Alec's Automotive Machine Shop
This year's technical tour was another complete success. Thanks to Mike Handfield for organizing the event. About 25 members were hosted by brothers Don and Doug Borden at Alec's Automotive, 3891 Fraser Street, Vancouver. The shop is really old and really interesting. You half expect the equipment to be run by belts from the ceiling, instead it is packed with excellent machine tools. There isn't a sharp comer anywhere, as all the rough edges have been worn smooth by years of use.
The shop was purchased by Don and Doug's father as a gas station in 1948. Don explained why the shop is located in a relatively residential area. Apparently it started life as a blacksmith shop at the time when Fraser Street was the main commercial route from Vancouver to Richmond, and much of the haulage was horse drawn. The corduroy wood roads over the boggy areas south of Marine drive would pull the shoes off the dray horses and they would start to go lame at about Fraser and 23rd Ave. so an enterprising blacksmith opened a shop at that location.
According to Doug this is the first time they have been asked to host a technical night in all their years of operation. They certainly went out of their way to make it interesting. They had two of their machinists Rob and Jim on hand and all four of them demonstrated the equipment. They work on a wide variety of engines and will do anything from basic cleaning and machining to complete engine overhauls including reassembly. They do lots of domestic engines but that night they also had heads off of both a Mercedes 4 and a Volkswagen V-6. The latter is a bit more of a not-quite-inline 6 as it uses a single cylinder head. I recall that Lancia produced a four many years ago based on the same principle. In the antique department they had a flat-head V-8 Ford block and an in-line four from a Model "A". The "A" engine made use of babbitt bearings and a splash lubrication system. The metal bearing material was cast integral with the connecting rods. As the bearings were rather soft they were prone to rapid deterioration. It was common to unbolt the rod caps and remove shims to "tighten" the bearings back up.
Throughout the evening they demonstrated each step in a typical engine rebuild starting with disassembly and caustic cleaning of the parts.
The first machining step in rebuilding cylinder heads is to check and renew the valve guides if necessary. As the guides are used in conjunction with a pilot shaft for all following operations on the head, it is absolutely necessary to eliminate any excessive slop in the guides. These can be sleeved or replaced entirely with new guides. Valve seats commonly fail and need attention. We saw an example of a head used on an engine burning propane. The valve seats on these engines tend to get "pounded out" with wear and frequently need replacing. The old seat area is machined out with a special cutting tool on a milling machine. The cutting tool is guided with a pilot shaft fit into the valve guide. A new seat is then pressed into the freshly machined area. That seat is then cut with a three-angle cutter and then finished with a stone. The valves are then checked for stem wear. Valves faces can be dressed using a machine with a rotating grinding stone. The face of the head is machined to provide a perfectly flat surface to mate to the block.
Cylinder bores wear out over time from the friction of the pistons and rings. Depending on how badly worn, they are either machined out on a boring machine or honed on special machine which uses a multi-stone hone. In extreme cases, cylinder liners may be installed. This involves boring the cylinder out by a considerable amount, leaving a shoulder at the very bottom of the bore. Sleeves are then pressed into the oversized bores and then machined. It is common for the liners to be a better quality metal (these are spun cast) than the block metal itself.
Jim demonstrated the process of adding metal to a crankshaft rod journal. The crank is mounted in a funny offset wobbly drive system that rotates the whole crank on the axis of the rod journal being worked on. Metal is then wire feed welded onto the surface of the journal in a narrow bead, starting at one end and slowly moving across the length of the journal keeping about a 25% overlap between adjacent beads. After the metal has been added, the crankshaft is machined down to the correct size.
Worn camshafts can be freshened up on a camshaft grinder by taking metal off the base circle of a worn lobe to restore the original lift and profile. Often it is better to simply buy a new cam and lifters.
When renewing a clutch assembly, it is wise to have the flywheel resurfaced. They use another special machine, consisting of a slowly rotating turntable (on which the flywheel is mounted) and a high-speed rotary stone. Most flywheels are machined flat across the surface. However, some are machined with a step, designed primarily to complicate the matter and make machining more difficult and expensive.
On their wall, they have samples of engine parts that have had catastrophic failures. For example, there is an oil pan with a wristpin through the bottom, still attached to the connecting rod. Ouch! Crankshafts frequently see bad wear on the front main journal bearing due to (guess what) over tightening accessory drive belts. Remember, you're not driving the whole car through these belts, just the alternator, water pump and fan.
If you are planning an engine rebuild have your machining done at Alecs 604-876-7111.