Wednesday, March 25, 2020

Oil Filter Upgrade

PROJECT 51: Oil Filter. The MG uses a felt cartridge-type oil filter element that is housed inside of a canister that is bolted to the oil pump. They are readily available (from MG parts-suppliers) but cost about twice what an equivalent modern-day spin-on filter does. They are also very messy to change.
Since I will be changing the oil and filter several times during the break-in period when I get the engine running, a bought a kit that converts the original style filter to a spin-on. But with all of the detail I've put into the looks of the engine, the adapter and filter really looked out of place. So, I painted them both the MG canister color, and even added a reproduction vintage Purolator sticker to the filter. Now, it's not QUITE so glaring that it's not original.

Felt filter element cartridge.

Spin-on filter on another MG.

Original MG canister.

"Disguised" spin-on filter.

Sunday, March 22, 2020

Rocker Arm Installation

PROJECT 51: Rocker Arm Assembly Installation. A while ago I posted about rebuilding the rocker arm assembly with new bushings and a new pivot shaft. It has been sitting on the shelf since then, waiting for the engine to be reassembled.
Yesterday I put the new tappets (or lifters) into the block, sitting against the new cam, and then slid the new pushrods through their holes and into the tappets. Lastly, I set the rocker assembly onto the block, and torqued down the bolts. That "lastly" was wishful thinking!
When I backed off the adjusting screws in the rockers to set the .012" valve clearance, I found that they wouldn't retract far enough to even get to "zero" clearance. That meant that all of the valves were being held partially open by the combined height of all of the new and reconditioned parts.
I removed one of the tappets, and measured it against one of the old ones. I found that the new one was .017" taller that the original. That's kind of a wide tolerance for a precision-machined part, but the adjusting screw in the rocker should easily have taken care of that.
I realized that the real problem was that the block and the head had both been machined down (by two different shops) to make them perfectly flat. Neither gave me a report on how much they needed to take off. Then, it occurred to me that Brutus had most likely had the same thing done when he rebuilt the engine. The combination of four machinings dropped the head (and therefore the rockers) down so much that when added to the extra-tall tappets, there was no more adjustment in the screws.
I added shims under the rocker posts, and determined that I needed a minimum of .030" added height to be able t adjust the valve clearance to .012". One option would be to grind the bottom of the tappets to make them shorter, but I am always reluctant to make a change like that, which I can't undo if I don't like the result. Also, it would likely have gone right through the case-hardening on the bottoms of the tappets, leaving them "soft" and subject to wearing out very quickly.
So, I decided to make a set of spacer shims to raise the rocker posts up. I was able to use a piece of 18-gauge steel that I had on hand, which gave me a boost of .048", allowing for a little more adjustability.
The rocker assembly is now torqued in place and the clearance set on all of the valves.

Measuring height of old tappet on the mill.

Shims under rocker post to determine the "boost" required.

Final spacer shims on head.

Final assembly (or is that finally assembled?)

Wednesday, March 18, 2020

Water Pump Rebuild

PROJECT 51: Water pump rebuild. Typically, when rebuilding an engine with lots of miles on it, the water pump is replaced without a second thought. For a Chevy 350, the prices I found range from around $30 to $80. For the MG, a professionally-rebuilt unit (the new ones they make are NOT recommended) is $250, and that is using a cleaned-up original sixty-something-year-old cast iron body.
When I took my pump off the car and cleaned it up, I discovered that it had a bronze body, and after some research, I found out that it was an aftermarket unit made in the 70's, and is highly desirable because the bronze won't corrode the way cast iron does. It also has a six-blade impeller, where the stock unit has only four, and therefore moves more water.
I held onto the improbable hope that I might be able to reuse it, but although the impeller turned freely, there was obvious "cogging" in the bearings, probably caused by corrosion. When I dismantled it, I could see that water had leaked past the seal and collected between the two open-sided bearings, causing rust in one spot in the rear bearing, resulting in that cogging.
The bearings are a common metric size, and I could find several sources for those, but the seal was a different matter. Even if one of the MG part-supply houses had sold a rebuild kit (which they don't) it would be unlikely to fit my aftermarket pump.
I took the old seal assembly out of the pump, but without a manufacturer and part number on it, it took a good deal of online searching and several phone calls to finally locate a company that could supply this type of seal, and then some e-mailed photos to narrow the search to a part number.
Many thanks to Kara Gardner of "Champion Hi-Tech of Oklahoma, Inc." for her diligent help in finding a manufacturer for my seal!
A slight modification to the hub of the impeller was required to use the ceramic mating surface of the new seal, but that will produce a better and longer-lasting seal against coolant leakage.
After polishing the bronze body for show (the original would have been painted MG-red) the new bearings and seal components were assembled, and the unit is ready to be attached to the engine.
Total cost to rebuild: $52.

Water pump still attached to engine.

Old and new bearing.

Old and new seal,

Seal seen near seal-mating surface of bronze impeller.

Turning the impeller to fit the new ceramic mating surface part.

New ceramic mating surface part in place.

New seal in place.

Rebuilt water pump ready for installation.

Tuesday, March 17, 2020

Still Searching ...

PROJECT 51: Still searching. In 1982 Tom Peters and Robert H. Waterman, Jr. published a book titled "In Search of Excellence." In the many years that I ran my own companies and dealt with myriad suppliers and vendors, I was always tempted to set my sights lower, and write a more realistically-titled work called, "In Search of Competence."
Brutus has given me enough to fill a volume all by himself, but he's not alone. When I sent my crankshaft out to be reground .010" undersize by an engine machine shop that I had used before and had been happy with, they were forced to send it outside, because their grinder-operator had passed away recently, and no one else was trained on the machine. When they got it back, they checked it, and found that it had been ground below the lowest acceptable tolerance. So, it went back out to be ground down to .020" undersize. (This was over the course of more than two months!)
After I assembled the engine with the reconditioned connecting rods I noticed that it took far more effort to turn the crankshaft than I thought it should have. After much analysis I eventually determined that the rod journals on the crank were not flat! The grinder operator had apparently chosen a narrow grinding wheel, and then not re-dressed its surface for his final few passes, so the edges were rounded, and the journals were .001" or more larger at the edges than in the middle. That is just enough to make the bearings bind, metal-to-metal, against the journals when there should be a tiny gap filled with oil. The shiny areas in the photo of the bearing show where it was binding.
So, I had to take the engine apart, yet again, and have the connecting rod journals of the crankshaft reground to .030" undersize. This time, however, by the shop that specializes in MGs. While still at the shop, we checked the fit of the new bearings with "PlastiGauge" material. This is a thin, precisely-made piece of plastic that looks like fishing line. A short piece is set on the journal, and the connecting rod is torqued down on top of it. This squashes the plastic to a very precise width, depending on how much clearance there is between the bearing and the journal. The bearing cap is then removed, and the width of the squashed gauge is measured against a gauge strip. All four journals showed .0015" clearance; right on spec.
When we encounter the kind of incompetence that necessitated a second and a third regrind on the crank, my wife and just look at each other, and say, "Still searching …"

Shiny bands at top and bottom of the bearing are where
it was making metal-to-metal contact.

Crank being held in polisher, for inspection.

What looks like a blemish across the middle of the
journal is the squashed PlastiGauge.

The paper packet that the PlastiGuage comes in is used to
measure the gauge after squashing.