respective nuts. Removing them was a destructive process.

Fortunately, Jack Barclay's had reasonably priced NOS ones. Terry cheerfully handcarried them from London to Oregon for me so that I might collect them at the RROC National Meet last summer.

The shoulder is a slight press fit into the crankshaft flange and the top has a flat side to prevent rotation of the bolt.

Rather than peining, I used Loctite 262. This solution will offer superior holding power and allow the nuts and bolts to be reused the next time the engine is overhauled.
Here is the finished article. In case you were wondering, I did temporarily attach the back end of the clutch assembly to make sure that the TDC mark on the housing corresponded to TDC for throw #1 on the crank prior to final assembly.

March 7-10, 2008

No progress on the engine to report for this past weekend. Instead, my roommate from engineering school, Al Brightman, invited me to come down to the Amelia Island Concours d'Elegance for a large dose of sunshine and automotive enthusiasm.

This very unusual Rolls-Royce is a Phantom III. It won the People's Choice Award as well as another award for the most audacious.

Although we have been living and breathing Small HP Rolls-Royce engines for the last 10 months, we can still recognize greatness when we see it: Rolls-Royce or otherwise.

This enormous Lycoming straight 8 is a sight to behold. It does not leave much room to spare under the hood of this Duesenberg.

March 12, 2008

This is the upper crankcase with a new gasket in place.

There is an oilway near the front and back that was slightly blocked by the unstretched gasket. A little adjustment with the X-Acto knife leaves one less item to chance.

Steven and Thom, our crazy neighbors, assisted in placing the block over all of the studs onto the crankcase. It would have been easier to drop the block in place without the studs installed, but removing them after getting the lengths right and torquing them just so seemed like a bad idea.

Doing it this way, it still only took us ten minutes and then we all went out for Chinese food.

March 13, 2008

With the change to Daylight Savings Time, it's much easier to get things done during the week now that the work has moved back out to the garage.

This is the assembled crankshaft about to be gently lowered with Tom Wernholm's engine hoist onto the inverted upper crankcase.

Yes, that's snow by the Honda. But not for much longer: the temps will be in the low fifties for the next few days.

Of course, it's helpful if you remember to install the rear main seal carrier first.

The crankshaft had to come back out, then the rear main seal went in, followed by the crankshaft.

The main bearing caps have been installed. The crankshaft turns with everything finger tightened, but it's a little stiff. I think it's the rear main seal mostly as it felt fine when I installed the crankshaft without the seal.

This weekend I will support the front of the crankcase properly and finish the installation by torquing to spec and measuring with Plastigauge (for bearing clearance) and feeler gauges (for bearing nip and end float).

March 14, 2008

An excellent way to check main bearing clearance is to use Plastigauge. It's a soft thread of wax that deforms to a predictable width when crushed between the bearing and journal.

This is compared to a card supplied with the Plastigauge material to determine the clearance. When torqued to 27 lb-ft, all bearings had running clearance between 0.0020 and 0.0025. The spec is 0.0020-0.0025. 3M Adhesive and Wax Remover (03607) is a good choice to remove the Plastigauge residue.

I also checked bearing nip (or crush). My measurements were a little less reliable, but all between 0.0020 and 0.0035. The spec is 0.002 with no tolerance provided. I will trust the machinist and leave well enough alone.

March 15, 2008

I remembered to measure the crankshaft end float which is 3.5 thousandths. Rolls-Royce spec is 2.5 +/- 0.5 thousandth, but the Haynes & Grigsby book says 7.0 is the upper limit. Depending on who you listen to, I'm fine or close to fine.

This is no F1 team: I'm not going to throw away $3,400 worth of parts and labor to get that last 0.5 thousandth!

This photo shows a new pair of Crewe big end bearings from Albers test fit into a Bentley Mk VI rod from Tony Handler. So far so good.

For the first piston assembled into the engine, it seemed like a splendid idea to check the running clearance with Plastigauge.

Including the discolored areas where the Plastigauge lifted onto the bearing shell, we're looking at 2.5-3.0 thousandths of an inch. I don't have a spec, but in general, that's a little bit on the loose side of ok.

This makes sense because the crankshaft is a little on the undersized side of ok.

One down, five to go. I'll do a final torque to 0.007 bolt stretch miraculously lining up the castellated nut with the cotter pin hole once I get all of the pistons installed.
Here's a view from the other end. Almost half done.

March 16, 2008

Success! Now all of the rod bolts need to be torqued so that each bolt stretches between 0.005 and 0.007 inches.

This provides maximum holding power yet is still within the elastic limit of the fastener.


This procedure is famously painful in Rolls-Royce circles:

Each connecting rod bolt is measured in its unstetched state. Then each bolt is torqued to 225 in-lbs. and measured again. This will cause the bolt to stretch a few "thou". Hopefully a slot in the castellated nut is not yet lined up with the hole in the bolt.

Next, tighten the nut hopefully less than ~45 degrees so that the hole does line up. Measure the bolt stretch and pray that it is in spec.

Piston (ref)
Left Unstretched
Left Stretched
Right Unstretched
Right Stretched
I was lucky. Although I had to swap the nuts left to right on five out of six cylinders, everything ended up within spec. (The left hand nut on #4 rounds to 0.005 so that counts!)
Here's the bottom end with cotter pins inserted temporarily into the rod nuts until I can give them the Rolls-Royce treatment.


©2008, Sherbourne Mews, LLC
Click here to contact the webmaster.