Rebuilding Westerbeke W30, aka 4-91

[sanibel sailor]

Project has been on hold for a bit. Turns out the MGA big end bearings were not the right size. Took a good bit of shopping to get a set in the right size. Finally came from a tractor supplier in England. $87 shipped is fairly expensive, still dirt cheap compared to Mother Westerbeke. Been doing some other shopping and cleaning in the meanwhile. Hope to start reassembly shortly.

[Spookster999]

I rebuilt my w30 last year. I purchased the vast majority of the parts from Northwoods Tractor, the website is Northwoods Tractor.

They area small family business in Wisconsin, great service and good pricing. Ask for Cynthia.

Good luck with the project
John

[captd44]

[QUOTE=Spookster999;2451857]I rebuilt my w30 last year. I purchased the vast majority of the parts from Northwoods Tractor, the website is Northwoods Tractor.

They area small family business in Wisconsin, great service and good pricing. Ask for Cynthia.

Thanks for the tip, I've been searching for a US source.

[sanibel sailor]

Big end bearing supplier I used was Charnley's in England, another small family business, a bit cheaper than Northwoods. They purchased a major portion of the Leyland tractor stock when they went out of business. Northwoods gets their parts from another UK supplier that does not ship direct to the US.

Got all the pistons installed this evening. Fortunately all the journal clearances were within spec using my plastigauge. Turns over without binding, not exactly easily but it turns. Local auto parts store has a loaner piston ring compressor, although it's only $10 to buy it, I might just keep it. Happy to get all the Pistons in without breaking a ring. I would have been a major setback.

[sanibel sailor]

From below. Notice I was not able to remove the oil pump housing. Machinist said it was no big deal. I did get a new innards for it.

[sanibel sailor]

Up top. Nice to see all the little arrows on the Pistons pointing the right way.

[sanibel sailor]

Camshaft slid in easily this evening. Started to install the front plate when I came across next problem. The distance between the crank and cam is different between the MGA and diesel, meaning my front plate gasket does not fit. I could possibly make a new gasket. More importantly, the timing chain I bought will not fit either. Fortunately, all the parts from Moss Motors are returnable for 6 months. The entire lower gasket set was only $13, so no great tears over that. Probably drop off any unused parts to the local British sports car club guys.

Time for another tractor order...

[sanibel sailor]

I did make and install a block-off plate for the mechanical lift pump. Plan on using an electric model.

[jimbunyard]

Based on your last response to a suggestion I made, I don't expect you to give much credence to another one, but for others that might be following the thread, the standard practice for 'shade tree mechanics' when rebuilding/replacing/refitting a head, without skimming the head/block interface at a machine shop, is to take a good, flat file and dress the block just enough to cut the material pulled up by the torque of the head bolts down closer to flush with the majority of the block/head interface.

The phenomenon is easily seen in this picture




where there is a ring of bright metal around every head bolt hole...

Of course, if the liners protrude above the block surface it's too late anyway, and you'll probably be OK, but cutting the raised material around the head bolt holes closer to the actual plane of the sealing surface will result in a better, longer lasting seal between the head and the block...

[sanibel sailor]

Thanks Jim. Did not know to do that. Wish now the shop had done it or I had done it before I got the holes filled, a bit worried about shavings in the cylinders.

[sanibel sailor]

Better...

[model 10]

How does oil get to the rockers?

[sanibel sailor]

From the MGAguru site:

There is also one vertical hole from the rear camshaft bearing journal where oil can flow upwards to the top of the block. The camshaft rear journal has a front to back oil flow slot in camshaft rear journal groove machined in it. This groove will align with the vertical hole once for each revolution of the camshaft (every second revolution of the crankshaft). This results in a pulsed output of oil from the rear cam bearing to the cylinder head, as the rocker shaft assembly only needs a small amount of oil flow. This pulsed flow metering avoids dumping large flow to the head (which would result in lower oil pressure for the rest of the engine).

Oil rising though the vertical hole goes through the head gasket, through the cylinder head, through the rear rocker shaft pedestal, and into the hollow rocker shaft. From there the oil flows out through radial holes in the rocker shaft to lubricate each of the rocker arm bearings.

In each rocker arm there are two small drill holes. One hole runs latterly through the rocker arm from the rocker bushing to the threaded adjuster screw hole, and is plugged at the outer side of the threaded hole. Oil flows from the bushing, through this drill hole, out around the wasp-waisted girth of the adjuster screw, through a radial hole into the center of the screw, and out a hole in the bottom end of the screw to lubricate the ball and socket joint at the top end of the push rod. Some later model MGB engines (and modern replacement rocker arms) do not have this oil delivery path in the screw end of the rocker arm.

The second hole in the rocker arm comes out at an angle from the top shoulder of the rocker bushing area so that some oil is squirted in the general direction of the tip of the rocker arm. With a little luck (and a bit of splashing around) this lubricates the rubbing end of the rocker arm and the tip of the valve stem, as well as having a bit of oil splash through the valve spring and enter the top of the valve guide to lubricate the valve stem. The oil entering the valve guide will eventually exit from the bottom of the guide into the port above the valve head. With the intake valves, the oil will enter the combustion chamber where it will be mostly burned along with the fuel/air mixture. In the case of very loose valve guides, excessive oil passage here can create smoke in the exhaust, wet the spark plugs, and leave carbon deposits in the combustion chamber when the oil burns of gets baked on to the surfaces. With the exhaust valves, oil from the guides is generally blown out the exhaust port creating soot or wet oil in the tail pipe. Sometimes this oil can be burned in the exhaust stream if it is hot enough, if there is a little oxygen left over in the exhaust (lean mixture at the carbs), and especially if there is a catalytic converter being fed fresh air from an air pump (post 1974 engines).

Oil escaping from the rocker bushings and the drill holes in the rocker arms runs down through the holes in the cylinder head around the push rods where it flows onto the tops of the cam followers (tappets or valve lifters). There it lubricates the ball and socket joint at the bottom of the push rod as well as the tappet and the bore in the block that the tappet rides in. A small amount of oil escapes from the bottom of the tappet bore, while most of the rest returns to the sump via drain holes beside the tappets. As it drains directly on the camshaft it helps to lubricate the cam lobes and tappets and the drive gear for the oil pump and distributor.

Sorry you asked?

I read the whole article to make sure I understood and cleaned all the pathways, as much as reasonably possible.

[model 10]

[QUOTE=sanibel sailor;2460095rutor.
Sorry you asked?
I read the whole article to make sure I understood and cleaned all the pathways, as much as reasonably possible.[/QUOTE]

Good for you, but wtf is with MG? That is a stupid oil system. They had a set of contact points in the fuel pump on their cars too.

[sanibel sailor]

MGA has fundamentally same engine, BMC B series, but gas. Lots more info out there on them than the W30. The oil system seems to work acceptably, although I am certain that it might be able to be improved. Keep in mind it was designed in the early 1950's, and used in various forms in millions of vehicles.

The MGA does not have electrical contacts in the fuel pump. Standard mechanical drive off a dedicated cam lobe identical to the W30. You may be referring to the T series from the 1930's